isasi forum april-june 2008€¦ · 2,000 aircraft accidents and incidents, which made his name...

APRIL–JUNE 2008

In MemoriamPRINCIPLED PROFESSIONALISM

Ronald “Ron” Chippindale(1933-2008)

2 • ISASI Forum April–June 2008

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Volume 41, Number 2Publisher Frank Del Gandio

Editorial Advisor Richard B. StoneEditor Esperison Martinez

Design Editor William A. FordAssociate Editor Susan Fager

Annual Report Editor Ron Schleede

ISASI Forum (ISSN 1088-8128) is pub-lished quarterly by International Society ofAir Safety Investigators. Opinions ex-pressed by authors do not necessarily rep-resent official ISASI position or policy.

Editorial Offices: Park Center, 107 EastHolly Avenue, Suite 11, Sterling, VA 20164-5405. Telephone (703) 430-9668. Fax (703) 430-4970. E-mail address [email protected]; for edi-tor, [email protected]. Internet website:www.isasi.org. ISASI Forum is not responsiblefor unsolicited manuscripts, photographs, orother materials. Unsolicited materials will bereturned only if submitted with a self-ad-dressed, stamped envelope. ISASI Forumreserves the right to reject, delete, summa-rize, or edit for space considerations any sub-mitted article. To facilitate editorial produc-tion processes, American-English spelling ofwords will be used.

Copyright © 2008—International Societyof Air Safety Investigators, all rights re-served. Publication in any form prohibitedwithout permission. ISASI Forum regis-tered U.S. Patent and T.M. Office. Opinionsexpressed by authors do not necessarily rep-resent official ISASI position or policy. Per-mission to reprint is available upon applica-tion to the editorial offices.

Publisher’s Editorial Profile: ISASI Fo-rum is printed in the United States and pub-lished for professional air safety investiga-tors who are members of the InternationalSociety of Air Safety Investigators. Edito-rial content emphasizes accident investiga-tion findings, investigative techniques andexperiences, regulatory issues, industry ac-cident prevention developments, and ISASIand member involvement and information.

Subscriptions: Subscription to members isprovided as a portion of dues. Rate for non-members is US$24 and for libraries andschools US$20. For subscription informa-tion, call (703) 430-9668. Additional or re-placement ISASI Forum issues: membersUS$3, nonmembers US$6.

FEATURES3 Ron Chippindale ‘Flies West’By Frank Del Gandio—This “President’s View” memorial pays tributeto one of ISASI’s staunchest advocates.

6 Identifying CVR Recorded Sounds and VoicesBy Yang Lin, Wu Anshan, and Liu Enxiang—Sound identification and voicerecognition are aimed at offering more clues in the analysis and classification ofspeech and non-speech CVR signals.

11 Reverse Engineering Overcomes Corporate AmnesiaBy Peter Coombs—A process of “corporate amnesia” has become commonamong manufacturers, brought about by lengthening aircraft service lives andshortening career spans of design/development engineers within one employer.

15 Critical Aspects of International Incident InvestigationsBy Deborah J. Lawrie, Robert N. van Gelder, and Jan Smeitink—The very fineline between incident and accident clearly emphasizes the importance of havingwell-trained airline investigators.

20 Flight Data—What Every Investigator Should KnowBy Michael R. Poole and Simon Lie—The correct interpretation of flight data and/oraudio data requires a full understanding of the entire signal path from measurementto recorder to investigator.

DEPARTMENTS2 Contents3 President’s View

24 ISASI RoundUp30 ISASI Information32 Who’s Who—A brief corporate member

profile of WestJet

ABOUT THE COVERIn Memoriam: Principled Professionalism—Ronald “Ron” Chippindale (1933-2008)

CONTENTS

April–June 2008 ISASI Forum • 3

Ron Chippindale ‘Flies West’By Frank Del Gandio, ISASI President

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PRESIDENT’S VIEW

Ron gained international attention andrespect in 1979 as the investigator-

in-charge of the investigation into the tragicAir New Zealand DC-10 accident in which257 persons died when the aircraft descendedinto an ice field near Mt. Erebus in Antarctica.His work on the case has been described asnothing short of brilliant.

“To fly west, my friend, is a flight we all musttake for a final check.”—Author unknown

On February 12 at 7:25 a.m., one of ISASI’sstaunchest advocates began his “flight west.”Ronald “Ron” Chippindale was doing his dailyearly morning walk along a footpath near his

home in the Aotea subdivision of Porirua, Wellington, NewZealand, when an 18-year-old driver lost control of his car andstruck Ron. He died instantaneously.

Ron joined our Society in 1971 and his involvement in ISASIwas nothing short of phenomenal. He was instrumental informing the New Zealand Society and became its first president,serving in that post until 2004. He was the NZSASI councillorup to his death. Ron attended every scheduled InternationalCouncil meeting and was very involved and instrumental in theCouncil’s policy-setting role. He met his representation responsi-bilities with zealous constructive participation in debating issuesand ensuring alternative options were considered. Ron chairedthe Organizing Committee for the 1986 ISASI seminar that wassuccessfully held in Rotorua, New Zealand, and again inAuckland in 1996. In 1993, he became one of the first to attainISASI Fellow status. In 2002, he was granted “Life” member-ship. In 2004, he was presented with ISASI’s highest honor, the

Ron flew Bristol freighters with the No. 41 Squadron andlater Hastings and DC-6 aircraft with the No. 40 Squadron. Hehad operations service during the Malayan Emergency and inBorneo.

He has served in a flight safety officer capacity since 1959,and in 1969 Squadron Leader Chippindale became the NewZealand Defense Headquarters flight safety officer responsiblefor the air staff policy on flight safety and the investigations ofaccidents for the Army, Navy, and Air Force. When he retiredfrom the Air Force in 1974, after 24 years of service, he literallymoved next door to be an inspector of air accidents with theOffice of Air Accidents Investigations, a part of the Ministry ofTransport. He became its chief inspector in 1976.

In 1990, the Transport Accident Investigation Commission(TAIC) replaced the Office of Air Accidents Investigations. Ronwas the acting chief executive for 2 years as well as the chiefinvestigator of accidents. As the mandate of the Commissionexpanded to include marine and rail, Ron adopted aviationinvestigation methodologies for those modes.

Ron led or was involved in the investigations of more than2,000 aircraft accidents and incidents, which made his name

(Peter Williams, president of NZSASI, and Steven Lundcontributed to this memorial.)

Jerome F. Lederer Award, for his outstanding lifetime contribu-tion in the field of aircraft investigation and prevention, which isoutlined below.

Ron’s acceptance speech exemplified the characteristics of hisdemeanor and accident investigative manner: short on banter andlong on meaningfulness. He said, “I have been in awe of those whohave been nominated for the coveted Jerry Lederer Award. Tohave myself selected for this honor is rather overwhelming.” (SeeISASI Forum October–December 2004, page 14).

Ron accepts the ISASI 2004 Jerome F. Lederer Award fromFrank Del Gandio, ISASI president.

Ron, born in England on March 26, 1933, enlisted in the RoyalNew Zealand Air Force (RNZAF) in 1950 and was one of thefirst two RNZAF trainees selected to train with the Royal AirForce at Cranwell in the U.K. When he returned to NewZealand, he brought back his bride, June.


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PRESIDENT’S VIEWContinued . . .

synonymous with aircraft accident investigation. He gainedinternational attention and respect in 1979 as the investigator-in-charge of the investigation into the tragic Air New Zealand DC-10 accident in which 257 persons died when the aircraft de-scended into an ice field near Mt. Erebus in Antarctica. His workon the case has been described as nothing short of brilliant.Many compare the complexity of the investigation to that of thelater TWA Flight 800 investigation. With a very small team, hemanaged an investigation in a very difficult environment, andencountered both political and cultural stresses. His mainfinding was challenged through a one-man Royal Commission ofInquiry, but the report of the New Zealand Office of Air Acci-dents Investigations stands as the official report of the accident.Throughout the ensuing controversy about the report’s findings,Ron steadfastly expressed himself and stood by his principles onbehalf of air safety.

Ron was known by his fellow investigators as being a verydedicated, thorough, and impartial professional—one who didnot hesitate to assuredly speak his mind, even in the face ofstaunch opposition.

Recognizing Ron’s skills, ICAO developed a long-standingrelationship with him. In 1986, he worked with the ICAOTechnical Cooperation Bureau, assisting in the South Africaninvestigation where a Mozambique Tu-134 aircraft crashed andthe president was killed. In 1993, when the Russian Federationfinally made available the fight recorders from the shoot down of

At press time, three groups within ISASI have honoredthe memory of Ron Chippindale with donations to theISASI Rudolph Kapustin Memorial Scholarship Fund inRon’s name. The Fund sponsors the annual scholarshipsawarded to college students. The sentiments of thecontributors are well expressed in this comment from thePacific Northwest Regional Chapter: “All of us who knewRon Chippendale—and there are many of us—weredeeply saddened by his unexpected and untimely death.We mourn along with Ron’s wife June, his family, and hismany, many friends.”

Units making donations include the Pacific NorthwestRegional Chapter—$500, the Canadian Society of Interna-tional Safety Investigators—$500, the European Society ofInternational Safety Investigators—$500, and the Mid-At-lantic Regional Chapter—$500. At press time, the NewZealand and Australian Societies were determining the na-ture of their memorial. ◆

Peers Honor Memory

KAL Flight 007, a B-747, over the Sakhalin Islands, ICAOassigned him to the team in the reopened investigation. Ron hasalso been an enthusiastic supporter of the ICAO AIG meetings.

Ron (second from right) makes his New Zealand councillor’s report to the ISASI International Council at its September 2004 meeting.

Ron’s presence will be sorely missed by his family,


In 1999, he was an ICAO consultant assisting the secretariat inthe conduct of that year’s meetings. He served several times as aconsultant assisting in various projects, including the develop-ment of the ICAO circular on family assistance and enhance-ment to the ICAO ADREP data system.

Ron was a member of the Returned and Services Associationfor military veterans and a Fellow of the Royal AeronauticalSociety. He was also the recipient of the New Zealand 1990Commemorative Medal for his services as chief inspector of airaccidents and in 2007 received the New Zealand Special Service(Erebus) Medal, awarded to those involved in the Erebusaccident recovery and investigation.

Among the 280 people saying a final farewell at his funeralservice was the New Zealand minister for Transport Safety andrepresentatives from the Air Force, the aviation industry, andpublic service. Ron’s family members gave moving accounts of aloving father and grandfather. Capt. Tim Burfoot, chief investi-gator of the Transport Accident Investigation Commission, gavean overview of Ron’s accident investigation career. That wasfollowed by eulogies from Paul Mayes, on behalf of ISASI andASASI, Peter Williams on behalf on NZSASI, and a personaltribute from Milton Wylie, a friend and co-worker of many years.Ron is survived by his wife June, four children, 10 grandchil-dren, and one great granddaughter. His presence will be sorelymissed by his family, friends, ISASI, and the aviation community.

As the last post and reveille were sounded, a formation ofthree Royal New Zealand Air Force aircraft made a fly past withtrailing smoke.

A fitting send off to his “flight west.” ◆

Ron in a 1992 photo at his TAIC chief’s desk.

Following the presentation of the New Zealand Service Medalfrom Police Minister Annette King (center), Ron acceptscongratulations from Police Commissioner Howard Broad. TheMedal was presented for his IIC leadership of the accidentinvestigation into the DC-10 that descended into an ice fieldnear Mt. Erebus in Antarctica in 1979.

Ron (second from right) is among the five ISASI Fellows presentat ISASI 2005. Shown, left to right, are Ron Schleede (2002),Caj Frostell (2003), John Rawson (2005), Ron (2004), and JohnPurvis (2001).

friends, ISASI, and the aviation community.○

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(This article was adapted, with permission,from the authors’ presentation entitled SoundIdentification and Speaker Recognition forAircraft Cockpit Voice Recorder, presented atthe ISASI 2007 seminar held in Singapore,Aug. 27-30, 2007, which carried the theme “In-ternational Cooperation: From InvestigationSite to ICAO.” The full presentation includ-ing cited references index is on the ISASIwebsite at www.isasi.org.—Editor)

Traditionally the flight data recorder(FDR) has played the major role inestablishing the causes of most acci-

dents or incidents. However, informationcontained in the cockpit voice recorder(CVR) is also very useful during such in-vestigations by providing a better under-standing of the real situation. The CVR can

act effectively as a latent signal transducerfor both speech and non-speech audio in-formation. Some typical techniques, such assound identification and voice recognition,appear to offer significant clues in the analy-sis and classification of speech and non-speech CVR signals.

The CVR records audio information onfour channels. Non-speech informationfrom the cockpit area microphone (CAM)is recorded on Channel 1. CAM recordsthumps, clicks, and other sounds occurringin the cockpit other than speech. Channel 2and 3 of the CVR record speech audio in-formation from the captain’s and firstofficer’s audio selector panels. Channel 4records the audio information from thejumpseat/observer’s radio panel.

Background cockpit soundidentificationWhile it may be hard to believe that non-speech sounds are highly important to theinvestigation of aircraft damage, they arebecause the background cockpit sounds canreveal problem areas of the aircraft duringthe time leading up to the accident. Non-speech data from the CAM can be analyzedwith sound spectrum analysis to detectwhirl flutter, as well as possibly distinguishthe sound of a bomb explosion from thesound of cabin decompression. Spectrumanalysis can also be used to confirm thatthe clicks and thumps recorded by the CAM

are simply generated by cockpit controlsand the sound of the aircraft movingthrough the air.

Analysis background information re-corded in aircraft CVRs has been proposedas a complement to the analysis of onboardFDRs in civil aircraft investigations. Onereported case provides a good example ofthe analysis of CVR data playing a key partin an aircraft accident investigation. In 1992,a 19-seater commuter aircraft crashed dur-ing an evening training mission. At thattime, the U.S. Federal Aviation Agency(FAA) did not require the installation of anFDR on board all small commercial air-crafts, and the CVR on board the small jetthat crashed was the only flight record avail-able to provide clues to the causes of theaccident.

Fortunately, in this case, the CVR record-ing not only included the voice communica-tion, but also structural acoustics as well asother sounds and noise sources. This al-lowed the accident investigation to focus onthe non-speech sounds taken from the CVRtape. A close inspection of the time seriesfrom the CVR track revealed a periodic setof transient components occurring at a fre-quency of 0.86 Hz. Comparing this fre-quency with an independent dynamic analy-sis of the engine mount damage, the 0.86Hz transient data were demonstrated byindependent structural and flutter analy-ses to be quite close to the frequency expe-

Yang Lin has more than12 years’ experience inthe field of aviation safetyand is an ISASI member.Currently she is an airsafety investigator (ASI)and senior engineer at

the Civil Aviation Safety TechnicalCenter (CASTC) of Civil Aviation ofChina (CAAC), where she has beenworking since 1994. While at CASTC, sheanalyzes and presents recorded data insupport of accident/incident investiga-tions and also conducts flight data

recorder readouts on behalf of govern-ment authorities and airlines in Chinaand other countries.

Wu Anshan is a seniorASI with CAAC, havingjoined the agency in1970. He investigates theair traffic control andorganizational aspectsof aviation accidents

and incidents and has substantiallycontributed to more than 20 significantinvestigations.

Liu Enxiang is thedeputy director at theCAAC’s Office of AviationSafety. An 18-year veteranof CAAC, he has partici-pated in several nationalaircraft accident investi-

gations as an investigator-in-charge (IIC)and as an expert in investigation of avion-ics equipment. He graduated from Nan-jing University of Aeronautics and Astro-nautics with a degree in aeronauticalengineering and has commercial aviationaircraft maintenance experience.

Identifying CVR Recorded Sounds Sound identification andvoice recognition are aimedat offering more clues inthe analysis and classificationof speech and non-speechCVR signals.By Yang Lin (AO5012), Center ofAviation Safety Technology (CAST)of CAAC, and Wu Anshan andLiu Enxiang, General Administra-tion of Civil Aviation of China(CAAC), Air Safety Office

Photounavailable

Photounavailable


rienced from a damaged engine mount.Moreover, there was a sudden, loud

sound at the end of the tape. This 25-milli-second-long event was much louder than thesound in the cabin. Although this shortlength of the sound did not provide adequateaudio listening time, there was enough sig-nal time and amplitude to perform waveletand voice recognition analysis. The conclu-sion drawn after the investigation was thatthe engine on the starboard wing separatedduring the flight. Subsequently, the fallenengine struck the tail of the aircraft, dam-aging most of the horizontal surfaces. Theloss of the engine also led to the separationof the right wing panel outboard of the en-gine. As a result, the aircraft pitched down,rolled to the right, and crashed.

The results of the accident investigationdescribed above, and that of Pan Am Flight103, which disintegrated over Lockerbie,Scotland, in 1989 due to a bomb explosion,motivated CASTC to explore the analysisof aircraft CVR sound sources for use inaircraft accident investigations.

In our system, background cockpitsound identification is used to find the au-dios identical to the given audio in the back-ground cockpit sound database. An audioID is identified by audio fingerprint inacoustics. An audio fingerprint is com-posed of a series of audio features. Gener-ally, audio feature design should obey thefollowing guidelines, as noted in J. Haitsmaand T. Kalker’s “Robust Audio Hashing forContent Identification”:• Discriminability: sensitive enough to dis-tinguish the different audios.• Robustness: stable enough to variouscodes, channels, and modest noise.• Compactness: small enough for easystorage.• Simplicity: inexpensive to compute andeasy to implement.

There are many approaches available toextract audio features. Mel FrequencyCepstral Coefficients (MFCC) are used asaudio features in “Robust Sound Modelingfor Song Detection in Broadcast Audio,” and

of indexes of bands with significant energy.In the approaches cited above, the audio sig-nal is segmented into frames first and a setof features are extracted frame by frame.Some approaches compute a block of fea-tures from a big segment of audio.

The background cockpit sound featureextraction approach proposed in this articleis based on “Robust Audio Hashing for Con-tent Identification.” It takes into accountthat the sign of spectral band energy dif-ference (both in time and frequency axis) isvery robust to many kinds of processing.By analyzing this approach carefully, wepropose an improved approach, one thatenhances the robustness of the audio fea-ture significantly. When audio features areready, the below outlined Background Cock-pit Sound Identification System (BCSIS)will be able to search identical audios in thedatabase quickly and effectively.

J. Haitsma presented a method that lo-cates the potential identical audios by a hashtable. It is quite efficient. But it needs aboutfour times or more space to save data com-pared to other methods, and it slows down

dios with similar distribution will continueto go in for the next fine match. Since thedistribution comparison is processed by ablock of frames instead of frame by frame,it can search audios quickly. The beam-based search approach cuts off brancheswhose cumulative match scores are higherthan the beam width from the best score.Plenty of unpromising paths are prunedaway during the search process. The searchspace is reduced dramatically and high ef-ficiency is achieved.

Framework of BackgroundCockpit Sound IdentificationSystemFigure 1 shows the framework of the Sys-tem. It is composed of three modules: fea-ture extraction, audio search, and audiodatabase. When audio signals are fed intothe System, it extracts audio features first.Audio features are compared to the featuresin the audio database. Audio candidates aregenerated according to the result of thematch process.

The feature extraction module does

and Voices

Figure 1. Framework ofBackground Cockpit SoundIdentification System.

in “Method and Article of Manufacture forContent-Based Analysis, Storage, Re-trieval, and Segmentation of Audio Infor-mation.” “Content-Based Identification ofAudio Material Using mpeg-7 Low-LevelDescription” takes the spectral flatnessmeasure as feature parameters. C.Papaodysseus takes the choice of band rep-resentative vectors, which is an ordered list

the process dramatically when audios arein bad quality.

A. Kimura adopted a two-pass searchstrategy. He generated the vector codebookof audio features first and obtained the dis-tribution of vector code within a period ofaudio. This distribution is then comparedto that of a given audio. This comparison isregarded as the first rough search. The au-


some preliminary processing, such as downsampling and low band pass filtering. Thenit computes the audio features using thealgorithm described below. The audio fea-ture database stores the audio featurescomputed in advance. The audio searchmodule compares the features of possibleidentical audios and outputs the best can-didates.

Audio feature extraction approach —Fig-ure 2 shows the audio feature extraction flowchart adopted. Because human hearing ismost sensitive to the frequencies below 2,000Hz, high-frequencyparts lose heavilywhen audios areencoded at verylow bit rates. Ac-cordingly, in thisSystem audio sig-nals are downsampled to 5,000Hz first. Then sig-nals are segmentedinto frames andweighted by a ham-ming window. Fou-rier transforma-tion is performed,and spectrum pow-er is obtained. Atotal of 33 over-lapped frequencybands are used atan equal logarithminterval. A 32-bitaudio feature iscomputed for eachframe.

In order to make the audio feature stable,a frame length as long as 410 millisecondsis chosen. Frame shift is only 12.8 millisec-onds. As a result, the frame boundaries ofaudio queries in the worst case are 6.4 mil-liseconds off from the boundaries used inthe database that are precomputed.

Audio search approach—In the audio fea-ture similarity measurement, each frame hasone 32-bit audio feature. The similarity of twofeatures is measured by the Hanning dis-tance, which is the number of different bits.The smaller the Hanning distance, the moresimilar the two features are and vice versa.Bit error rate (BER) defines the similarityof two audio feature serials with the samelength. Let X, Y are two audio feature seri-als, X={x1, x2,…, xN}, Y={y1, y2,…, yN}.Where N is the frame number of the fea-tures. The BER between X and Y is

Where, H(.) is the Hanning distance be-tween X and Y. Obviously, ≤BERd≤, thelower the BER is, the more similar the twofeature serials are.

Beam-based search approach—Whensearching audio candidates in the audio data-base, it would result in very low efficiency if awhole match comparison is processed at ev-ery possible starting frame. A beam-basedsearch strategy is presented in this Systemto avoid low efficiency. The main idea of thisapproach is that it takes the current best scoreas the base and prunes away all branches

whose scores are higher than the base plusthe empirical threshold (beam width).

Automatic speaker recognitionAutomatic speaker recognition automati-cally extracts information transmitted in thespeech signal, which can be classified intoidentification and verification, and identifiesa speaker based on his or her voice in theCVR recording. Speaker identification isthe process of determining which registeredspeaker provides a given utterance.Speaker verification is the process of accept-ing or rejecting the identity claim of aspeaker. Speaker recognition methods canalso be divided into text-dependent andtext-independent methods. The former re-quires the speaker to say key words or sen-tences having the same text for both train-ing and recognition trials, whereas the lat-ter does not rely on a specific text beingspoken (Figure 3).

Current state-of-the-art systems for text-independent speaker recognition use fea-tures extracted from very short time seg-ments of speech and model spectral infor-mation using Gaussian Mixture Models(GMM). Using a Universal BackgroundModel (UBM)/GMM-based system is nowcompulsory to obtain good performance inevaluation campaigns such as the U.S. Na-tional Institute of Standards & Technology(NIST) Speaker Recognition Evaluation(SRE).

NIST has conducted an annual evalua-tion of speaker verification technologysince 1995. Such an approach, while suc-cessful in matched acoustic conditions, suf-fers significant performance degradationin the presence of ambient noise. Some

Figure 2. Featureextraction flow chart.

Figure 3. Speaker Identification and Speaker Verification System.


methods are proposed to compensate forchannel variation and intra-speaker varia-tion by normalization techniques such asthe Cepstral Mean Subtraction (CMS),feature warping, feature mapping, andjoint factor analysis.

Modeling of spectral information by

on longer-range stylistic features providesignificant complementary information tothe conventional system. Another impor-tant issue in the statistical approaches tospeaker recognition is that of score normal-ization, which covers aspects such as thescaling of likelihood scores.

environment is restrained by robust tech-niques. During the speaker modeling pro-cess, input front-end features characterizethe speaker. The GMM or SVM modelingapproach is used to train the target speakermodels, which compose the speaker modeldatabase.

Speaker feature extractionapproachThe speech signal is smoothed in short time.For analyzing the speech signal, the usualframe concept is introduced by shorteningthe speech segment by 10 ms-30 ms. Theshift length is the half length of one frame.To compensate for the attenuation of thehigh frequency, every frame of the speechsignal uses pre-weighted processing.

There are two main aspects of speakerfeatures. First, the physiologic structure isdifferent for each individual, such as the tracklength and oral cavity structure, so the short-time spectral is different. Second, the utteredhabits are different, such as an accent. It canbe described as prosody features. In the fieldof speech signal processing, the former is

Figure 7. Framework of Automatic Speaker Recognition System.

Figure 4. Framework ofAutomatic Speaker RecognitionSystem.

GMM can be improved or complementedby the use of other modeling techniques likeSupport Vector Machines (SVMs) or bytransformations of the cepstral space. How-ever, short-term cepstral modeling fails tocapture longer-range stylistic aspects of aperson’s speaking behavior, such as lexical,rhythmic, and intonational patterns. Re-cently, it has been shown that systems based

Framework of Automatic SpeakerRecognition SystemFigure 4 shows the framework of the Sys-tem. It is composed of three modules: fea-ture extraction, speaker modeling, andspeaker recognition. When audio signals arefed into the System, the speaker featuresare drawn from the input speech segments.Furthermore, the influence of channel and

There are two main aspects of speaker features.First, the physiologic structure is different foreach individual, such as the track length and oralcavity structure, so the short-time spectral isdifferent. Second, the uttered habits are different,such as an accent.


embodied on the structure of frequency. Theclassical features include cepstral and pitch.And the latter is embodied on the variabilityof the speech based on the spectral struc-ture. The classical features include the deltacepstral and delta pitch.

In speaker recognition, the cepstral isused mostly and could achieve a good per-formance. Besides, it can be extracted moreeasily than other features. At present, theMel Frequency Cepstral Coefficients areused successfully in speaker recognition,which is proven in applications. In featureextractors of speaker systems, all of the fea-ture vectors are processed by CMS and thefeature warping method.

Using the delta cepstral informationbased on a time domain proves that the per-formance of speaker recognition is mostlyenhanced. In our system, speech data areparameterized every 25 ms with 15 ms over-lap between contiguous frames. For eachframe, a feature vector with 52 dimensionsis calculated: 13 Mel Frequency PerceptualLinear Predictive (MFPLP) coefficients, 13delta cepstral, 13 double delta cepstral, and13 triple cepstral.

Two of the speaker modelsCepstral GMM system—The GMM sys-tem uses a 100-3800 Hz bandwidth front endconsisting of 24 MEL filters to compute 13cepstral coefficients (C1-C13) with cepstralmean subtraction, and their delta, doubledelta, and triple-delta coefficients, produc-ing a 52-dimensional feature vector. Thefeature vectors are modeled by a 2,048-com-

Figure 5. Flow of speaker recognition.

ponent GMM. The background GMM istrained using data from the NIST 1999 and2001 speaker recognition evaluation. Thefeatures are mean and variance normalizedover the utterance. For channel normaliza-tion, the feature mapping is applied usinggender- and handset-dependent modelsthat are adapted from the backgroundmodel. Target GMMs are adapted from thebackground GMM using a Maximum a Pos-teriori (MAP) algorithm adaptation of themeans of the Gaussian components. Theresulting scores are T-normed.Cepstral SVM system—The CepstralSVM system is based on the cepstral se-quence kernel proposed by “The Contribu-tion of Cepstral and Stylistic Features toSRI’s 2005 NIST Speaker RecognitionEvaluation System.” All of them use basicfeatures, which are similar to the cepstralGMM system. The only difference is thatMFCC features are appended with onlydelta and double delta features. This resultsin a 39-dimensional feature vector. This vec-tor undergoes feature-transformation andmean-variance normalization using thesame procedure as explained in the cepstralGMM system. Each normalized featurevector (39 dim) is concatenated with its sec-ond (39x39) and third (39x39x39) order poly-nomial coefficients. Mean and standard de-viation of this vector are computed over theconversation side.

Speaker recognition approachesAs mentioned above, the speaker recogni-tion includes speaker verification and

speaker identification. The speaker verifi-cation is determined by whether the testspeech segment is uttered from the giventarget speaker or not.

The result of recognition is “YES” or“NO,” and the comparison happens betweenone segment and one fixed speaker. Thespeaker identification is that given the testspeech segment.

The system needs to choose the truespeaker from the speaker models database.The key function is calculating the log like-lihood of the input test speech features andone target speaker model. Its calculatedmethod is denoted as follows:

Where ( )S X is the final output score,( )| hypp X λ is the probability of the

speech segment based on the hypothesismodel; ( )| UBMp X λ is the probabilityof the speech segment based on UBM.The final output score ( )S X is accord-ing as the final answer “YES” or “NO”by comparing with the system threshold.The flow of speaker recognition is shownin Figure 5.

The CVR can act effectively as a latentsignal transducer for both speech and non-speech audio information. Sound identifica-tion and voice recognition are aimed at of-fering more clues in the analysis and classi-fication of speech and non-speech CVRsignals.

From the test we have done, the resultshows that two system works quite well forsome cases, and the search speed is reason-ably fast. ◆

( ) ( ) ( )log | log |hyp UBMS X p X p Xλ λ= −


(This article was adapted, withpermission, from the author’spresentation entitled Use of Re-verse Engineering Techniquesto Generate Data for Investiga-tions, presented at the ISASI2007 seminar held in Singa-pore, Aug. 27-30, 2007, whichcarried the theme “Interna-tional Cooperation: From In-vestigation Site to ICAO.” Thefull presentation includingcited references index is on theISASI website at www.isasi.org.—Editor)

Accident investigation has traditionallyrelied on a variety of sources of evi-dence. One of the most important has

been analytical data supplied by type cer-tificate (TC) holders or original equipmentmanufacturers (OEMs). Such informationis particularly important in those complexinvestigations involving structural failure.A number of problems with these sourcesof data have, however, been encountered inrecent years.

With mature aircraft types, archived de-sign data in the possession of TC holdersmay not be readily accessible. If it is avail-able, it may be in a form not easily identi-fied, understood, or manipulated by theirstructural, aerodynamic, or systems spe-cialists, because they will probably be moreused to operating with state-of-the-art de-sign tools. They are often inexperienced inthe use of earlier methods of technical analy-sis and design data recording systems, rou-tinely utilized in the past in the developmentprocesses of aircraft and their components.This assumes that the relevant data canactually be located and identified, a situa-tion that cannot always be guaranteed.

A process of “corporate amnesia” hasbecome common among manufacturers,brought about by lengthening aircraft ser-vice lives and shortening career spans ofdesign/development engineers within oneemployer. Some manufacturers seek outlong-retired engineering specialists to at-tend meetings with investigators in oftenvain attempts to recapture long-forgottendesign data. Other manufacturers seemreluctant to part with information theyprobably possess, either because they findit technically embarrassing in the contextof the accident or for reasons about whichwe can only speculate. The problem seems

to be at its greatest when theaccident under investigationoccurs far from the home ter-ritory of the type certificateholders.

The above phenomenon canbe unfortunate in circum-stances where the complianceof the subject aircraft with thedesign requirements, or insome respects the adequacyand relevance of those designrequirements to the accident

circumstances, have come into doubt.On a number of recent investigations,

where structural failures have occurred, aprocess of “reverse engineering” has beencarried out by the AAIB, under the super-vision of the author, to combat these diffi-culties. This has been done in order to es-tablish important parameters that mightpreviously have fallen under the provinceof the type certificate holder, but where in-adequate data have come from that source.

Investigation summariesThe two investigations summarized herehave been to aircraft in very different cat-egories, suffering very different accidentcauses. Similarities in the investigative pro-cess for each were, however, considerable.

The first of these events was to a me-dium-sized, offshore, public-transport heli-copter. This suffered a lightning strike re-sulting in damage to a composite tail rotorblade, which ultimately led to failure of thetail rotor gearbox attachment making con-tinued flight impossible.

Although the gearbox fell from the py-lon at the end of the flight, somewhat mi-raculously the hydraulic pipes did not ini-tially fracture. Instead, they continued tosupport the mass of the gearbox for a briefperiod. This preserved the longitudinal bal-

Peter Coombs, anengineering investigatorwith the U.K. Air Acci-dents InvestigationBranch since 1972, hasinvestigated accidents andincidents to most classes

of aircraft including large public trans-port airliners, transport helicopters, mili-tary combat aircraft, and many generalaviation types. Before joining the AAIB,he trained with the British AircraftCorporation. He later served as a designengineer on the Concorde SST. He holds amaster’s degree in aircraft design andpilot’s licenses on single- and multi-engine GA aircraft and on helicopters.

Reverse Engineering OvercomesCorporate Amnesia

A process of “corporate amnesia” has become common among manufacturers,brought about by lengthening aircraft service lives and shortening career spans of design/

development engineers within one employer.

By Peter Coombs, Senior Inspector of Accidents, Air Accidents Investigation Branch (AAIB), U.K.

Figure 1


ance of the aircraft, en-abling a successful au-torotation to take placeinto a rough sea. Shortlyafterward, the pipesfailed and the gearboxfell away and sank to thesea bed. The aircraftdrifted downwind until italso sank. Figure 1shows the aircraft sometime between the loss ofthe gearbox and the finalsinking, shortly after allthe passengers and crewevacuated.

The occupants es-caped by dingy and weresubsequently rescued.Surprisingly, we weresuccessful in recoveringboth airframe and tail ro-tor gearbox from twoseparate locations, bothat depths in excess of 700feet (see Figures 2 and3).

Recordings of the tim-ing and location of thecritical lightning strikewere obtained using meteorological record-ing equipment, as was a time-referenced re-cording of the final radio distress call, madeas the aircraft ditched, following the failureof the normal tail rotor gearbox attachment.

The second accident was a fatal event toa four-seat metal general aviation (GA) air-craft, which suffered the unusual phenom-enon of a failure of the outboard section ofa wing, in a download sense. This occurredwhile flying in smooth air in daylight visualmeteorological conditions. A good qualityradar recording and a reliable meteorologi-cal after-cast enabled the airspeed historyto be calculated with an acceptable degreeof accuracy. It was noted with some concernthat the speed, at the time of the failure,was significantly below the maneuver speedof the aircraft.

Both investigations resulted in develop-ment of methods that could be utilized inwhole or more probably in part during fu-ture investigations, regardless of the sizeof aircraft involved. Both investigations re-quired precise assessment of strength andloadings in localized areas of structure.

The first also required assessment ofloading applied as a result of tail rotor im-balance acting in conjunction with the dy-

namic response characteristics of the tailboom and pylon structure of the rotorcraft.These characteristics significantly raisedthe stress levels in the gearbox attachmentsresulting from rotor imbalance.

The second investigation, to the GA air-craft, took advantage of state-of-the-art tech-niques to establish structural strength andaerodynamic loading figures. These werethought to be more accurate than those avail-able to the original aircraft designers.

The expertise required to carry out thedetailed calculations in support of these in-vestigations was provided by a number ofspecialist analytical companies in the U.K.These have generally grown up during thepast 25 years. In addition, a U.K.-based, in-ternationally known academic establish-ment also supplied such assistance. The lat-ter has a wide range of expertise throughareas of structural design, flight mechan-ics, simulation, and dynamic load analysis.The specialist companies provide expertisein areas ranging from finite element analy-sis to structural dynamics. One has specificexperience on maneuver load analysis offast combat jet aircraft. They act as con-tract engineers to both major aircraftmanufacturers and to other specialist aero-

nautical engineering companies in Europeand North America.

The accidentsThe helicopter, an AS 332, lost part of a com-posite tail rotor blade as a result of a light-ning strike while descending to an offshorerig. Subsequent impact destruction to theremainder of the blade (see Figure 4), asthe rotor struck the tail boom during gear-box separation, disguised the amount of ini-tial lightning damage. It can be seen in Fig-ure 5 that four of the blades have been de-stroyed by this same impact mechanism,although only the one on the left has anyevidence of the earlier lightning damage.

It was required to establish the level anddegree of initial lightning damage on thissingle blade in order to determine the se-verity of the lightning strike that the bladesuffered. This was necessary to establishthe practical validity of the lightning certi-fication requirements to which the aircrafthad been qualified. The loss of the machinehad cast considerable doubt on the ad-equacy of those requirements. It was fearedthat aircraft operating at low levels, in win-ter, in the temperate maritime conditionsover the North Sea, were especially vulner-able. At the time, this was the busiest areaof offshore, long-range, public-transporthelicopter operation in the world.

Figure 3

Figure 2

Tests on a number of ex-service bladeswere carried out at a lightning test facilityto establish the extent of damage inflictedby differing degrees of intensity of lightningstrikes.

It was found, from wreckage examina-tion, that imbalance following the strike hadcreated sufficient vibration to cause one ofthe three gearbox securing bolts to slacken.This both concentrated cyclic bending ononly two attachment lugs and altered thenatural frequency of the tail boom/gearbox

Both investigations resultedin development of methodsthat could be utilized in wholeor more probably in partduring future investigations,regardless of the size ofaircraft involved.


combination. This alteration brought thisstructural frequency (in cycles per second)close to the rotational speed of the unbal-anced rotor with the damaged blade (inrevolutions per second).

A finite element analysis of the gearboxwas carried out using actual measurementsof the casting to create the grid. In Figure 5,you see one of the visualizations of the gear-box showing the varying stress distributionfor a unit loading. The number of cycles tofailure was known, since the times of boththe strike and the final gearbox separationwere known from recordings. The initialevent time was identified precisely using theatmospheric lightning recording equipmentavailable to the U.K. Met Office, while thefailure time was established approximately

from timing of the final VHFcrew distress call. The rotorspeed was known from air-craft data. From these itemsof information, it was possibleto calculate the amount of im-balance that provoked thegearbox fatigue failure andmust, therefore, have beenbrought about by the lightningdamage.

When first calculated, how-ever, without considering thedynamics of the tail boom, themass loss from the blade, tocreate this imbalance, wasfound to be slightly more thanthat resulting from damageclearly caused finally by thecollision between the bladeand the tail boom. See againFigures 4 and 5. This damagehad quite clearly only oc-curred as the gearbox sepa-rated, some minutes after thestrike; something was un-doubtedly wrong with the cal-culated result.

It was, therefore, decidedthat the dynamic characteris-tics of the tail boom/gearboxcombination would be evalu-ated theoretically. This workwas carried out using amanufacturer’s dimensionedlayout drawing of the tailboom and skin thickness mea-surements made on the dam-aged boom by ourselves. Themass of the gearbox was de-termined simply by weighing

the salvaged unit.The new calculated tail boom dynamic

characteristics were confirmed by a reso-nance test of the rear structure of an in-service aircraft while on the ground andwere further corrected theoretically for thepredicted effect of a single, loose tail rotorgearbox attachment. By this means, it wasdetermined that the natural frequency ofthe rear of the aircraft in cycles per secondalmost matched the rotor speed in revs/sec-ond. The cyclic forces applied to the twoeffective tail rotor gearbox attachmentswere thus found, as a result of these closefrequency similarities, to be far greater thanthose initially calculated without taking ac-count of the dynamics of the tail boom.

Only a small mass loss resulting from the

lightning strike was now required to createloading to cause failure in the known time,and a realistic assessment of the pure light-ning damage required to cause this losscould be made. By comparing this calculatedmass loss with the damage inflicted by light-ning tests on used blades, carried out ear-lier using known electrical intensity char-acteristics, it was possible to determine theapproximate magnitude of the lightningstrike. This, although confirming that thecertification requirements then in forcewere realistic in terms of magnitude for thatflight environment, revealed significantdrawbacks in the aircraft’s design process.It showed that the practical effects of boltslackening under vibration loading, to-gether with the similarity of natural fre-quency of the structure to the rotor speed,had not been adequately taken into accountat the design stage.

Certification compliance merely called foran absence of severe structural damage in(static) lightning test conditions. It did notcall for a full assessment of the structuralbehavior of the rotor system and mountingafter the limited lightning damage had oc-curred. No such assessment had apparentlybeen carried out on this aircraft type.

Second accidentIn the case of the GA aircraft, a PA28R-200-2, a finite element (FE) model of the wingbay in which the failure occurred was cre-ated using a manufacturer’s layout draw-ing and measurements of panel thicknessmade on the separated wing and a furthersample wing. Figure 7 shows a visualizationof the model.

An evaluation of control responses wascarried out, using a simple simulator, pro-grammed with a modified NASA computermodel of the aircraft type. This was done toproduce a realistic series of control columndisplacement-time histories of pitch controlinputs, creating a series of wing download-time (negative G) histories as well as otherflight parameters. The span-wise negativelift distribution was calculated and con-verted to engineering units. The time his-tory resulting in the highest negative loadfactors achieved in the simulation series wasthen used to factor the distributed forces.The result was used as the varying aerody-namic force/time input to evaluate the be-havior of the FE model under a varyingdown-load. On carrying out this exercise, itwas found that the theoretical wing strengthfrom the FE analysis was far in excess of

Figure 4

Figure 5

Figure 7

Figure 6


that required to carry the highest loadsimplied by the results of the simulations.

Up to this point, only symmetrical pitchmaneuvers had been considered. It wasrealized, however, that even with thoseforces calculated for such maneuvers act-ing in unison with forces resulting from alarge simultaneous roll control input theload to fail the wing could not reasonablybe approached, much less achieved. Thereason for the wing failure thus remainedentirely obscure.

A review of assumptions made to cre-ate the finite element model was then car-ried out; with a number of more pessimis-tic assumptions applied, the reduction inwing strength was still insignificant.

At this point, further specialist assis-tance was sought. The company that wasconsulted drew attention to the significanceof inertia effects created by rapidly reversedcontrol inputs. It was able to estimate theapproximate mass distribution of the wingstructure and also to create a NASTRAN/PATRAN model of the machine, entirely bymeasurement of a real example and use ofpublished data relating to the type. Thisenabled maneuver loads to be calculated forcontinuously varying pitch and roll displace-ments. It proved possible then to create amaneuver/time history that resulted in fail-ure of the finite element model as a resultof full simultaneous pitch and roll control

Figure 7. Finite element analysisvisualization.

Figure 8

Figure 9. Finite element analysis visualization.

input, followed immediately by completereversal of control inputs in both axes. Un-der these influences, failure loads at thewing station where the actual aircraft struc-ture failed could just be reached at theknown airspeed. The control input-time his-tories are shown graphically in Figure 8.Visualizations of the failure modes areshown in Figures 9.

Calculation of control forces at this speedindicated that these were sufficiently low toenable them to be easily generated by afront-seat occupant. (Control gearing was es-tablished by simply measuring control sur-face angular movement for corresponding

control wheeltravel on an ex-ample of the typeborrowed form e a s u r e m e n tpurposes).

A persuasivescenario to ex-plain the occur-rence, based onthe nature andseating position ofthe aircraft occu-pants, in this dual-control machinewas then devised.

These two in-vestigations dem-onstrate the wayin which capabili-ties from part-ners outside thenormal areas ofexpertise usuallycalled upon by in-vestigators can beharnessed to re-place data moreusually foundfrom OEMs andTC holders whensuch data are notreadily available.Although the ab-sence of manufac-turer’s data mayseem at first agreat handicap,the ever-increas-ing power of mod-ern computersand the rising so-phistication ofc o m m e r c i a l l y

available analytical packages compensatefor much of this loss. These enable data tobe generated and manipulated, which pro-duce results that are no less accurate thanthose achieved in the past by OEMs. Thesewill have used methods that were state-of-the-art at the time of the aircraft’s initialdesign but may be two or more decades oldat the time the accident occurs.

Investigations carried out using suchmethods present a challenge to the manu-facturers that frequently reengage morefully when they see that official investiga-tive bodies are serious about finding the rootcauses of such intricate accidents. ◆


(This article was adapted, with permission,from the authors’ presentation entitled Cri-tical Aspects of International Incident In-vestigations, presented at the ISASI 2007seminar held in Singapore, Aug. 27-30,2007, which carried the theme “Interna-tional Cooperation: From InvestigationSite to ICAO.” The full presentation includ-ing cited references index is on the ISASIwebsite at www.isasi.org.

The authors are founders of the Indepen-dent Safety Investigation & ConsultationServices [ISIS] group, part of whose workis to teach others and, especially airline op-erators, how to investigate serious inci-dents.—Editor)

TTTTT his article is based on a case study ofa serious deicing incident that hadsignificant consequences for ground

handling supervision and developed into abroad-based international investigation,lasting more than 2 years and conducted inaccordance with ICAO Annex 13.

On Feb. 16, 2002, a Fokker 70 aircraft hadbeen parked in Turin, Holland, overnight.Rain and snow fell during the night withlight and variable winds. The temperature/dew point ranged between 2/0°C and 0/-1°C,and enough fuel remained on board for thereturn flight to Amsterdam the next day.

During the pre-flight inspection the nextmorning, ridges of ice 1.5 –2 cm thick werefound under the leading edges of the wings,

and a mixture of slush and ice was found insmall areas on the top of the wings. The air-craft was deiced, and the captain performeda visual check of the wings after the deicing

operation was finished. (Kilfrost ABC 3Type 2/50%).

A short time later, the aircraft taxied fordeparture from Runway 36. A special pro-

Deborah Lawrie isAustralian bornand holds a BSc andbachelor of educationdegree from MelbourneUniversity. She taughtmathematics and physics

and was a flying instructor from 1976until 1979, when she joined Ansett tobecome Australia’s first female airlinepilot. She joined KLM Cityhopper in1993, instructing on the Fokker 50 andlater operating the Fokker 70/100. In 1998Deborah established the company’s FlightSafety Department, and held the positionof safety manager and chief investigatorfor 8 years. She was chairman of theERA Air Safety Working Group from1998-2004. She is currently flying theA330 with KLM.

Robert van Gelder wasborn in the Netherlandsand received his flighttraining at the RoyalDutch Flight Academyin 1973. He graduatedwith a BSc honors from

Loughborough University of Technology

in human factors/ergonomics in 1982and joined KLM Royal Dutch Airlinesin 1978. He currently flies as a Boeing747-400 captain. During the last 17years, Robert has held the positions ofergonomics engineer/human factorsspecialist, line and simulator instructor,chairman of the StandardizationCommittee on the Boeing 737, founderand editor-in-chief of KLM’s flightsafety magazine in for SAFETY, andchief investigator.

Jan Smeitink is amember of the manage-ment team of the DutchSafety Board, whichinvestigates transportaccidents and incidentsand other types of

disasters, serious accidents and inci-dents, as well as crisis managementand disaster control. He joined KLMshortly after graduating as a mechani-cal engineer from the polytechnic collegein Arnhem, the Netherlands. Heflew as a flight engineer on the B-747-200/300 and has more than 10,000flying hours.

Critical Aspects of InternationalIncident Investigations

The very fine line between incident and accident clearly emphasizesthe importance of having well-trained airline investigators.By Deborah J. Lawrie, Robert N. van Gelder, and Jan Smeitink


cedure with a right turn at 500 feet is speci-fied in the case of engine failure during take-off from this runway due to the close prox-imity of high terrain. The takeoff was per-formed using full thrust with the engineanti-ice on. The wind was from the north-east at 3 knots. There were scattered cloudsat 500 feet and light rain. The temperature/dew point was 1/0° C.

All the engine indications were normalduring the takeoff roll. But during the ro-tation the fan vibration in engine No. 1 in-creased, and at liftoff there was a suddenloss of oil pressure and fuel flow to engineNo. 2 and the fan vibration in engine No. 1increased above limits. We now know thatas the wings flexed during the rotation,large pieces of clear ice separated from bothwings causing violent and immediate de-struction of the right engine and damageto several fan blades in the left engine. Thefollowing also occurred:• Accessory gearbox and hydraulic pumphousing were cracked.• Power lever transducer was hanging onits wiring.• Gear box housing was cracked in twoplaces.• Throttle linkage was detached from thefan case.

The situation on the flight deck was com-plicated by the turn that was now neces-sary at 500 feet, a jammed fuel lever on theright engine, which disrupted the engineshutdown procedure, and several other fail-ures that occurred: an autothrottle failure,an autopressurization failure, and eventu-ally a fuel asymmetry warning.

The high-vibration warning on the leftengine was temporarily “hidden” by all theother failures due to the priority allocationof the aircraft’s warning system and insuf-ficient space available to display all thewarnings at the same time on the Multi-Function Display Unit. Due to all the otherfailures, the crew remained unaware of thehigh-vibration problem with the left enginefor the next 10 minutes.

When the high-vibration warning even-

tually surfaced on the Multi-Function Dis-play Unit, the crew then became aware thatthe only remaining engine was not function-ing normally. The first officer later de-scribed the situation as “the aircraft was notflying really well and the engine did not feelsmooth.” The captain declared a MAYDAYand requested vectors to return for an ILSapproach on Runway 36 at Turin. After be-ing airborne for 29 minutes, the aircraft fi-nally landed safely back on Runway 36.

The aftermath[Capt. Lawrie, as chief investigator forKLM, was asked to assist in the incidentinvestigation. She relates her role.—Editor]

By the time I arrived in Turin with thetechnical pilot, investigation of the incidenthad already commenced and was under thecontrol of the investigator-in-charge fromthe ANSV (Italian Aviation Safety Board).

At this stage, it was unclear what hadcaused the damage to both engines. Otherdamage to the fuselage and the surface ofthe right wing led to initial speculation thatthe damage to the left engine may have beencaused by ingestion of debris from the cata-strophic failure of the right engine.

As chief investigator for the airline, I hadsome previous internal incident investiga-tion experience. Quite suddenly now, how-ever, I found myself as the only party onsite, in what was to be an international in-vestigation involving several parties and Iwas dealing directly with the investigator-in-charge. This type of situation is morelikely to develop in the case of a serious in-cident rather than an accident. While theformal procedure calls for an accredited

representative under whose supervision thecompany investigator would act as an advi-sor, the Turin situation called for an ap-proach that deviated from the ICAO An-nex 13 philosophy.

In the Turin situation, a comprehensiveknowledge and understanding of the ICAOinvestigation process as well as knowledgeabout my entitlements and responsibilitiesand those of the other parties involved wasgoing to prove to be invaluable in what wasgoing to develop into a lengthy and contro-versial investigation.

The investigator as advisor roleThe case study also shows that serious inci-dent investigation is just as important asan accident investigation and, therefore,should be performed as comprehensivelyand with the same allocation of resourcesas if it had been an accident. In cases suchas Turin where the operator had been for-tunate to escape disaster, then investigationof this event had the potential to reveal asmuch, if not more, about all the contribut-ing factors that led up to it.

Indeed, it was later revealed that theTurin event had the same “footprint” as theScandinavian Airlines accident that involved

PRECEDING PAGE: This photo illustratesthe icing conditions that existed on theevening of Feb. 16, 2002.ABOVE: Damaged sustained by the Fokker70’s right engine when struck by clearice from the wing.RIGHT: This iced wing is illustrative of theproblem encountered by the Fokker 70involved in the noted incident.


an MD-81 that took off from Stockholm’sArlanda Airport early in the morning ofDec. 27, 1991. Vibrations from the MD-81’sengines were noticed 25 seconds after be-coming airborne. Approximately 1 minutelater, both engines failed. The aircraft wascommitted to a forced landing in a fieldwhere it broke into three parts after theimpact. Remarkably, in this accident therewere no fatalities, and later the investiga-tion revealed that ice from the wings hadentered both engines causing them to fail.

In Turin during the first hours of the in-vestigation, the technical pilot and I workedside by side with the Italian investigator-in-charge (IIC). Our operational knowledge wasvery much appreciated, and we managed toestablish a good relationship with the IIC.Aircraft documents and operating manualswere identified and discussed, a detailed in-spection of the cockpit was made, and a briefinspection of the engines and external con-dition of the aircraft was performed.

The IIC arranged for us to inspect therunway and the surrounding area at thepoint where the aircraft had rotated. Weretrieved pieces of engine acoustic liningamong other broken bits and pieces. It wasat this critical point in time, however, thatthe driver of the airport safety car casuallymentioned that earlier that morning, justafter the incident, he had found some verylarge pieces of ice at the same location. Toclose the day, we were invited to accompany

the IIC to interview the air traffic control-lers who were on duty in the tower at thetime of the incident.

I must emphasize that this event did nothave the high-profile media attention thatone associates with an accident. Also, theseriousness of the event didn’t start to fil-ter through to the interested parties untillate in the day. The company reported thematter to the Dutch investigation author-ity, then known as the RVTV. The followingday, representatives from Fokker and Rolls-Royce arrived in Turin.

The Italian Aviation Safety Board hadinitiated the formal international investiga-tion, but our position as advisor to the Dutchaccredited representative was not formal-ized until after we returned to Holland 2days later. By the time we returned to Hol-land we had• established a good working relationshipwith the IIC.• met several of the other parties whowould be involved in the investigation.• established our value as advisors in termsof knowledge, expertise, and availability.

An accredited investigator from DutchALPA was assigned to me, and together weacted as advisors to the RVTV.

Among the vast quantity of collected datawas information from the digital flight datarecorder, but information from the cockpitvoice recorder was not available due to thejammed fuel lever that had caused the CVR

to keep recording for several hours afterthe incident.

After all the data were collected and ex-tensive analysis of both engines had beenperformed by Rolls-Royce, the process ofelimination led to the conclusion that themost probable cause of the event had beenthe ingestion of large amounts of ice by bothengines. The focus of the investigationturned to the deicing operation, the post de-icing inspection, and the operator’s super-vision of ground handling.

Deicing at European airports was a verycontroversial and high-profile safety con-cern at the time, and a few years earlier theDAQCP (Deicing and Quality Control Pool)had been established. The DAQCP was anorganized group of operators who sharedthe auditing of several deicing contractorsthroughout Europe.

In the Turin investigation, there was con-troversy over• knowledge of and training of the correcttechniques for the removal of clear ice.• ownership of the final responsibility forthe post-deicing inspection.• the operator’s contractual arrangementwith the handling agent that performed thedeicing and the agent that performed theinspection.• the separate arrangement between thehandling agent performing the deicing andthe agent performing the post-deicing in-spection.• the structural safety deficit at an inter-national regulatory level with no certifica-tion rules for ground handling companies.• evidence of previous substandard deic-ing operations in Italy.

In the case of Turin, the company had awritten contract with a deicing agent but onlya verbal contract with the post-deicing in-specting company, which was a separate com-pany to that which performed the deicing.

The crew documentation on board theaircraft indicated that the handling agentwould perform the deicing and the post-deicing inspection, but in this case no post-deicing inspection was performed other


than the visual check per-formed by the captain. Further-more, several findings in rela-tion to training and contractsremained open from the deic-ing pool audit that had beenconducted in January of theprevious year.

Tension between investiga-tors was apparent and under-standable. Pending insuranceclaims and political issues alsoadded pressure to the investiga-tion. The importance of the roleand the entitlements of theDutch accredited representative were abso-lutely vital to the progress of the investiga-tion. In turn, the Dutch accredited represen-tative relied heavily upon the support, knowl-edge, and objectiveness of his advisors.

Several analyses and recommendationmeetings were convened, some of whichwere held in The Hague and some in Rome.The Dutch accredited representative couldnot attend all the meetings in Rome, so onsome occasions we were present at thesemeetings as replacements. We were, there-fore, playing a variety of roles on differentoccasions throughout the investigationranging from a subordinate role to a lead-ership role. We had to balance diplomacywith assertiveness and, above all, we had tokeep our focus on getting to the bottom ofthe true causes of the event.

As this was an international investiga-tion, the importance of a final report in theEnglish language was apparent. Becausewe were more fluent in English, the unioninvestigator and I were given the very im-portant job of writing the report under thesupervision of the IIC. The report and itsrecommendations would not only be impor-tant to our company but also to many otheroperators who had a vested interest in thisvery critical safety issue.

Investigator trainingAs illustrated by the example in Turin,proper training of airline investigators is a

vital facet of the operator’s flight safetyprogram and more importantly the train-ing should be within the reach of, and avail-able to, all operators.

One of the most striking aspects of manyformal accident investigation courses is thatthe bulk of such courses is not relevant tothe airline investigator. Also many coursesare out of the financial reach of smaller op-erators and those who it could be arguedmay need it most.

Fortunately, most airlines tend not tohave accidents. If an airline does have anaccident, the airline investigator will at bestbe an advisor and will certainly never beacting as an investigator-in-charge.

Airlines do, however, have incidents fromtime to time and sometimes these incidentsare serious. Often, though, due to staffshortages or other investigations alreadyin progress, the national investigation au-thorities do not have sufficient time or re-sources to investigate all serious incidentsand at best are sometimes only able to givelimited attention. Even though the investi-gation of serious incidents has been man-dated in the latest version of ICAO Annex13, the reality is that this task more oftenthan not is allocated to the operator itselfand, therefore, the quality of such an inves-tigation depends upon the training of theoperator’s investigators. There is no doubtthat valuable lessons can be learned fromincident investigations, and we are of the

opinion that there is an industrywide un-derestimation of the importance of well-performed incident investigations and qual-ity report writing.

In terms of an airline safety program, itis important that• the seriousness of an event is recognizedand assessed accurately by means of a com-prehensive risk-assessment program.• the airline must be prepared to partici-pate in investigations of serious incidentswith or without the assistance of the stateinvestigation authority.• if the state investigation authority con-ducts an incident investigation, then the air-line investigator should be aware of its re-sponsibilities and entitlements. This pointapplies equally in an accident investigation.

We would argue that investigators shouldbe trained how to recognize a serious inci-dent, how to investigate a serious incident,how to write a report that supports effectiverecommendations, and to develop a sense ofwhen risk should be mitigated. Equally im-portant is the airline investigator’s ability towork with other investigators and the abil-ity to manage a small investigation team. Wemaintain that the proper and comprehensiveinvestigation of incidents is vital to the im-provement of safety.

In the case of Turin, the report also ana-lyzed and produced recommendations inregard to• fueling policy,

Right engine’s damaged fan blades.


• crew hand-over procedures,• preflight inspections,• the Deicing and Quality Control Pool au-diting system,• organization and management of out sta-tion ground handling, and• internal distribution and control of com-pany documentation.

In view of the potential value of well-for-mulated recommendations that arise froma comprehensive investigation, it makessense to give consideration to affordable andappropriate investigator training courses.We also believe that due considerationshould be given to airline investigator poolsor investigator exchange programs.

Our belief is that if investigator pools orexchange programs existed then severalsmaller airlines of limited resources andcapability would benefit enormously fromthe opportunities—not only for their inves-tigators to improve their skills by workingalong side more experienced investigators,but also that all companies would benefitfrom an exchange of ideas and incident in-vestigations could be performed more thor-oughly and proficiently.

Interactive and customizedtraining benefitsIn 2003 the ISIS incident investigationcourse was developed to train investigatorsin order that they may lead and manage anincident investigation and that they may beable to perform the role as advisor in anaccident or incident investigation.

The specific advantages of in-housecourses involved have been• More people were trained and ready toperform investigations, safety assessments,and analysis.• Persons were trained in the same “vein”and were therefore able to think on thesame wavelength.• Persons from several different depart-ments were trained together, which in-creased their individual knowledge and un-derstanding of one another’s roles withinthe company.

• Better capacity and more time to concen-trate on and discuss “regional” issues.• Less costs per head for the company.• Less down time for personnel becausetraveling away from the home base was notrequired.• Increased flexibility for the company incase of production problems.

Why a stand-alone incident investigationcourse and not an integrated accident in-vestigation course?• Airlines have more incidents than acci-dents, and proper investigation of an inci-dent can help to prevent an accident.• Investigation training also requires con-solidation, and working with other experi-enced investigators and advanced trainingis only of value after a suitable consolida-tion period.• Cost, spread of costs, employees are onlyabsent from duties for 1 week at a time in-stead of the usual 2 weeks or more.• Specific learning—more concentrationon the topics and disciplines that are rel-evant to airline operations.• Learning over a longer period of time plusthe opportunity to revise and update previ-ous learning by doing the accident investi-gation training module 6 months to 1 yearafter the incident investigation module.

Why did ISIS set up this course, whilethere are already other courses available?We wanted• to see more emphasis placed on incidentinvestigation.• to see the inclusion of more relevant ma-terial and to give more hands-on practice.• this type of training to be available forall operators, large and small.• investigators to be able to recognize theintrinsic value of other investigation reports.

• to create a course that is portable.We believe that the delivery and teach-

ing methods are just as important as thecontent of the course. Lecturers are trainedin teaching skills in line with recognizeduniversity teacher training methods. TheISIS course is highly interactive, and thenumber of attendees is restricted to smallergroups in order to guarantee individual at-tention and feedback.

We place a very high value on incidentinvestigations, not only from the cost aspectfor smaller companies but also for the addedvalue to safety that will come with compre-hensive, well-performed investigations andassociated quality reports.

It is often the case that many serious in-cidents will have the same “footprint” as anaccident but that a stroke of luck or goodfortune breaks the error chain and an acci-dent is avoided.

This was seen in the case of the Fokker70 icing incident at Turin. Many accidents,on the other hand, would have or could havebeen serious incidents save for one factorsuch as in the case of Cali when the speedbrakes remained extended when the B-757attempted to clear the high terrain. If Calihad been a serious incident and not an acci-dent, then the investigation of this eventwould have been vitally important. The in-teresting thing, however, from our point ofview is that had Cali only been an incident,the investigation may have had to have beenperformed by the airline itself.

We believe that accidents such as the oneat Cali and serious incidents such as the oneat Turin clearly demonstrate the very fineline between incident and accident andclearly emphasize the importance of hav-ing well-trained airline investigators. ◆

We believe that accidents such as the one at Caliand serious incidents such as the one at Turin clearlydemonstrate the very fine line between incident andaccident and clearly emphasize the importance ofhaving well-trained airline investigators.


(This article was adapted, with permission,from the authors’ presentation entitledFlight Data—What Every InvestigatorShould Know, presented at the ISASI 2007seminar held in Singapore, Aug. 27-30,2007, which carried the theme “Interna-tional Cooperation: From InvestigationSite to ICAO.” The full presentation includ-ing cited references index is on the ISASIwebsite at www.isasi.org.—Editor)

Flight data are becoming more readilyaccessible and are increasingly beingused for investigation and airline

safety programs. Modern aircraft record ahuge amount of data compared to just a fewyears ago, but even in the most advancedaircraft recording systems, significantlyless than 1% of the available data are actu-ally recorded. The challenge of analyzingflight data is to recreate an accurate under-standing of an event from that small per-centage of the available data.

The scientific evaluation of data requiresan understanding of the origin, or prov-enance, of the data and how the data wereprocessed. Both authors have seen profes-sional investigators reach mistaken conclu-sions when reviewing recorded flight datawithout fully understanding the origin andhistory.

As parameters proliferate, even the nam-ing of parameters can lead to confusion.

Consider two different parameters that arerecorded on certain B-737 aircraft: SelectedFuel Flow and Selected Heading. In theformer, the “Selected” indicates that mul-tiple fuel flow readings from different sen-sors are available and this particular valuehas been judged to be the most accurateand thus has been selected for display tothe flight crew. In the latter, “Selected”means the target value of heading chosenby the flight crew via the autoflight modecontrol panel. As these two examples dem-onstrate, scientific rigor requires a full un-derstanding of the origin of flight data andhow the data were processed.

It is important that investigators andairline Flight Operations Quality Assur-ance (FOQA) analysts appreciate the prov-enance of the flight data, especially whendrawing substantive conclusions. There isanabundance of flight data analysis toolsthat are becoming progressively more au-tomated, which in turn increases the po-tential to mislead.

ProvenanceThere are many examples where the cor-rect interpretation of an FDR recordingrequires a full understanding of the prov-enance including the methods employed bythe replay ground station. According to theOxford English Dictionary, provenance is“a record of the ultimate derivation and

passage of an item through its various own-ers.” Adapted for the context of recordedflight data, the definition becomes “a recordof a physical measurement or system stateand the changes to that record as it passesthrough various system components untilit is interpreted for an investigation.”

Consider the “Selected Heading” ex-ample above and as shown in Figure 1. Theflight crew uses the heading window on themode control panel (MCP) to choose a flightheading. The MCP transmits this value tothe flight control computer (FCC). TheFCC uses the value for computing the cor-rect flight director and autopilot behavior.

Mike Poole is a principalat Flightscape, a flightsciences companyspecializing in flight dataanalysis software. Hewas with the TSB ofCanada for more than 20

years where he served as the head of theFlight Recorder and PerformanceLaboratory and the Flight RecorderGroup chairman on all major accidents.He also has represented Canada as thenational expert panel member to theInternational Civil AviationOrganization’s Flight Recorder Panel.

Simon Lie is an associatetechnical fellow and airsafety investigator atBoeing CommercialAirplanes. He has anacademic background incomposite structures and

aeroelasticity and spent 10 years of hiscareer at Boeing troubleshootingpredelivery issues on the B-747, -767, and-777 aircraft. Lie led Boeing support ofnumerous accident investigationsincluding Singapore Airlines B-747Taipei 2000, China Airlines B-747Taiwan 2002, Flash Air B-737 Egypt2004, and Mandala Airlines B-737Indonesia 2005.

Flight Data–The correct interpretation of flight data and/or audio datarequires a full understanding of the entire signal path frommeasurement to recorder to investigator.By Michael R. Poole, Managing Partner, Flightscape, and Simon Lie,Associate Technical Fellow, Boeing Air Safety Investigation

What Every InvestigatorShould Know


In addition, the FCC transmits the value tothe digital flight data acquisition unit(DFDAU).

Continuing to follow the signal chain, wefind that the DFDAU stores the values itreceives from the FCC until the value isscheduled to be written to the FDR. TheFDR writes the value to either magnetictape or solid-state memory as a sequence

of ones and zeros. The data are subse-quently extracted and converted from rawbinary format back into engineering units(i.e., degrees). The converted value is rep-resented as a plot, table, animation, or pos-sibly another format. Finally, the data rep-resentation is interpreted by the accidentor incident investigator.

In theory, each parameter may have its ownunique signal chain.In practice, param-eters that have thesame source oftenshare the same chain—but not always. Ateach step of thechain, there is the po-tential for a change tothe signal. Therefore,each step must befully understood asboth intended andunintended changescan affect the results.

B-737-700exampleOn Jan. 3, 2004,about 02:45:06UTC, 04:45:06 localtime, Flash AirlinesFlight FSH604, aBoeing 737-300,Egyptian registra-tion SU-ZCF,crashed into theRed Sea shortly af-ter takeoff fromSharm el-SheikhInternational Air-port (SSH) in southSinai, Egypt. Theflight was a passen-ger charter flight to

Charles de Gaulle Airport (CDG), France,with a stopover at Cairo International Air-port (CAI) for refueling. Flight 604 de-parted from SSH Airport with 2 pilots (cap-tain and first officer), 1 observer, 4 cabincrew, 6 off-duty crew members, and 135 pas-sengers on board. The airplane was de-stroyed due to impact forces with the RedSea with no survivors.

The airplane had departed from SSHRunway 22R and was airborne at 02:42:33UTC, approximately 2½ minutes prior tothe crash, and had been cleared for a climb-ing left turn to intercept the 306 radial fromSSH VOR station located just north of Run-way 22R.

The FDR and CVR were subsequentlyrecovered from a depth of more than 1,000meters and provided data used during theinvestigation. The airplane began the leftturn but then rolled out of the left turn andinto a right bank that eventually reached110° right bank. A recovery attempt wasmade but was not completed before the air-plane descended into the Red Sea.

The FDR recorded that the departurewas flown with the use of the captain’s andfirst officer’s flight directors in heading se-lect mode. In this mode, the flight directorprovides roll guidance to turn the airplanetoward and hold a “selected heading” setby the flight crew on the mode control panel.Accordingly, investigative attention turnedto the recorded values of selected headingon the FDR.

Figure 2 depicts the airplane heading,selected heading, altitude, and airspeedduring the accident flight. Heading, com-puted airspeed, and altitude are recordedeach second. Selected heading is recordedonce every 64 seconds. Standard practicecalls for setting the selected heading equalto runway heading during take off. At time59 seconds, before the airplane turns ontothe runway, the recorded value of selectedheading was 220° (runway heading) as ex-pected. At time 123 seconds, just prior torotation, the recorded value was 360°.

Later during the flight, the recorded val-

Figure 1. A graphical depiction of the provenance of the selected heading parameterrecorded on a B-737-300 FDR. The data originate in the mode control panel and passthrough a number of distinct transformations before being utilized during aninvestigation.

Figure 2. Altitude, airspeed, heading, and selected headingparameters during the accident flight. Selected heading isrecorded once every 64 seconds. The other three parameters arerecorded every second. The value at time 123 seconds is unusualas a value equal to the runway heading (220°) would be expectedat this phase of flight. The unorthodox arrangement of theheading and selected heading scales (from higher values to lowervalues) is intentional. By convention, parameter values that resultin or result from a right turn tend toward the bottom of the page.The FDR and CVR were subsequently recovered from a depth ofmore than 1,000 meters and provided data used during theinvestigation. The airplane began the left turn but then rolled outof the left turn and into a right bank that eventually reached 110°right bank. A recovery attempt was made but was not completedbefore the airplane descended into the Red Sea.


ues were to the left of the airplane heading,as would be expected during a left turn. The360° value was unusual as the expectedvalue would still be runway heading at thispoint of the takeoff roll. The recorded se-lected heading data could have indicated anunusual procedure by the flight crew, amalfunction of the mode control panel orflight control computer, or something else.Thus, one focus of the investigation was tounderstand the actual reason for the un-usual reading.

When examining unexpected FDR data,a common practice is to use the entire 25-hour record to determine if the unusualbehavior has been present on previousflights. Figure 3 depicts the same four pa-rameters from an earlier flight recorded onthe FDR. The recorded values of selectedheading generally followed the actual head-ing (as expected), but there were repeatedinstances where the two differed and theselected heading was recorded as 360°. Dur-ing some of the times that the 360° valueswere recorded, the airplane was flying on aheading of approximately 315° with the au-topilot engaged in heading select mode.With the selected heading 45° to the rightof the actual heading, the airplane wouldhave been expected to begin a right turntoward 360°. However, no such behavior wasobserved in the recorded data.

Figure 4 depicts a portion of the sameflight as shown in Figure 3 at a different

time scale. The unexpected 360-degree val-ues can be seen to alternate with values co-inciding with the actual airplane heading.

A common practice among DFDAUmanufacturers is to use alternating patternsto indicate errors in the FDR data. For ex-ample, “stale data” occur when a sourcestops transmitting data to the DFDAU orthe transmitted data are not received by theDFDAU. Consultation with the manufac-turer of the DFDAU confirmed that the al-ternating pattern observed in the FDR datafrom the accident flight was an error codeindicating “stale data,” which originated inthe DFDAU. The stale data error code isan alternating sequence of 409510 counts(i.e., 1111111111112) and the last value re-ceived. For selected heading, 409510 countsconverts to 360°, therefore the stale dataerror code consists of recorded values of360° alternating with the last value received.If the inquiry had ended here, one mightconclude that the FCC had malfunctionedas evidenced by the apparent lack of se-lected heading transmission to the DFDAU.Such a conclusion would be incorrect.

In addition to the 25 hours of FDR dataavailable from the accident airplane, theEgyptian MCA provided 25 hours of FDRdata from the sister ship. An examinationof that data confirmed the same behavior—selected heading occasionally alternatedbetween an expected value and 360°. Asshown in Figure 5, the same behavior was

also discovered in the selected course #1parameter on both airplanes but not in theselected course #2 on either airplane. Basedon these discoveries, the possibility arosethat some sort of design characteristic wasresponsible for the observed data. Perhapsthere was some difference in the way theselected heading and selected course #1parameters were processed compared tothe selected course #2 data that would ex-plain the anomaly.

Accordingly, the inquiry focused on howthe DFDAU detected stale data. Accord-ing to the DFDAU manufacturer, stale dataare detected as follows:• The DFDAU uses an 8-bit counter to trackthe number of data samples it has receivedfrom the source (in this case the FCC).• When scheduled to write a value to theFDR, the DFDAU compares the value ofthe counter to the value of the counter thelast time a sample was sent to the FDR.• If either the counter value or the datavalue is different, the DFDAU concludes thedata are fresh. If both the counter value andthe data value are the same, the DFDAUconcludes the value is stale. After three con-secutive stale samples, the DFDAU beginswriting the stale data error code until ei-ther the counter value or data value change.

Consulting with the FCC manufacturer,it was determined that selected heading andselected course #1 were transmitted to theDFDAU at a rate of 20 Hz. Thus, the

Figure 3. Altitude, airspeed, heading, and selected headingparameters during an earlier flight. Although selected headinggenerally follows actual heading as would be expected, thereare repeated instances where unexpected values of 360° arerecorded.

Figure 4. A portion of the same flight depicted in Figure 3 (notechange in time scale). The unexpected 360° values of selectedheading alternate with values coinciding with the actualairplane heading (expected values).


DFDAU received selected heading dataonce every 50 ms and transmitted it onceevery 64 seconds—a ratio of 1,280 to 1. Incontrast, selected course #2 was transmit-ted by the FCC (and received by theDFDAU) at a rate of 10 Hz for a ratio of

640 to 1.Figure 6 depicts

the behavior of the 8-bit counter when uti-lized for selectedcourse #2 (receive totransmit ratio of 640to 1). The capacity ofan 8-bit counter is 0-255 or 256 distinct val-ues. During normaloperation, the 8-bitcounter will reach itsmaximum value and“roll over” back tozero at least twice andpossibly three timesas the 640 samplesare received by theDFDAU betweeneach sample trans-mitted to the FDR.Regardless of thevalue of the counterwhen a sample is

transmitted, the counter will be at a differ-ent value (that differs by approximately 128from the previous value) when the nextsample is transmitted. The result is that theDFDAU can correctly determine if the dataare fresh or stale.

Applying the same analysis to selectedheading and selectedcourse #1 yields adifferent result. Fig-ure 7 depicts the situ-ation when the ratioof receive-to-trans-mit interval is 1,280to 1. In this case, thecounter rolls over ex-actly five times be-tween each transmit-tal to the FDR. Nor-mal operation willresult in the countervalue being the samewhen successivesamples are trans-mitted to the FDR.If the parametervalue has notchanged, theDFDAU will incor-rectly detect that thedata are stale, eventhough the correctnumber of samples(1,280) has been re-

ceived.The anomalies in the selected heading

and selected course #1 parameters oc-curred frequently but not in every instanceduring which the above conditions are met.The last step in the inquiry determined thatthe exact receive-to-transmission ratio de-pended upon the relative timing betweenthe FCC internal clock and the DFDAUinternal clock, known as jitter. Occasionally,the DFDAU would detect 1,279 or 1,281samples instead of 1,280 in which case thedata would be treated as fresh.

Once the behavior of the stale data de-tection algorithm was understood, it was asimple matter to correct the FDR data toaccurately reflect the selected heading val-ues transmitted by the FCC. The DFDAUwill only detect stale data if the parametervalue itself is unchanged. Therefore, it waspossible to conclude that the selected head-ing transmitted by the FCC that resultedin the 360° value recorded on the FDR musthave been the same as the previously re-corded value—220, the runway heading.The investigation concluded that theanomaly in the stale data detection capabil-ity of the DFDAU was responsible for theunexpected value of selected heading re-corded on the FDR and that the actual valueof selected heading at this time was 220°.The corrected value shown in Figure 8 (seepage 30) depicts the data used for the analy-sis portion of the investigation.

As often occurs, this investigation uncov-ered a finding not related to the accidentitself—that the DFDAU did not correctlyprocess data when the receive interval-to-transmit interval ratio was a multiple of 256.A full understanding of the provenance ofthe FDR data allowed for the correct in-terpretation of that data for subsequent usein the analysis of the accident.

Every investigator or analyst who usesflight data should know that the correctinterpretation of flight data requires a fullunderstanding of the provenance of thedata. Each step in the signal chain frommeasurement to transmission, recording,decoding, conversion, and the final repre-sentation can introduce unintendedchanges and thus the potential for error.The example discussed above demon-strates unintended changes introduced onboard the accident aircraft. Such unin-tended changes can also occur during thesubsequent recovery and conversion pro-cesses. Determining the provenance of

Figure 6. Behavior of an 8-bit counter when the receive-to-transmit interval is 640 to 1 as is the case for selected course#2. The capacity of an 8-bit counter is 2565. During normaloperation, the counter will “roll over” twice (or possibly threetimes) between each transmission. Regardless of the value ofthe counter when a sample is transmitted, the counter will be ata different value (that differs by approximately 128 from theprevious value) when the next sample is transmitted with theresult that the DFDAU correctly detects that the data are fresh.

Figure 7. Behavior of an 8-bit counter when the receive-to-transmit interval is 1,280 to 1 as is the case for selectedheading and selected course #1. The counter will roll overexactly five times between each transmission. The result is thatthe DFDAU incorrectly detects that the data are stale duringnormal operation.

Figure 5. Similar to selected heading, unexpected values of360° were also observed in the selected course #1 parameterbut not in selected course #2. All three parameters are re-corded once every 64 seconds. FDR data from the accidentsairplane’s sister ship exhibited the same unexpected values inthe selected heading and selected course #1.

(continued on page 30)


ISASI ROUNDUP

‘Investigation: The Art and the Science’○

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ISASI 2008, the Society’s 39th annualinternational seminar on air accidentinvestigation, is now open for registration,according to Barbara Dunn, seminarchairperson and president of the Cana-dian SASI (CSASI), which is hosting theevent to be held in Halifax, Nova Scotia,September 8-11. In addition, the SeminarCommittee is honoring the 100th anniver-sary of the construction of the Silver Dartthrough its representation in the ISASI2008 logo. The aircraft, credited withcompleting the first controlled powerflight in Canada and the British Empire,was built in 1908 by the Aerial Experi-ment Association chaired by Dr.Alexander Graham Bell. John A.D.McCurdy piloted the historic flight onFeb. 23, 1909.

The seminar program registration fee(in U.S. dollars) by August 10, is member,$525; student member, $200; non-member,$570. If registration is made after August10, the fees are $575, $225, and $625,respectively. Day pass fee for any of thethree days is $200 by August 10, afterthat date $225. The member fee for eitherof the two September 8 tutorials is $125by August 10 and $150 after that date;student member, $75 and $100. Thecompanion fee is $320 by August 10 and$350 after that date. Registrationcancellations made before July 10 willincur a $10 fee. Cancellations betweenJuly 27 and August 10, will incur a $75fee. There will be no refund of fees forcancellations after August 10.

The Canadian Society has established adetailed and easy-to-manage websiteaccessible through the ISASI website,www.isasi.org. All areas of delegateinterest are easily identified and accessedon the site. A seminar registration formmay be found on the website and it maybe submitted electronically. A copy of theseminar registration form is also re-printed on page 25. Either registrationform may be downloaded or clipped outand mailed to ISASI Seminar Registra-

tion, P.O. Box 16032, Albuquerque, NM,87191 USA.

The seminar will be held at the HalifaxMarriott Harbourfront Hotel. The ISASIdelegate room rate is $185 Canadian foreither a single or double and is subject totaxes. The special rate is valid to August 7and is available from September 2-16. Noprovisions exist for special rates onupgrade rooms. Rated as a AAA 4-Diamond hotel, it is situated in the heartof downtown, only steps away from thecity’s top attractions, including thebusiness district and World Trade &Convention Center. The hotel is knownfor its upgraded business amenities, aswell as 17,000 square feet of flexiblemeeting and social-event space. Delegatesshould deal directly with the HalifaxMarriott regarding their accommodationarrangements. The hotel registrationform is available through a link accessedthrough the ISASI 2008 seminar website(www.isasi.org).

Program planThe seminar program will follow theestablished format of past seminars, with1 day devoted to two tutorial workshopsand 3 days of technical paper presenta-tions in plenary session. National society,committee, and working group meetingswill also be scheduled. ISASI 2008 carriesthe theme “Investigation: The Art andthe Science,” that, says Jim Stewart,technical program chairman, “reflects thecomplexity and challenge of today’sinvestigation process. As science advancesaviation technology, that same science

introduces the need for new techniquesand support systems to ensure a compre-hensive and professional investigation.The art of successful investigationrequires the creative application ofpersonal knowledge and skills and thedevelopment of new concepts to keep pacewith a rapidly changing industry worldwide.”

He adds, “The Seminar Committee waslooking for papers that would deal with thehard and soft aspects of investigation, inparticular, new ideas that will lead us toimproved investigation whether it istechniques, management, process,technology, factual analysis, high tech orlow tech. The subject matter could be asbroad as the imagination or expertise ofthe presenter. The Technical Committeewanted to reach beyond the normal papersand explore new ideas. We were also veryinterested in hearing from full-timeinvestigators or agencies that have recentexperience with new techniques orprocesses and their experience in applyingthem. Some ‘soft side’ subjects we wereinterested in were subjects ranging fromdealing with the news media, relatives, andinterview techniques.”

The Committee has received more than40 proposals for papers from a number ofqualified speakers on a wide range ofsubjects. About 25 of these proposals willbe presented in Halifax following athorough assessment by the ISASI 2008Papers Selection Committee, whichreflects the international aspect of ISASI.Joining Stewart as members of theCommittee are Barbara Dunn (Canada),Seminar Committee chair; Nick Stoss(Canada), tutorial chair; Ron Schleede(USA); Marcus Costa (ICAO); ClaudioPandolfi (Chile); Wing Keong Chan(Singapore); Danny Ho (Taiwan); MartineDel Bono (France); David King (UK); andMichael Walker (Australia).

The 1-day tutorial sessions will includetwo workshops. The first will center onSafety Management Systems and the


Please Complete All Areas as Appropriate Is this Your First Seminar? ❏ Yes ❏ No

ISASI Member? ❏ Yes ❏ No If yes, please complete the member information below:

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39th Annual International Society ofAir Safety Investigators SeminarSept. 8–11, 2008, Marriott Harbourfront Hotel, Halifax, Nova Scotia, Canada

Delegate Registration Form and Fee Summary (US$)Yes, please register me for the 39th Annual International Society of Air Safety Investigators Seminar! You can register bye-mailing, mailing, or faxing this completed form to the information below. Please complete one form for the primary individual attending. Exhibitors andcompanions have a separate registration form. Note: Please print all information on this form. This form may be reproduced as necessary. Cancellations madebefore July 10, 2008, will incur a $10 fee. Cancellations between July 27, 2008, and Aug. 10, 2008, will incur a $75 fee. There will be no refund of fees if cancelledafter Aug. 10, 2008. However, substitutions are permitted at any time. Make sure to include the fees for any optional programs in the total amount being paid.

Registration type Before Aug. 10 After Aug. 10❏ ISASI member US$525 US$575❏ ISASI student member US$200 US$225❏ Not an ISASI member US$570 US$625Delegate nominated by sponsor (free)

The above registration includes the reception (Mon.), fun night (Tues.), andbanquet (Thurs.). Please check below if not attending:❏ Reception ❏ Fun Night ❏ Banquet❏ Day pass only (per day) US$200 US$225Check day(s): ❏ Tuesday ❏ Wednesday ❏ Thursday❏ Banquet only (US$100) ❏ Tuesday fun night (US$100)❏ Welcome reception (Monday) (US$90)

Optional programs Before Aug. 10 After Aug. 10❏ Tutorial (Monday, Sept. 8) US$125 US$150❏ Tutorial (student member) US$275 US$100Please select one tutorial:

❏ Tutorial #1—Conducting Safety Investigations in aSafety Management (SMS) Environment

❏ Tutorial #2—Investigating General Aviation Accidents

❏ Companion Program(per person) US$125 US$150Note: Please fill out the Companion registration for each companion.# of Companion Programs ______

Billing information

❏ Charge my credit card: ❏ AmEx ❏ VISA ❏ MasterCard Name on card _________________________________________________________

Card number _____________________________ Expiration date ___________________________ Card code ________________________________

❏ Send by mail: ❏ Payment by check ❏ Company purchase order P.O. # _______________________________________________________________

TOTAL IN US$ _____________________Note: Credit card name must be listed on the card. Card billing address must match address listed above in registration. The card code is a four-digitnumber on the front of an American Express card or a three-digit number on the back of a VISA or MasterCard.

Mail to: ISASI Seminar RegistrationP.O. Box 16032, Albuquerque, NM 87191 USA

TEL: +1 (888) 292-2129 (US and Canada)TEL: +1 (505) 299-1690

FAX to: +1 (505) 292-2017E-mail to: [email protected]

Signature (required for credit card)________________________________________________________________________________

✁


Continued . . .

ISASI ROUNDUP

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second will deal with investigating generalaviation accidents.

Tutorial No. 1, “Conducting SafetyInvestigations in a Safety ManagementSystems (SMS) Environment,” will seekto answer the questions “What will theimpact of SMS be on safety investiga-tions?” and “How do we investigate underthe shadow of SMS?” The seminarwebsite contains more information on thecontents of the tutorials.

Social programsIn keeping with ISASI tradition, theseminar social program will start with awelcome reception on Monday evening,September 8. This is an ice-breaker social,providing an opportunity to meet with oldand new friends. On Tuesday evening aspecial dinner is planned that will allowattendees to experience some Canadianhistory at the Pier 21 National HistoricSite. This Canadian equivalent to EllisIsland welcomed newcomers to Canadafrom 1919 to 1972. Immigration data-bases, tourist information, and gift andcoffee shops are a few of the attractionsthat await guests at the Chrysler CanadaWelcome Pavilion. Guests will enjoy areception in Exhibition Hall before beingseated in Heritage Hall for a traditionalEast Coast lobster dinner.

Wednesday evening will be a free nightpermitting attendees to explore the manyfine restaurants found in Halifax. TheAwards Banquet, at which ISASI’sJerome F. Lederer Award presentation ismade, will be held on the Thursdayevening at the Harbourfront Marriott.The usual post-seminar optional tour onFriday is not being offered.

Companion’s ProgramThe Companion’s Program, organized byGail Stewart and Paula Demone, includesa deluxe Halifax City tour on Tuesday anda visit to the South Shore on Wednesday.Both are all-day tours and promiseexciting historical narratives. Kilted

guides will no doubt relate stories of thedays of rum running and privateering asthey move through the city streets onTuesday. The tour will travel toFisherman’s Cove for a two-course lunchenhanced by views of Nova Scotia’sEastern Passage.

On Wednesday, the group will tour therugged and beautiful South Shore ofNova Scotia. The first stop isLunenburg, which has been called “theprettiest town in Canada.” Settled in themid 1750s by Germans and Swiss, itscitizens still retain one of the mostinteresting accents in North America.Now a bustling fishing port, the town’sdistinctive architecture and extraordi-nary scenic beauty are a colorfulreminder of its maritime heritage.

After lunch at Lunenburg’s The OldFish Factory comes a quick stop atMahone Bay with its many cottageindustries, craft shops, and famous“Three Churches.” Then it is on toPeggy’s Cove, an artists’ and explorers’paradise for well more than 150 years.This picture-postcard village stands onsolid rock above the crashing surf. Thecoastline is famous for pirates, ship-wrecks, rum running, and sunsets. Fulldetails of the Companion’s Program areavailable on the ISASI 2008 website.

Nova Scotia fast factsCapital city—Halifax RegionalMunicipality.Population—Halifax Regional Munici-pality 382,203, Nova Scotia 934,405.Languages—The official languages ofEnglish and French are spoken through-out Nova Scotia.Time zone—Nova Scotia is on AtlanticDaylight Time, which is 4 hours earlierthan Greenwich Mean Time and 1 hourlater than North America’s Eastern TimeZone. Daylight Saving Time took effectthe second Sunday of March and contin-ues to the first Sunday of November. Climate and weather—Average daily

temperatures in spring are from 2° to 9° C(35.6° to 48.2°F); summer from 16° to 24° C(60.8° to 75.2°F); fall about 18° C (64.4°F);winter about -3° C (26.6°F). Weatherforecasts are given in Celsius measure-ments. For approximate temperatureconversion: Fahrenheit to Celsius: subtract30 and divide by 2. Celsius to Fahrenheit:multiply by 2 and add 30. Airports—Most air traffic comes throughHalifax Stanfield International Airport,which is the Atlantic Canadian center fordomestic, regional, and internationalflight service. With more than 600 flightsa week, travelers can reach Halifax ondirect flights from many Canadian, U.S.,European, and Caribbean destinations.Air carriers serving Halifax include AirCanada, Air Canada Jazz, WestJet,Continental Express, Delta, United,Northwest, American Eagle, Air St.Pierre, Condor, Zoom, Go Travel DirectVacations, Provincial, Sunwing, andSkyservice.Customs and immigration—Immigra-tion regulations: American citizens (orpermanent residents) entering Canada byair require valid passports, and as ofJanuary 31 valid passports are requiredwhen entering by land and sea. Visitorsfrom a country other than the UnitedStates must carry a valid passport and, incertain cases, a visa to be eligible to enterCanada. All persons entering Canadamust fill out a declaration for CanadaCustoms. Currency—Canada’s currency is basedon the decimal system, with 100 cents tothe dollar. Sales tax and rebates—The harmonizedsales tax (HST) is applied at a single rateof 13% to a base of goods and services.Foreign visitors may be entitled to claim arebate of the HST paid. Accommodationsin Halifax charge a hotel levy of 2% onroom rates to assist in marketing Halifaxas a business and leisure destination.Hospital/medical services—Visitors toCanada are strongly urged to obtain


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2007 Annual Seminar Proceedings Now Available

Active members in good standing andcorporate members may acquire, on ano-fee basis, a copy of the Proceedingsof the 38th International Seminar,held in Singapore Aug. 27-30, 2007, bydownloading the information from theappropriate section of the ISASI web

Preface: Welcome to SingaporeBy Frank Del Gandio, President, ISASIOpening Address: Importance of Interna-tional Cooperation in Aircraft AccidentInvestigationBy Raymond Lim, Minister for Transportand Second Minister for Foreign Affairs,SingaporeKeynote Address: Sharing ExperienceAnd KnowledgeBy Mark V Rosenker, Chairman, U.S.National Transportation Safety BoardLederer Award Recipient: ‘Independenceand Integrity’ Mark Tom McCarthyBy Esperison Martinez, Editor

SESSION 1—Moderator David McNairRoyal Australian Navy Sea King AccidentInvestigation—Indonesia April 2, 2005By Nicholas Athiniotis and DomenicoLombardo, Defence Science and TechnologyOrganization, AustraliaRussia/France: Safety and CulturalChallenges in International InvestigationsBy Alexey N. Morozov, Interstate AviationCommittee and Sylvain Ladiesse, BEAInternational Cooperation Paves theRunway for a Safer SkyBy Guo Fu, East China Administration,CAAC

SESSION 2—Moderator Sue BurdekinWinter Operations and Friction Measure-mentsBy Knut Lande, Accident InvestigationBoard, NorwayUtilization of the Web-Based GIS to AssistAviation Occurrence InvestigationBy Tien-Fu, Yeh, Wen-Lin Guan, and HongT. Young, Aviation Safety CouncilUse of Reverse Engineering Techniques toGenerate Data for InvestigationsBy Peter Coombs, AAIB, UK

SESSION 5—Moderator Danny HoInternational Cooperation and Challenges:Understanding Cross-Cultural IssuesBy Dr. Wen-Chin Li, National DefenseUniversity; Dr. Hong-Tsu Young, Taiwan,ASC; Thomas Wang, ASC; and Dr. DonHarris, Cranfield UniversityVery Light Jets: Implications for SafetyAnd Accident InvestigationBy Dr. Robert Matthews, Ph.D., FAAEnhanced Airborne Flight Recorder(EAFR)—The New Black BoxBy Jim Elliot, G.E. AerospaceRSAF: Analysis and Investigation; Toolsand TechniquesBy Lt. Col. Suresh Navaratnam, Republic ofSingapore Air Force (RSAF)Wet Runway Accidents—The Role ofFatigue and Coercive HabitsBy Capt. A. Ranganathan

SESSION 6—Moderator David KingISASI International Working Group onHuman Factors: A Progress ReportBy Capt. Richard Stone, ISASI and Dr.Randy Mumaw, BoeingInternational Coorperation During RecentMajor Aircraft Accident Investigations inNigeriaBy Dennis Jones, NTSBCritical Aspects of International IncidentInvestigationsBy Deborah J. Lawrie, Robert N. van Gelder,and Jan Smeitink, Independent SafetyInvestigation & Consultation ServicesNational Transportation Safety Commit-tee of Indonesian PresentationBy Tatang Kurniadi, Chairman, NationalTransportation Safety Committee, IndonesiaGoing the Extra MileBy Donald F. Knutson (Accepted forpresentation, but not orally delivered due toexigent circumstances.) ◆

page at http://www.isasi.org. The seminarpapers can be found in the “Members”section. Alternatively, active membersmay purchase the Proceedings on a CD-ROM for the nominal fee of $15, whichcovers postage and handling. Non-ISASImembers may acquire the CD-ROM for a

US$75 fee. A limited number of papercopies of Proceedings 2007 areavailable at a cost of US$150. Checksshould accompany the request and bemade payable to ISASI. Mail to ISASI,107 E. Holly Ave., Suite 11, Sterling,VA USA 20164-5405.

Using Checklists as an Investigator’s ToolBy Al Weaver

SESSION 3—Moderator Alan StrayFinding Nuggets: Cooperation Vital in Effortsto Recover Buried DataBy Christophe Menez and Jérôme Projetti, BEAInternational Investigation: General AviationAccident in Atlantic WatersBy Joseph Galliker, ASC International, Inc.Standardizing International Taxonomies forData-Driven PreventionBy Corey Stephens, Air Line Pilots Association;Oliver Ferrante, BEA; Kyle Olsen, FAA; andVivek Sood, FAAMidair Collision Over Brazilian Skies—A Lesson to Be LearnedBy Col. Rufino Antonio da Silva Ferreira, JoséMounir Bezerra Rahman, and Carlos EduardoMagalhães da Silveira Pellegrino, BrazilianAeronautical Accident Investigation Commis-sion (CENIPA); William English, NTSB; andNick Stoss, TSB Canada

SESSION 4—Moderator Richard BreuhausConvair 580 Accident Investigation: A Study inSynergyBy Ian McClelland, TAIC, New ZealandTenerife to Today: What Have We Done in30 Years To Prevent Recurrence?By Ladislav Mika, Ministry of Transport, CzechRepublic, and John Guselli, JCG AviationServicesFlight Data: What Every InvestigatorShould KnowBy Michael Poole, Flightscape, Inc., and SimonLie, BoeingSound Identification and Speaker Recogni-tion for Aircraft Cockpit Voice RecorderBy Yang Lin, Center of Aviation SafetyTechnology, CAAC and Wu Anshan and LiuEnxiang, General Administration of CivilAviation of China, CAAC

health insurance before leaving theirhome country. Canadian hospital andmedical services are excellent, but ahospital stay can be costly withoutadequate insurance coverage. Visitorstaking prescribed medications are advisedto take a copy of the prescription should itneed to be renewed during the trip. ◆

ISASI Reachout Enters 8thYear in Need of FundsIt may seem hard to believe but on May 7,the ISASI Reachout program enters itseighth year of operation. During thattime, volunteer instructors have delivered25 successful workshops around the

world. Ladislav Mika, the first host, andPrague, the Czech Republic, where thefirst workshop was held in May 2001, willforever be linked to the success of theReachout program.

The past 12 months saw a flurry ofactivity as ISASI instructors traveledextensively around the world—


Continued . . .

ISASI ROUNDUP

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New Members

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• Reachout #21 Kiev, Ukraine, October2007• Reachout #22 Santiago, Chile, Novem-ber 2007• Reachout #23 Karachi, Pakistan, No-vember 2007• Reachout #24 Abu Dhabi, UAE, Novem-ber 2007• Reachout #25 Brisbane, Australia,March 2008

Currently scheduled workshopsinclude—• Reachout #26 Seattle, USA, April 2008• Reachout #27 Mumbai, India, April2008• Reachout #28 Bahrain, UAE, May2008• Reachout #29 Karachi (Unscheduled)

But ISASI Reachout Committeechairman, Jim Stewart, sees problems inthe future for the Reachout program iffunds are not received to replenish themain Reachout account. “We have beenvery successful in obtaining localsponsorship for individual workshops,”Stewart said recently. “We have beenparticularly blessed with dynamicindividuals volunteering to host ourworkshops and with national andregional airlines providing air travel.”Stewart pointed out that their supporthas been considerable in many cases andwithout that support the program couldnot have been able to sustain the level ofactivity it has to date. He concluded,“But our ability to support our instruc-tors is not as strong as I would like.

“We need to top up our emergencyfund to ensure that our instructors arenot paying their own way,” Stewart said.“That Reachout fund is kept in a separateaccount at the ISASI head office. We usethat fund to reimburse instructors whenlocal sponsors can not cover all of theassociated costs,” Stewart pointed out,“and that fund is running dangerously lowas a result of our activity levels.” Stewartalso pointed out that access to theemergency funds is strictly controlled

CORPORATEFinnish Military Aviation Authority

Major (Eng.) Kimmo T. Nortaja, LeadingAviation Accident Investigator

Mikko T. Hietanen, Chief of FAIFFlight Safety

Northwest AirlinesLisa G. Brockenbrough, Director, Flight

Safety and Industry AffairsTodd Tilbury, Manager, Flight Safety

Dombroff Gilmore Jaques & French P.C.Mark A. Dombroff, Managing PartnerDane B. Jaques, Partner

General Aviation Manufacturers AssociationW. Casey Kinosz, Manager of OperationsJens C. Hennig, Vice-President

of Operations

INDIVIDUALAdkins, John, M. ,Daytona Beach, FL, USAAl Marzouqi, Fouad, B., Abu Dhabi, United

Arab EmiratesAl Said, Saud, T., Sharjah, United Arab

EmiratesAl-Awadhi, Kamil, H., Quadsiah, KuwaitAlegado, Jaime, V., Doha, QatarAnglin, Lori, M., Renton, WA, USAAwbery, Natalie, Godalming, Surrey,

United KingdomBalentine, Chad, J., Winchester, VA, USABarros, Andrés, Santiago, ChileBarth, Thomas, H., Denver, CO, USABenassi, Stefano, VR, ItalyBonnassie, Fabien, Montreuil, FranceBoyd, Rodney, L., Wylie, TX, USACabel Francis, Abu Dhabi, United Arab

EmiratesChen, Felix, S.K., SingaporeChiang, Vin, C., Daytona Beach, FL, USAde Kock, André, L., Montréal, CanadaDe La Vauvre, Gaetan, Evanston, IL, USADe Waal, Johan, G., Abu Dhabi, United

Arab EmiratesDecatur, Danielle, M., Ocean, NJ, USADyer, Brian, R., Daytona Beach, FL, USAEisenman, Nathaniel, B., Manassas, USAElgindi, Hisham A. Aziz, Abu Dhabi,

United Arab EmiratesEngroba, Juan, D., Buenos Aires, ArgentinaFarmiga, Samuel, R., West Chester, OH, USAFragoso, Jefferson, V., Sao Paulo, BrazilFranklin, Ryan, H., Ormond Beach, FL, USAGipson, Paul, Scottsdale, AZ, USAGoetz, Jean-Baptiste, Abu Dhabi, United

Arab EmiratesGraydon, Mike, Abu Dhabi, United Arab

EmiratesHolland, Dennis, A., Northamptonsire,

United Kingdom

Houston, Mark, D., Hawkes Bay,New Zealand

Husain, Muhammad, M., Arad, Kingdomof Bahrain

Jackson, Robert, J., Issaquah, WA, USAJay, Susan (Sue), M., Orange Park, FL, USAKelman, Sarah, J., Cambridge, United

KingdomKunteson, Randall, R., Deatsville, AL, USAKwajan, Francis, A., Grand Central Station,

NY, USALabrucherie, Stephan, Abu Dhabi, United

Arab EmiratesLammas, Janet, I., Wellington, New ZealandMayfield, Richard, F., Renton, WA, USAMiller, Andrew, B., Christchurch,

New ZealandMiranda, Ray, M., Kajang, West MalaysiaMoussa, Ali, M., Beirut, LebanonNaseer, Ahsan, Abu Dhabi, United Arab

EmiratesNitta, Takashi, Toyonaka, Osaka, JapanNoe, II, Ronald, E., Wichita, KS, USANutter, Christopher, G., Federal Way,

WA, USAOrdor, Maria, U., Mafoluku-Lagos, NigeriaPinzón Müller, Eduardo, Bogota, Colombia,

South AmericaPooley, Edward, J., Isle of Man, British IslesQarashi, Baha, G., Abu Dhabi, United

Arab EmiratesRichter, Mark, W., Hanover Park, IL, USARigby, Kevin, T., Pensacola, FL, USARivera-Martinez, Alimael, Prescott Valley,

AZ, USARogachuk, Ted, M., Bay Village, OH, USARonaldson, George, Aberdeen, United

KingdomRoss, Cameron, C., Southlake, TX, USASatti, Juan, A., Castelar, ArgentinaSavage, Eric, R., Prescott, AZ, USASchonhardt, Carlos, F.G., Rio De Janeiro,

BrazilSenthil, M.S., Gopalakrishnan, Seeb Int’lAirport, Sultanate of OmanShappee, Eric, H., Salina, KS, USAShearer, Daniel, J., Daytona Beach, FL, USASkoor, Erich, J., Prescott, AZ, USASmith, Sean, J., Daytona Beach, FL, USAStauffer, Kent, M., Stow, OH, USATalay, James, E., Mission Viejo, CA, USATorres, Roberto, H., Ormond Beach,

FL, USATrono, Peter, J., Pearblossom, CA, USAYusof, Mohd Hisham Md., Abu Dhabi,

United Arab EmiratesZanolli, Stefano, Roma, ItalyZwager, Finn, Dubai, United

Arab Emirates ◆

with both he and the ISASI treasurerhaving to jointly approve expendituresbefore the fact.

ISASI Reachout was originallyconceived as a way for ISASI corporatemembers to participate in the work of theSociety. To a great extent, some ISASImember corporations have responded inkind and provide access to airline seats,free access to documents and manuals,

use of organizational materials and staff,and many other small and large contribu-tions. Stewart said, “Without the contin-ued support of sustaining organizationslike ICAO, the Air Line Pilots Associa-tion, and Continental Airlines, our jobwould be much more difficult.”

ISASI Reachout needs to increase thenumber of sustaining sponsors and needsto receive additional “one time” donations


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MOVING?Please Let Us KnowMember Number_____________________

Fax this form to 1-703-430-4970 or mail toISASI, Park Center107 E. Holly Avenue, Suite 11Sterling, VA USA 20164-5405

Old Address (or attach label)

Name _____________________________

Address ___________________________

City _______________________________

State/Prov. _________________________

Zip _______________________________

Country ___________________________

New Address*

Name _____________________________

Address ___________________________

City _______________________________

State/Prov. _________________________

Zip _______________________________

Country ___________________________

E-mail ____________________________

*Do not forget to change employment ande-mail address.

from a broader base of corporations.“When we started the Reachout program,we established a one-time CharterSponsor category for original sponsors,”Stewart said.

“We can’t bring that category back, butwe will create a new category, ‘SustainingSponsor,’” he said. “Sustaining Sponsorsare those sponsors we can count on to bethere when needed throughout the year.”

For those corporations or individualswho wish to contribute to the Reachoutprogram, even a one-time contributionwill help, no matter how large or small.Contributions should be payable to ISASIReachout and sent to ISASI headquar-ters at Park Center, 107 East Holly Ave.,Suite 11, Sterling, VA, 20164-5405.

In a final comment, Stewart againthanked the instructors, the local hosts,and the current Sustaining Sponsors fortheir continued support. “They are thereason we are here today,” he said. “Theircontribution has been large, theircommitment strong. You can help byjoining the ISASI Reachout sponsorshipgroup as a ‘Sustaining Sponsor’ or a one-time contributor. Make your contributiontoday,” he concluded. ◆

Arizona ChapterContinues ExpansionThe student section of the Arizona chaptercontinues to expand. Chapter PresidentBill Waldock says, “We currently have 16active members, with a big push for themto join the International Society. Currently,the students meet every 2 weeks in theRobertson Aviation Safety Center atEmbry-Riddle’s Prescott Campus. Wehave had several guest speakers, includingProf. Denny Lessard and FAA Mainte-nance Inspector Pete Kelly.”

In November 2007, the Chapter

sponsored a presentation to the campusby retired NTSB senior air safetyinvestigator Greg Feith. Members fromthe Chapter have been assisting regularlyin maintaining and refurbishing accidentscenarios in the Aircraft AccidentLaboratory. The Chapter is sponsoring atrip to Williams-Gateway Airport in Mayfor those members who would like toexperience an altitude chamber ride. Thestudent section has just held officerelections, and Erich Skoor (ST5519) willbe the new president.

On Nov. 16, 2007, the Chapter con-ducted an expedition to the World War IIB-24 crash site on Humphries Peak nearFlagstaff, Ariz. This was the singlelargest trip to the crash site, with 35people participating. The aircraft crashedduring a night training mission inSeptember 1944. All eight airmen aboardwere killed. The wreckage is locatedbetween 11,000 and 11,500 feet on themountain and, due to the terrain, isdifficult to access.

Most of the wreckage is still there, andone of the long-term projects the ArizonaChapter has undertaken is to conductperiodic surveys of the wreckage layoutand positions of major pieces.

Waldock says, “We have been up therefive previous times, but this time we had avery significant occurrence. Our studentsection president, Cavi Freeland, washelping examine an area where compo-nents from the front of the fuselage hadbeen identified. She noticed an odd piecejust below the surface of the soil andteased it up with a finger. It was a goldairmen’s style ID bracelet piece with thename ‘Ray Shipley’ engraved on one sideand ‘DRU’ on the other. The crewmanifest shows Flight Officer RayShipley as the ‘second pilot’ on theaircraft. Research has shown that hiswife’s name was “Drucilla” and that hehas living relatives in Garland, Tex. CraigFuller of Aviation Archaeology Investiga-tion and Research has assisted with the

provenance and record search by whichwe have been able to document what isknown about this long-lost young pilot.We are currently making plans to returnthe ID to Shipley’s family.”

New Book Outlines‘The Limits of Expertise’The Limits of Expertise: RethinkingPilot Error and the Causes of AirlineAccidents, by ISASI member Dr. LoukiaLoukopoulos and coauthors Benjamin A.Berman and R. Key Dismukes, arguesthat human skill and vulnerability to errorare closely linked.

In paperback, it is 352 pages, published

REMINDER

ISASI annual dues were due inJanuary. For those members whomay not have yet made the pay-ment, please contact Ann Schull [email protected] or call 703-430-9668 to make payment arrange-ments. If payment is not received,the affected member will be placedin an inactive status. ◆


ISASI Information

OFFICERSPresident, Frank Del Gandio

([email protected])Executive Advisor, Richard Stone

([email protected])Vice-President, Ron Schleede

([email protected])Secretary, Chris Baum

([email protected])Treasurer, Tom McCarthy

([email protected])

COUNCILLORSAustralian, Lindsay Naylor

([email protected])Canadian, Barbara Dunn

([email protected])European, Anne Evans

([email protected])International, Caj Frostell

([email protected])New Zealand, VacantUnited States, Curt Lewis

([email protected])

NATIONAL AND REGIONALSOCIETY PRESIDENTSAustralian, Lindsay Naylor

([email protected])Canadian, Barbara M. Dunn

([email protected])European, David King

([email protected])Latin American, Guillermo J. Palacia

(Mexico)New Zealand, Peter Williams

([email protected])Russian, Vsvolod E. Overharov

([email protected])SESA-France Chap.,Vincent Fave

([email protected])United States, Curt Lewis

([email protected])

UNITED STATES REGIONALCHAPTER PRESIDENTSAlaska, Craig Bledsoe

([email protected])Arizona, Bill Waldock

([email protected])Dallas-Ft. Worth, Curt Lewis

([email protected])Florida, Ben Coleman

([email protected])Great Lakes, Matthew Kenner

([email protected])Los Angeles, InactiveMid-Atlantic, Ron Schleede

([email protected])Northeast, David W. Graham

([email protected])Pacific Northwest, Kevin Darcy

([email protected])Rocky Mountain, Gary R. Morphew

([email protected])San Francisco, Peter Axelrod

([email protected])Southeastern, Inactive

Flight Data—What Every Investigator Should Know (from page 23)

Figure 8. The same data as depicted in Figure 1 corrected toaccount for the anomaly discovered in the way the DFDAUprocessed the selected heading data. These were the data usedfor the analysis portion of the investigation.

each parameter andunderstanding thecapabilities and re-play processes with-in the analysis soft-ware is a necessarystep in interpretingflight data. ◆

(Space restrictionsrequired deletionfrom the authors’presented papertheir discussiondealing with theprocessing of flightdata through twomethods: Convert-ing the binary onesand zeros into engi-neering units dataand producing com-ma separated vari-ables files and inter-actively working with the binary data on ademand basis. The unused material may

be viewed on the ISASI web page in Pro-ceedings 2008, page 95.—Editor)

by Ashgate Publishing Company. It isavailable through Amazon.com, wheresufficient reviews are also posted. One ofthose reviews, by Benjamin Daley, cites itas an “Outstanding and original book…that show[s] that the presence and inter-action of factors contributing to error isprobabilistic rather than deterministic.”

Stephen Wilkinson in his review of thebook published in Air and Space maga-zine noted that the book “simply examinesthe 19 serious accidents suffered by majorU.S. air carriers between 1991 and 2000 inwhich the NTSB cited crew error asplaying a central role.”

Daley, in his review, says: “While theNTSB must determine the probablecause of each specific accident, theauthors take a different approach: wouldother pilots be vulnerable to making thekinds of errors made by the accident crewand, if so, why? This original approachreveals factors that make all pilotsvulnerable to specific types of error incertain situations. In adopting thisapproach, the authors challenge theassumption that, if expert pilots makeerrors, this is evidence of their lack ofskill, vigilance, or conscientiousness.

Instead, the authors emphasize theinteractions of subtle variations in taskdemands, incomplete informationavailable to pilots, and the inherentnature of skilled performance.”

He adds, “The book will be informativefor diverse readers in the air transportindustry, including operational staff,researchers, safety analysts, accidentinvestigators, designers of systems andprocedures, training providers, andstudents….

“The main significance of this book isin its re-framing of the causes of airlineaccidents: the authors argue that, if wemust continue to conceive of airlineaccidents in terms of deficiency, then thatdeficiency should be attributed to theoverall air transport system. Such anapproach can contribute to aviationsafety by providing a foundation forimproving equipment, training, proce-dures, and organizational policy. In sodoing, it is possible to reduce thefrequency of ‘system accidents’ and todevise adequate protection against thetypes of errors to which many, if not all,pilots—as well as many other experts—are vulnerable.” ◆

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COMMITTEE CHAIRMENAudit, Dr. Michael K. Hynes

([email protected])Award, Gale E. Braden

([email protected])Ballot Certification, Tom McCarthy

([email protected])Board of Fellows, VacantBylaws, Darren T. Gaines

([email protected])Code of Ethics, Jeff Edwards

([email protected])Membership, Tom McCarthy

([email protected])Nominating, Tom McCarthy

([email protected])Reachout, James P. Stewart

([email protected])Seminar, Barbara Dunn

([email protected])

WORKING GROUP CHAIRMENAir Traffic Services, John A. Guselli (Chair)

([email protected])Ladislav Mika (Co-Chair) ([email protected])

Cabin Safety, Joann E. Matley([email protected])

Corporate Affairs, John W. Purvis([email protected])

Flight Recorder, Michael R. Poole([email protected])

General Aviation, William (Buck) Welch([email protected])

Government Air Safety, Willaim L. McNease([email protected])

Human Factors, Richard Stone([email protected])

Investigators Training & Education,Graham R. Braithwaite([email protected])

CORPORATE MEMBERSAAIU Ministry of Transport BulgariaAccident Investigation Board, FinlandAccident Investigation Board/NorwayAccident Investigation & Prevention BureauAeronautical & Maritime Research LaboratoryAeroVeritas Aviation Safety Consulting, Ltd.Aerovias De Mexico, S.A.De C.V.Air Accident Investigation Bureau of SingaporeAir Accident Investigation Unit—IrelandAir Accidents Investigation Branch—U.K.Air Canada Pilots AssociationAir Line Pilots AssociationAir New Zealand, Ltd.Airbus S.A.S.Airclaims LimitedAircraft Accident Investigation Bureau—SwitzerlandAircraft Mechanics Fraternal AssociationAircraft & Railway Accident Investigation CommissionAirservices AustraliaAirTran AirwaysAlaska AirlinesAlitalia Airlines—Flight Safety Dept.All Nippon Airways Company LimitedAllied Pilots AssociationAmerican Eagle Airlines

American Underwater Search & Survey, Ltd.AmSafe AviationAramco Associated CompanyASPA de MexicoAssociation of Professional Flight AttendantsAtlantic Southeast Airlines—Delta ConnectionAustralian Transport Safety BureauAviation Safety CouncilAvions de Transport Regional (ATR)BEA-Bureau D’Enquetes et D’AnalysesBoard of Accident Investigation—SwedenBoeing Commercial AirplanesBombardier Aerospace Regional AircraftBundesstelle fur Flugunfalluntersuchung—BFUCathay Pacific Airways LimitedCavok Group, Inc.Centurion, Inc.Charles Taylor Aviation, SingaporeChina AirlinesCirrus DesignCivil Aviation Safety Authority AustraliaColegio De Pilotos Aviadores De Mexico, A.C.Comair, Inc.Continental AirlinesContinental ExpressCOPAC/Colegio Oficial de Pilotos de la Aviacion ComercialCranfield Safety & Accident Investigation CentreCurt Lewis & Associates, LLCDCI/Branch AIRCODefence Science and Technology Organization (DSTO)Delta Air Lines, Inc.Directorate of Aircraft Accident Investigations—

NamibiaDirectorate of Flight Safety (Canadian Forces)Directorate of Flying Safety—ADFDombroff Gilmore Jaques & French P.C.Dutch Airline Pilots AssociationDutch Transport Safety BoardEL AL Israel AirlinesEmbraer-Empresa Brasileira de Aeronautica S.A.Embry-Riddle Aeronautical UniversityEmirates AirlineEra Aviation, Inc.European Aviation Safety AgencyEVA Airways CorporationExponent, Inc.Federal Aviation AdministrationFinnair OyjFinnish Military Aviation AuthorityFlight Attendant Training Institute at Melville CollegeFlight Safety FoundationFlight Safety Foundation—TaiwanFlightscape, Inc.Galaxy Scientific CorporationGeneral Aviation Manufacturers AssociationGE Transportation/Aircraft EnginesGlobal Aerospace, Inc.Gulf Flight Safety Committee, Azaiba, OmanHall & Associates, LLCHellenic Air Accident Investigation

& Aviation Safety BoardHoneywellHong Kong Airline Pilots AssociationHong Kong Civil Aviation DepartmentIFALPA

Independent Pilots AssociationInt’l Assoc. of Mach. & Aerospace WorkersInterstate Aviation CommitteeIrish Air CorpsIrish Aviation AuthorityJapan Airlines Domestic Co., LTDJapanese Aviation Insurance PoolJeppesenJetBlue AirwaysJones DayKLM Royal Dutch AirlinesKorea Air Force Safety Ctr.Korea Aviation & Railway Accident Investigation BoardKreindler & Kreindler, LLPL-3 Communications Aviation RecordersLearjet, Inc.Lockheed Martin CorporationLufthansa German AirlinesMyTravel AirwaysNational Aerospace Laboratory, NLRNational Air Traffic Controllers Assn.National Business Aviation AssociationNational Transportation Safety BoardNAV CanadaNigerian Ministry of Aviation and Accident

Investigation BureauNorthwest AirlinesParker AerospacePhoenix International, Inc.Pratt & WhitneyQantas Airways LimitedQatar AirwaysQwila Air (Pty), Ltd.Raytheon CompanyRepublic of Singapore Air ForceRolls-Royce, PLCRoyal Netherlands Air ForceRoyal New Zealand Air ForceRTI Group, LLCSandia National LaboratoriesSAS BraathensSaudi Arabian AirlinesSICOFAA/SPSSikorsky Aircraft CorporationSkyservice Airlines, Ltd.Singapore Airlines, Ltd.SNECMA MoteursSouth African AirwaysSouth African Civil Aviation AuthoritySouthern California Safety InstituteSouthwest Airlines CompanySouthwest Airlines Pilots’ AssociationStar Navigation Systems Group, Ltd.State of IsraelTransport CanadaTransportation Safety Board of CanadaU.K. Civil Aviation AuthorityUND AerospaceUniversity of NSW AviationUniversity of Southern CaliforniaVolvo Aero CorporationWestJet ◆


WHO’S WHO

WestJet Navigates the SMS Airways

ISASI107 E. Holly Ave., Suite 11Sterling, VA 20164-5405 USACHANGE SERVICE REQUESTED

NON-PROFIT ORG.U.S. POSTAGE

PAIDPermit #273

ANNAPOLIS, MD

WHO’S WHO

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(Who’s Who is a brief profile of, and pre-pared by, the represented ISASI corporatemember organization to enable a morethorough understanding of the organiza-tion’s role and functions.—Editor)

Based in Calgary, Alberta, WestJet isCanada’s original low-fare airline.WestJet took flight on Feb. 29,

1996, serving five destinations with threeBoeing 737-200 aircraft and 220 employ-ees. As of Nov. 30, 2007, WestJet hasgrown, offering scheduled and charterservice to 38 cities across North Americaand the Caribbean with a fleet of 70Boeing “next generation” 737 aircraft anda team of more than 6,700 employees.

WestJet’s fleet is the most modern andefficient in North America, featuringblended winglets on all B-737-700 and B-737-800 aircraft that minimize fuelconsumption and environmental impact.The company has plans to grow its fleet tomore than 100 aircraft by 2012.

The company has experienced expo-nential growth over its short 11½ years inoperation. Year 2006 revenue wasreported at $1.8 billion, available seatmiles at 12.5 billion, and revenue passen-ger miles at 9.8 billion. More than 10million guests (known as passengers withmost other carriers) were carried in 2006.

WestJet credits its business success inlarge part to the power of its positivecorporate culture. The work environmentis positive, with management empoweringits people to make the best decisions forthe company, its guests, and its sharehold-ers. WestJet’s people-oriented environ-ment has been a key factor in its successfulimplementation of Safety ManagementSystems (SMSs) on which it embarked in2005 under the Canadian aviation regula-tions. Throughout the last 2 years, WestJethas documented existing safety manage-ment processes, implemented new ones,and built an infrastructure to support allSMS elements. Full SMS implementationis scheduled for the autumn of 2008.

A key milestone was the deployment ofthe company safety database in April2006. Hosting more than 60 users, thesafety database supports WestJet’s SMSprocesses, which manage both proactiveand reactive safety reports in a similarmanner. Other database features includeonline safety reporting, corrective actiontracking, permanent occurrence andinvestigation logs, data analysis tools, and

reviews the report and implementscorrective actions, as required, accordingto time lines specified in the companysafety manual. Follow-up assessment ofcorrective action effectiveness is thenconducted and the entire process is closedoff by the company’s Safety ManagementCommittee, which is chaired by itsaccountable executive.

WestJet’s SMS is very specific as to theroles of the safety and leadership teams.Safety teams facilitate development,implementation, and operation of safetymanagement processes; however, thesenior leadership team retains overallresponsibility for all operational riskmanagement processes and risk controlactivities. SMS elements have beenintegrated into the company’s orientation,strategic planning, and training pro-grams. Extensive use is made of interac-tive computer-based training andelectronic documentation so that employ-ees throughout the network can accessSMS resources and apply SMS principlesin their daily activities.

With an ingrained mission to “enrichthe lives of everyone in WestJet’s worldby providing safe, friendly, and affordableair travel,” WestJet is integrating SMSthroughout the organization as it strivesto be the No. 1 choice for air travelers. ◆

scheduling of audits and repetitive tasks.Common standards for operational risk

management have been implementedacross the company. Once a hazard isidentified, it receives an initial riskclassification that drives the follow-upprocess and time line. Risk classificationsare validated by expert consensus orthrough full investigations, which arerequired for all elevated risk reports.

A typical investigative follow-up sees adepartment safety team log the occur-rence report, communicate with thereporter, assign an initial risk rating,conduct an investigation, convene a safetyreview team, and publish a report offindings and causes. Following thisprocess, a management representative

isasi forum april-june 2008€¦ · 2,000 aircraft accidents and incidents, which made his name...

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