egpws-pilotguide-revc

060-4241-000 • Rev. C - 6/99Enhanced Ground Proximity Warning System Pilot Guide 1

TABLE OF CONTENTS

SECTION 1 Introduction ...................................................................... 2

SECTION 2 System Description ............................................................ 5

SECTION 3 Operational Procedures .................................................. 44

SECTION 4 Definitions....................................................................... 56

Request for Information ...................................................................... 58

060-4241-000 • Rev. C - 6/992 Enhanced Ground Proximity Warning System Pilot Guide

This Pilot Guide describes the functions and opera-tion of the MKV and MKVII Enhanced GroundProximity Warning System (EGPWS).

The document is divided into four sections. Section1 is this introduction and the following brief de-scription of the EGPWS and its features. Section 2provides a functional description of the EGPWS.This includes descriptions of the various systemmodes, Built-In Test (BIT) and monitoring func-tions, and system features. Section 3 providesgeneral operating procedures to follow when thesystem gives a caution or warning (alert). Section4 provides definitions of terms used in this manual.

This guide does not supercede FAA approved data,Flight Manuals, individual Operations Manuals, re-quirements, or procedures. Pilots should bethoroughly familiar with their own company poli-cies, system configuration, requirements, andprocedures with respect to the operation of aircraftwith the EGPWS.

The information in this document is intended as ageneral explanation of the AlliedSignal EGPWS. Itcontains a general description of system perfor-mance assuming identified options are active, andhighlights deviations in system performance result-ing when a feature is disabled.

The EGPWS is a terrain awareness and alerting sys-tem providing terrain alerting and display functionswith additional features.

The EGPWS uses aircraft inputs including geo-graphic position, attitude, altitude, airspeed, andglideslope. These are used with internal terrain,obstacles, and airport databases to predict a poten-tial conflict between the aircraft flight path and

What is theEGPWS?

SECTION 1

Introduction


terrain or an obstacle. A terrain or obstacle conflictresults in the EGPWS providing a visual and audiocaution or warning alert.

Additionally, the EGPWS provides alerts for excessiveglideslope deviation, too low with flaps or gear notin landing configuration, and optionally providesbank angle and altitude callouts based on systemprogram pin selection. Detection of severewindshear conditions is also provided for selectedaircraft types when enabled.

The EGPWS incorporates several “enhanced” features:

• Terrain Alerting and Display (TAD) providesa graphic display of the surrounding terrain onthe Weather Radar Indicator, EFIS, or a dedicateddisplay. Based on the aircraft’s position and theinternal database, the terrain topography (withinthe display range selected) that is above or within2000 feet below the aircraft altitude is presentedon the system display. This feature is an option,enabled by program pins during installation.

• “Peaks” is a TAD supplemental feature providingadditional terrain display features for enhancedsituational awareness, independent of the aircraft’saltitude. This includes digital elevations for thehighest and lowest displayed terrain, additionalelevation (color) bands, and a unique represen-tation of 0 MSL elevation (sea level and its corre-sponding shoreline). This feature is an option,enabled by program pins during installation.

• “Obstacles” is a feature utilizing an obstacle da-tabase for obstacle conflict alerting and display.EGPWS caution and warning visual and audioalerts are provided when a conflict is detected.Additionally, when TAD is enabled, Obstacles aregraphical displayed similar to terrain. This fea-ture is an option, enabled by program pinsduring installation.


PhysicalDescription

• A process feature called Envelope Modulationutilizes the internal database to tailor EGPWSalerts at certain geographic locations to reducenuisance warnings and provide added protection.

• A Terrain Clearance Floor feature adds an addi-tional element of protection by alerting the pilot ofpossible premature descent. This is intended fornon-precision approaches and is based on the cur-rent aircraft position relative to the nearest runway.This feature is enabled with the TAD feature.

• An Aural Declutter feature reduces the repeti-tion of warning messages. This feature isoptional, and may be disabled by system programpins during installation.

• Geometric Altitude, based on GPS altitude, is acomputed pseudo-barometric altitude designedto reduce or eliminate altitude errors resultingfrom temperature extremes, non-standard pres-sure altitude conditions, and altimeter miss-sets.This ensures an optimal EGPWS alerting and dis-play capability.

Some of these features have been added to theEGPWS as the system evolved and are not present inall Enhanced Ground Proximity Warning Computer(EGPWC) part numbers. For specific effectivity, re-fer to an applicable Airplane Flight Manual (AFM) orEGPWS Airplane Flight Manual Supplement (AFMS)or contact AlliedSignal for assistance.

The EGPWC is packaged in a 2 MCU ARINC 600-6rack mounted enclosure weighing less than 8 lbs.No special vibration isolation mounting or forcedair-cooling is required.

115 VAC (400 Hz.) or 28 VDC versions of the EGPWCare available. Units are also available with an inter-nal GPS receiver for required GPS data when anotherGPS source is not available.

For more detailed descriptions and information,contact AlliedSignal.


SECTION 2

System Description

Enhanced Ground Proximity Warning System .............................. 6

EGPWS Database ................................................................................... 6

Basic Functions:

Mode 1 - Excessive Descent Rate ......................................................... 8

Mode 2 - Excessive Closure to Terrain ................................................. 9

Mode 3 - Altitude Loss After Takeoff .................................................... 12

Mode 4 - Unsafe Terrain Clearance .................................................... 13

Mode 5 - Excessive Glideslope Deviation ........................................... 18

Mode 6 - Advisory Callouts ................................................................. 20

Mode 7 - Windshear Alerting ............................................................. 24

Enhanced Functions:

Envelope Modulation.......................................................................... 26

Terrain Clearance Floor ..................................................................... 26

Terrain Look Ahead Alerting ............................................................... 27

Terrain Alerting and Display ................................................................ 29

Standard TAD ...................................................................................... 29

Peaks .................................................................................................. 32

Geometric Altitude ............................................................................... 36

Aural Message Priority ....................................................................... 37

System Inputs ................................................................................... 39

System Outputs ................................................................................. 40

Options .............................................................................................. 41


EnhancedGroundProximityWarningSystem

The EGPWS incorporates the functions of the basicGround Proximity Warning System (GPWS). Thisincludes the following alerting modes:

Additionally, Windshear alerting (Mode 7) is pro-vided for specific aircraft types. Mode 7 provideswindshear caution and/or warning alerts when anEGPWS windshear threshold is exceeded.

The EGPWS adds to these 7 basic functions the abil-ity to compare the aircraft position to an internaldatabase and provide additional alerting and dis-play capabilities for enhanced situational awarenessand safety (hence the term “Enhanced” GPWS).

The EGPWS internal database consists of four sub-sets:

1. A worldwide terrain database of varying degreesof resolution.

2. An obstacles database containing cataloged ob-stacles 100 feet or greater in height locatedwithin North America and portions of the Carib-bean (expanding as data is obtained).

3. A worldwide airport database containing infor-mation on hard-surface runways 3500 feet orlonger in length. For a specific list of the air-ports included, refer to AlliedSignal document060-4267-000 or access on the Internet atwebsite www.egpws.com.

EGPWSDatabase

MODE 1Excessive Descent Rate

“Sinkrate”“Pull Up”

MODE 6Advisory Callouts

“Bank Angle”“Minimums”

Selected Altitudes

MODE 5Excessive Deviation Below

Glideslope“Glideslope”

MODE 4Unsafe Terrain Clearance

“Too Low–Terrain”“Too Low–Gear”“Too Low–Flaps”

MODE 3Altitude Loss After Takeoff

“Terrain...Terrain”“Pull Up”

MODE 2Excessive Terrain

Closure Rate“Terrain...Terrain”

“Pull Up”


4. An Envelope Modulation database to support theEnvelope Modulation feature discussed later.

AlliedSignal is constantly striving to improve theEGPWS database in content, resolution, and accuracy.Notification of a Database update is accomplished byService Bulletin. Database updates are distributed onPCMCIA data cards and downloaded via a card slot inthe front panel of each EGPWC. Contact AlliedSignalfor additional information.

Because the overwhelming majority of “ControlledFlight Into Terrain” (CFIT) accidents occur near anairport, and the fact that aircraft operate in closeproximity to terrain near an airport, the terrain da-tabase contains higher resolution grids for airportareas. Lower resolution grids are used outside air-port areas where aircraft enroute altitude makeCFIT accidents less likely and terrain feature detailis less important to the flight crew.

With the use of accurate GPS or FMS information,the EGPWS is provided present position, track, andground speed. With this information the EGPWS isable to present a graphical plan view of the aircraftrelative to the terrain and advise the flight crew of apotential conflict with the terrain or obstacle. Con-flicts are recognized and alerts provided whenterrain violates specific computed envelope bound-aries on the projected flight path of the aircraft.Alerts are provided in the form of visual light an-nunciation of a caution or warning, audioenunciation based on the type of conflict, and colorenhanced visual display of the terrain or obstaclerelative to the forward look of the aircraft. The ter-rain display is provided on the Weather RadarIndicator, EFIS display, or a dedicated EGPWS dis-play and may or may not be displayed automatically.

The following sections provide functional descriptionsof the EGPWS basic and enhanced functions and fea-tures, and system input and output requirements.


BASIC FUNCTIONS:MODE 1

ExcessiveDescentRate

Mode 1 provides alerts for excessive descent rateswith respect to altitude AGL and is active for allphases of flight. This mode has inner and outeralert boundaries as illustrated in the diagram andgraph below.

Penetration of the outer boundary activates theEGPWS caution lights and “SINKRATE,SINKRATE” alert enunciation. Additional“SINKRATE, SINKRATE ” messages will occur foreach 20% degradation.

Penetration of the inner boundary activates theEGPWS warning lights and changes the audio mes-sage to “PULL UP” which repeats continuouslyuntil the inner warning boundary is exited.

Note: “Pull Up” may be preceded by “Whoop, Whoop” insome configurations based on the audio menu option se-lected.

If a valid ILS Glideslope front course is receivedand the aircraft is above the glideslope centerline,

Ra

dio

Alt

itu

de

(F

EE

T)

D e s c e n t R a t e ( F E E T / M I N U T E )

3000

2500

2000

1500

1000

500

0

2000 4000 6000 8000 1000

"SINKRATE"

"PULL UP!"

0

"SINKRATE"

"PULLUP"

"SINKRATE SINKRATE"

"PULL UP"


the outer (sinkrate) boundary is adjusted to desen-sitize the sinkrate alerting. This is to preventunwanted alerts when the aircraft is safely captur-ing the glideslope (or repositioning to thecenterline) from above the beam.

If the Aural Declutter feature is disabled, thesinkrate alert boundary remains fixed and the auralmessage “SINKRATE” repeats continuously untilthe outer boundary is exited.

The EGPWS offers a Steep Approach option forgiven aircraft types that desensitizes the alertboundaries to permit steeper than normal ap-proaches (e.g., MLS or GPS) without unwantedalerts.

Mode 2 provides alerts to help protect the aircraftfrom impacting the ground when rapidly rising ter-rain with respect to the aircraft is detected. Mode 2is based on Radio Altitude and on how rapidly Ra-dio Altitude is decreasing (closure rate). Mode 2exists in two forms, 2A and 2B.

Mode 2A is active during climbout, cruise, and ini-tial approach (flaps not in the landingconfiguration and the aircraft not on glideslopecenterline). If the aircraft penetrates the Mode 2Acaution envelope, the aural message “TERRAIN,TERRAIN” is generated and cockpit EGPWS cau-tion lights will illuminate. If the aircraft continuesto penetrate the envelope, the EGPWS warninglights will illuminate and the aural warning message“PULL UP” is repeated continuously until thewarning envelope is exited.

Note: “Pull Up” may be preceded by “Whoop,Whoop” in some configurations based on the audiomenu option selected.

Upon exiting the warning envelope, if terrain clear-ance continues to decrease, the aural message“TERRAIN” will be given until the terrain clear-

MODE 1

Continued

MODE 2

ExcessiveClosure toTerrain

MODE 2A


ance stops decreasing. In addition, the visual alertwill remain on until the aircraft has gained 300 feetof barometric altitude, 45 seconds has elapsed, orlanding flaps or the flap over-ride switch is activated.

The graph below shows how the upper boundary ofthe Mode 2 alert envelope varies as a function of theaircraft speed. As airspeed increases from 220knots to 310 knots, the boundary expands to pro-vide increased alert times at higher airspeeds.

MODE 2A

Continued

MODE 2B Mode 2B provides a desensitized alerting envelopeto permit normal landing approach maneuversclose to terrain without unwanted alerts. Mode 2Bis automatically selected with flaps in the landingconfiguration (landing flaps or flap over-ride se-lected) or when making an ILS approach withGlideslope and Localizer deviation less than 2 dots.


It is also active during the first 50 seconds aftertakeoff.

During an approach, if the aircraft penetrates theMode 2B envelope with either the gear or flaps noin the landing configuration, the aural message“TERRAIN, TERRAIN” is generated and theEGPWS caution lights illuminate. If the aircraftcontinues to penetrate the envelope, the EGPWSwarning lights illuminate and the aural message“PULL UP” is repeated continuously until thewarning envelope is exited. If the aircraft penetratesthe Mode 2B envelope with both gear and flaps inthe landing configuration, the aural “PULL UP”messages are suppressed and the aural message“TERRAIN” is repeated until the envelope is exited.

The graph below shows the Mode 2B envelope.

MODE 2BContinued


MODE 3

AltitudeLoss AfterTakeOff

Mode 3 provides alerts for significant altitude lossafter takeoff or low altitude go-around (less than245 feet AGL) with gear or flaps not in the landingconfiguration. The amount of altitude loss that ispermitted before an alert is given is a function ofthe height of the aircraft above the terrain as shownbelow. This protection is available until the EGPWSdetermines that the aircraft has gained sufficient al-titude that it is no longer in the takeoff phase offlight. Significant altitude loss after takeoff or dur-ing a low altitude go-around activates the EGPWScaution lights and the aural message “DON’TSINK, DON’T SINK”. The aural message is onlyenunciated twice unless altitude loss continues.Upon reestablishing a positive rate of climb, theEGPWS caution lights extinguish and the aural alertwill cease.

If the Aural Declutter feature is disabled, the warn-ing is enunciated continuously until positive climbis established.


MODE 4

UnsafeTerrainClearance

MODE 4A

Mode 4 provides alerts for insufficient terrain clear-ance with respect to phase of flight, configuration,and speed. Mode 4 exists in three forms, 4A, 4B,and 4C.

• Mode 4A is active during cruise and approachwith the gear and flaps not in the landing con-figuration.

• Mode 4B is active during cruise and approachwith the gear in the landing configuration andflaps not in the landing configuration.

• Mode 4C is active during the takeoff phase offlight with either the gear or flaps not in thelanding configuration.

Mode 4 alerts activate the EGPWS caution lights andaural messages.

To reduce nuisance alerts caused by over-flying an-other aircraft, the upper limit of the Mode 4A/Balerting curve can be reduced (from 1000) to 800feet. This occurs if the airplane is above 250 knotswith gear and flaps not in landing configurationand a sudden change in Radio Altitude is detected.This is intended to eliminate nuisance alerts whileflying a holding pattern and an aircraft over-flightoccurs (with 1000 foot separation).

Mode 4A is active during cruise and approach withgear and flaps up. This provides alerting duringcruise for inadvertent flight into terrain where ter-rain is not rising significantly, or the aircraft is notdescending excessively. It also provides alerting forprotection against an unintentional gear-up landing.

Below 1000 feet AGL and above 190 knots airspeed,the Mode 4A aural alert is “TOO LOW TERRAIN”.This alert is dependent on aircraft speed such thatthe alert threshold is ramped between 500 feet at190 knots to 1000 feet at 250 knots.


MODE 4A

Continued

MODE 4B

Below 500 feet AGL and less than 190 knots air-speed, the Mode 4A aural alert is “TOO LOWGEAR”.

For either Mode 4A alert, subsequent alert mes-sages occur only if penetration of the envelopeincreases by 20%. EGPWS caution lights extinguishand aural messages cease when the Mode 4A alertenvelope is exited.

If the Aural Declutter feature is disabled, mode 4Aalert messages are repeated continuously until theMode 4A envelope is exited.

Mode 4B is active during cruise and approach, withgear down and flaps not in the landing configuration.

Below 1000 feet AGL and above 159 knots air-speed, the Mode 4B aural alert is “TOO LOWTERRAIN”. This alert is dependent on aircraft


speed such that the alert threshold is ramped be-tween 245 feet at 159 knots to 1000 feet at 250knots.

Below 245 feet AGL and less than 159 knots air-speed, the Mode 4B aural alert is “TOO LOWFLAPS”. For turboprop and select turbofan aircraft,the “TOO LOW FLAPS” warning curve is loweredto 150 or 200 feet AGL and less than 148 knots.

If desired, the pilot may disable the “TOO LOWFLAPS” alert by engaging the Flap Override switch(if installed). This precludes or silences the Mode4B flap alert until reset by the pilot.

For either Mode 4B alert, subsequent alert messagesoccur only if penetration of the envelope increasesby 20%. EGPWS caution lights extinguish and auralmessages cease when the Mode 4B alert envelope isexited.

If the Aural Declutter feature is disabled, mode 4Balert messages are repeated continuously until theMode 4B envelope is exited.

MODE 4B

Continued


MODE 4C The Mode 4C alert is intended to prevent inadvert-ent controlled flight into the ground during takeoffclimb into terrain that produces insufficient closurerate for a Mode 2 alert. After takeoff, Mode 4A and4B provide this protection.

Mode 4C is based on an EGPWS computed Mini-mum Terrain Clearance (MTC) floor, that increaseswith Radio Altitude. It is active after takeoff whenthe gear or flaps are not in the landing configura-tion. It is also active during a low altitudego-around if the aircraft has descended below 245feet AGL.

At takeoff the Minimum Terrain Clearance (MTC) iszero feet. As the aircraft ascends the MTC is in-creased to 75% of the aircraft’s Radio Altitude(averaged over the previous 15 seconds). Thisvalue is not allowed to decrease and is limited to500 feet AGL for airspeed less than 190 knots. Be-ginning at 190 knots, the MTC increases linearly tothe limit of 1000 feet at 250 knots.

If the aircraft’s Radio Altitude decreases to the valueof the MTC, the EGPWS caution lights and the auralmessage “TOO LOW TERRAIN” are provided.

EGPWS caution lights extinguish and aural mes-sages cease when the Mode 4C alert envelope isexited.

If the Aural Declutter feature is disabled, mode 4Balert messages are repeated continuously until theMode 4B envelope is exited.


MODE 4C

Continued

Mode 5 provides two levels of alerting for when theaircraft descends below glideslope, resulting in ac-tivation of EGPWS caution lights and auralmessages.

The first level alert occurs when below 1000 feetRadio Altitude and the aircraft gets 1.3 dots orgreater below the beam. This turns on the cautionlights and is called a “soft” alert because the audiomessage “GLIDESLOPE” is enunciated at half vol-ume. 20% increases in the glideslope deviationcause additional “GLIDESLOPE” messages enunci-ated at a progressively faster rate.

ExcessiveDeviationBelowGlideslope


To avoid unwanted Below Glideslope alerts whencapturing the localizer between 500 and 1000 feetAGL, alerting is varied in the following ways:

• Below Glideslope alerts are enabled only if the lo-calizer is within 2 dots, landing gear and flapsare selected, Glideslope Cancel is not active, anda front course approach is determined.

• The upper altitude limit for the alert is modu-lated with vertical speed. For descent rates above500 FPM, the upper limit is set to the normal1000 feet AGL. For descent rates lower than 500FPM, the upper limit is desensitized (reduced) toa minimum of 500 feet AGL.

The second level alert occurs when below 300 feetRadio Altitude with 2 dots or greater glideslope de-viation. This is called a “hard” alert because alouder “GLIDESLOPE, GLIDESLOPE” message isenunciated every 3 seconds continuing until the“hard” envelope is exited. The caution lights re-main on until a glideslope deviation less than 1.3dots is achieved.

MODE 5

Continued


Additionally, both alert levels are desensitized below150 feet AGL, to allow for normal beam variationsnearer the ground, and reduce the possibility ofnuisance alerts.

If the Aural Declutter feature is disabled, messagesare repeated continuously until the Mode 5 enve-lope is exited.

Mode 5 alerts can be canceled by pressing theGlideslope Cancel switch (if installed). The EGPWSwill interpret this switch one of two ways dependingon the installation configuration.

• A standard glideslope cancel switch allows formanually canceling Mode 5 alerting any time be-low 2000 feet AGL. This is automatically resetwhen the aircraft descends below 30 feet orclimbs above 2000 feet AGL.

• An alternate glideslope cancel switch allows formanually canceling Mode 5 alerting at any timeand any altitude. The cancel is reset by againpressing the cancel switch, or automatically if gearor flaps are raised, or the aircraft is on theground. Due to the nature of the alternate cancelswitch, this method requires that there be a cock-pit annunciation that glideslope cancel is in effect.

EGPWS Mode 5 alerts are inhibited duringbackcourse approaches to prevent nuisance alertsdue to false fly up lobes from the Glideslope. TheEGPWC determines a backcourse operation ifeither: 1) the aircraft’s magnetic track is greaterthan 90 degrees from the runways approach course,or 2) a glideslope inhibit discrete is set.

MODE 5

Continued


MODE 6

AdvisoryCallouts

Mode 6 provides EGPWS advisory callouts based on themenu-selected option established at installation (set byprogram pin configuration). These callouts consist ofpredefined Radio Altitude based voice callouts ortones and an excessive bank angle warning. Thereis no visual alerting provided with these callouts.

The following is a list of each of the possible altitudecallouts or tones:CALLOUT ........................................... Occurs at (feet AGL)“RADIO ALTIMETER” ............................................................... 2500“TWENTY FIVE HUNDRED” ...................................................... 2500“FIFTEEN HUNDRED” .............................................................. 1500“ONE THOUSAND” ................................................................. 1000 a

“FIVE HUNDRED” ..................................................................... 500 a

Five Hundred Tone (2 second 960 Hz) ...................................... 500“FOUR HUNDRED” ..................................................................... 400“THREE HUNDRED” ................................................................... 300“TWO HUNDRED” ...................................................................... 200“APPROACHING MINIMUMS” ............................................... DH+80“APPROACHING DECISION HEIGHT” ................................. DH+100“PLUS HUNDRED” .............................................................. DH+100“FIFTY ABOVE” .................................................................... DH+50“MINIMUM” ................................................................................ DH“MINIMUMS” .............................................................................. DH“DECIDE” .................................................................................... DH“ONE HUNDRED” ....................................................................... 100One Hundred Tone (2 second 700 Hz) ..................................... 100“EIGHTY” ..................................................................................... 80“SIXTY” ........................................................................................ 60“FIFTY” ........................................................................................ 50“FORTY” ....................................................................................... 40“THIRTY FIVE” ............................................................................. 35Thirty Five Tone (1 second 1400 Hz) ........................................... 35“THIRTY” ..................................................................................... 30“TWENTY” .................................................................................... 20Twenty Tone (1/2 second 2800 Hz) ............................................. 20“TEN” ........................................................................................... 10“FIVE” ............................................................................................ 5“ZERO” .......................................................................................... 0

a. May be Barometric Altitude above the field elevation for some aircraft types.

In some cases a callout is stated twice (e.g., “MINI-MUMS, MINIMUMS”) but in all cases a given calloutis only enunciated once per approach.

AltitudeCallouts


Decision Height (DH) based callouts (ApproachingMinimums, Minimums, etc.) require the landinggear to be down and occur when descendingthrough the Radio Altitude corresponding to the se-lected DH. These also have priority over otheraltitude callouts when overlapping. For example, ifDH is set to 200 and both “TWO HUNDRED” and“MINIMUMS” are valid callouts, then only “MINI-MUMS” will be called out at 200 feet AGL.

DH plus based callouts (e.g., Approaching Mini-mums) are only applicable for aircraft providing aDecision Height altitude to the EGPWS. Conse-quently, not all EGPWS installations can utilize thesecallout options.

Due to the variety of altitude callout choices avail-able, it is not possible to identify every combinationin this guide. Refer to an appropriate AirplaneFlight Manual or EGPWS Airplane Flight ManualSupplement for callout identification in a specificapplication or contact AlliedSignal.

Another option that may be enabled in the installa-tion is a feature called Smart 500-Foot Callout. Thisis intended to assist pilots during a non-precisionapproach by enunciating “FIVE HUNDRED” feetindependent of the altitude callout menu selectiondiscussed above. The EGPWS determines a non-precision approach when Localizer or Glideslopeare greater than 2 dots deviation (valid or not) or aback-course approach is detected.

This feature has the distinction of adding the 500-foot callout during non-precision approaches andremoving the 500-foot callout on precision ap-proaches when part of the callout option.

Smart 500FT. Callout

MODE 6

Continued


The callout “BANK ANGLE, BANK ANGLE” advisesof an excessive roll angle. The EGPWS provides sev-eral excessive bank angle envelopes supporting AirTransport, Business, or Military aircraft types (onlyAir Transport and Business are addressed below).Bank Angle

Callout

Air Trans-port BankANgle

One envelope is defined for turbo-prop and jet businessaircraft (see graph below). Bank angles in excess of:

• ± 10° between 5 and 30 feet,

• ± 10 to 40° between 30 and 150 feet,

• ± 40 to 55° between 150 and 2450 feet,

produce the bank angle advisory (shaded area).Bank angle advisories are inhibited below 5 feet.

BusinessBank Angle

Three envelopes are defined for Air Transport air-craft. These are identified as Basic Bank Angle,Bank Angle Option 1, and Bank Angle Option 2 ad-visories.

MODE 6

Continued


The Air Transport Basic Bank Angle limits are simi-lar to the Business Aircraft Bank Angle limits exceptabove 150 feet the bank limit remains at 40 asshown below.

Bank Angle Option 1 provides bank angle advisorythresholds at 35, 40, and 45 independent of altitude.In this case, an advisory at 35 is provided and an-other is not given unless 40 is exceeded and thenagain only if 45 is exceeded. If the roll rate exceedsthe audio callout time, then the bypassed limit is notindicated. Also, when any one of the thresholds isexceeded, the bank angle must reduce below 30 forthe process to reset before additional Bank AngleAdvisories can be provided.

For example, if greater than 40 is obtained before the35 callout is complete, another callout is providedonly if 45 is obtained or the bank angle is reduced toless than 30 and then again increases to 35).

Bank Angle Option 2 provides a combination of theBasic Bank Angle and Bank angle Option 1. TheBasic Bank Angle limits are provided below 130feet, and Bank Angle Option 1 is provided above130 feet.

Any one of these three Bank Angle limits can be se-lected by program pin if the aircraft type is definedas an Air Transport aircraft.

MODE 6

Continued


MODE 7

WindshearAlerting

WindshearCaution

Mode 7 is designed to provide alerts if the aircraftencounters windshear. Two alerting envelopes pro-vide either a Windshear Caution alert or aWindshear Warning alert each with distinctive auraland visual indications to the flight crew.

EGPWS windshear is provided for certain (not all)aircraft types and is a function of certain addition-ally required input signals and enabled internaldetection algorithms. These are established duringthe initial installation and addressed in the appro-priate Airplane Flight Manual (AFM) or EGPWSAirplane Flight Manual Supplement (AFMS).

Windshear Caution alerts are given if an increasingheadwind (or decreasing tailwind) and/or a severeupdraft exceed a defined threshold. These arecharacteristic of conditions preceding an encounterwith a microburst.

A Windshear Caution results in illumination of am-ber Windshear Caution lights and the aural message“CAUTION, WINDSHEAR”. This lights remain onfor as long as the aircraft is exposed to conditionsin excess of the caution alert threshold. TheWindshear Caution envelope is illustrated in the fig-ure below.

The Windshear Caution alerting can be disabled byEGPWS program pin selection so that onlyWindshear Warning alerts are provided.


WindshearWarning

Windshear Warning alerts are given if a decreasingheadwind (or increasing tailwind) and/or a severedowndraft exceed a defined threshold. These arecharacteristic of conditions within or exiting an en-counter with a microburst.

Windshear Warning results in illumination of redWindshear Warning lights and an aural siren fol-lowed by the message “WINDSHEAR,WINDSHEAR, WINDSHEAR”. The lights remainon for as long as the aircraft is exposed to condi-tions in excess of the warning alert threshold. Theaural message will not repeat unless another sepa-rate windshear event is encountered. The thresholdis adjusted as a function of available climb perfor-mance, flight path angle, airspeeds significantlydifferent from normal approach speeds, and un-usual fluctuations in Static Air Temperature(typically associated with the leading edge of amicroburst. The Windshear Warning envelope is il-lustrated in the figure below.

Mode 7 Windshear alerting is active under the fol-lowing conditions:

• During takeoff; from rotation until an altitudeof 1500 feet AGL is reached,

• During approach; From an altitude of 1500 feetdown to 10 feet AGL,

• During a missed approach; until an altitude of1500 feet AGL is reached.

MODE 7

Continued


TerrainClearanceFloor

ENHANCED FUNCTIONS:EnvelopeModulation

Due to terrain features at or near certain specificairports around the world, normal operations haveresulted in nuisance or missed alerts at these loca-tions in the past. With the introduction of accurateposition information and a terrain and airport data-base, it is possible to identify these areas and adjustthe normal alerting process to compensate for thecondition.

An EGPWS Envelope Modulation feature providesimproved alert protection and expanded alertingmargins at identified key locations throughout theworld. This feature is automatic and requires noflight crew action.

Modes 4, 5, and 6 are expanded at certain loca-tions to provide alerting protection consistent withnormal approaches. Modes 1, 2, and 4 are desen-sitized at other locations to prevent nuisancewarnings that result from unusual terrain or ap-proach procedures. In all cases, very specificinformation is used to correlate the aircraft posi-tion and phase of flight prior to modulating theenvelopes.

The Terrain Clearance Floor (TCF) function (whenenabled) enhances the basic GPWS Modes by alert-ing the pilot of descent below a defined “TerrainClearance Floor” regardless of the aircraft configu-ration. The TCF alert is a function of the aircraft’sRadio Altitude and distance (calculated from lati-tude/longitude position) relative to the center ofthe nearest runway in the database (all hard sur-face runways greater than 3500 feet in length).The TCF envelope is defined for all runways as il-lustrated below and extends to infinity, or until itmeets the envelope of another runway. The enve-lope bias factor is typically 1/2 to 2 nm and varies asa function of position accuracy.


TCF alerts result in illumination of the EGPWS cau-tion lights and the aural message “TOO LOWTERRAIN”. The audio message is provided oncewhen initial envelope penetration occurs and againonly for additional 20% decreases in Radio Altitude.The EGPWS caution lights will remain on until theTCF envelope is exited.

Another enhancement provided by the internal ter-rain database, is the ability to look ahead of theaircraft and detect terrain or obstacle conflicts withgreater alerting time. This is accomplished (whenenabled) based on aircraft position, flight pathangle, track, and speed relative to the terrain data-base image forward the aircraft.

Through sophisticated look ahead algorithms, bothcaution and warning alerts are generated if terrainor an obstacle conflict with “ribbons” projected for-ward of the aircraft (see following illustration).These ribbons project down, forward, then up fromthe aircraft with a width starting at º nm and extend-ing out at 3 laterally, more if turning. Thelook-down and up angles are a function of the air-craft flight path angle, and the look-down distance afunction of the aircraft’s altitude with respect to the

TerrainLook AheadAlerting

1/2 Runway Length

(Minimum Elevation Number)

Envelope Bias Factor

TCF Alert Envelope

12NM4NM

15NM

700'

30'

400'


nearest runway. This relationship prevents undes-ired alerts when taking off or landing. Thelook-ahead distance is a function of the aircraft’sspeed, and distance to the nearest runway.

CAUTION

WARN

A terrain conflict intruding into the caution ribbonactivates EGPWS caution lights and the aural mes-sage “CAUTION TERRAIN, CAUTION TERRAIN”or “TERRAIN AHEAD, TERRAIN AHEAD”. Anobstacle conflict provides a “CAUTION OB-STACLE, CAUTION OBSTACLE” or “OBSTACLEAHEAD, OBSTACLE AHEAD” message. The cau-tion alert is given typically 60 seconds ahead of theterrain/obstacle conflict and is repeated every sevenseconds as long as the conflict remains within thecaution area. When the warning ribbon is intruded(typically 30 seconds prior to the terrain/obstacleconflict), EGPWS warning lights activate and the au-ral message “TERRAIN, TERRAIN, PULL UP” or“OBSTACLE, OBSTACLE, PULL UP” is enunciatedwith “PULL UP” repeating continuously while theconflict is within the warning area.

The specific aural message provided is establishedduring the initial installation of the EGPWS and is afunction of whether or not the terrain and obstaclesfeatures are enabled and the selected audio menu(via program pin selection).

Refer to an applicable AFM or EGPWS AFMS for spe-cific application information or contact AlliedSignalfor additional information.


TerrainAlertingand Display

StandardTad

When a compatible Weather Radar, EFIS, or other dis-play is available and enabled, the EGPWS TerrainAlerting and Display (TAD) feature provides animage of the surrounding terrain represented invarious colors and intensities.

There are actually two types of TAD displays depend-ing on the options selected. The first provides aterrain image only when the aircraft is 2000 feet orless above the terrain (“standard”). A second fea-ture called “Peaks” enhances the standard displaycharacteristics to provide a higher degree of terrainawareness independent of the aircraft’s altitude. Ineither case, terrain and obstacles (if enabled) for-ward of the aircraft is displayed. Obstacles arepresented on the cockpit display as terrain, employ-ing the same display-coloring scheme. Peaks andObstacle functions are enabled by EGPWS programpin selection.

NOTE: With respect to standard or Peaks display,terrain and or obstacle presentation is always basedon (and scaled for) the geographic area available fordisplay. Consequently, terrain and/or obstacles out-side of the selected display range and defined displaysweep do not have any effect on the displayed image.

Standard TAD provides a graphical plan-view imageof the surrounding terrain as varying density patternsof green, yellow, and red as illustrated in the follow-ing graphics. The selected display range is alsoindicated on the display, and an indication that TAD isactive is either indicated on the display (e.g., “TERR”)or by an adjacent indicator.

TERRAIN IS SHOWNIN SHADES OF GREEN,YELLOW AND RED


Each specific color and intensity represents terrain(and obstacles) below, at, or above the aircraft’s alti-tude based on the aircraft’s position with respect tothe terrain in the database. If no terrain data isavailable in the terrain database, then this area isdisplayed in a low-density magenta color. Terrainmore than 2000 feet below the aircraft, or within400 (vertical) feet of the nearest runway elevation,is not displayed (black).

When a caution alert is triggered, the terrain (or ob-stacle) that created the alert is changed to solidyellow (100% density) as illustrated below.

Caution Terrain issolid Yellow

60 Seconds fromprojected impact

“Caution Terrain!”

+2000'

+1000'

-1000'

-2000'

0

(Variable)

Aircraft Elevation

-500’

50% Red

50% Yellow

25% Yellow

50% Green

16% Green

Black


TAD "Pop-Up"and “Auto-Range”

When a warning alert is triggered, the terrain (orobstacle) that created the alert is changed to solidred (100% density) as illustrated below.

NOTE: When a TAD caution or warning alert is ac-tive, the display image (cells) surrounding the targetare enlarged (surrounding cells are illuminated).This allows a smaller terrain or obstacle (e.g., asingle tower) to be better seen on the display.

The transition between green and yellow is belowthe aircraft in order to account for altimetry and/orterrain/obstacle height errors. Also, the transitionaltitudes between colors are biased upward propor-tional to the descent rate when greater than 1000feet per minute. This provides approximately a 30-second advance display of terrain.

Essentially, pilots should note that any yellow or redpainted terrain is at or above the aircraft’s altitudeand appropriate terrain clearance needs to be pro-vided.

Based on the display system used, there may be ad-ditional terrain display features. These are definedas installation options and allow for:

• Automatic display of terrain on the cockpit dis-play (“TAD pop-up”) in the event that a cautionor warning alert is triggered as described in Ter-

Warning Terrainis Solid Red

30 Seconds fromprojected impact

“Terrain, Terrain,–Pull Up!”


“PEAKS”

rain Look Ahead Alerting. In some cases, an ac-tive display mode must be selected first.

• “Auto-range” when Pop-up occurs. This providesfor the automatic range presentation for terrainas defined for the display system configuration(typically 10 nm). In this case, if the terrainauto-range is different than the display systemselected range, the displayed range value on thecockpit display is flashed or changed color untilthe range is manually reselected or terrain dis-play is deselected.

“Peaks” has all the characteristics of the standardTAD but with additional terrain display features forenhanced situational awareness independent of theaircraft’s altitude. The principle additions are:

• The digital display of the highest and lowest ter-rain/obstacle elevations currently displayed,

• The display of additional solid or lower densitycolor bands, including the addition of thegraphic representation of sea level (0 feet MSL).

With Terrain Display selected on, digital values rep-resenting the highest terrain/obstacle elevation andthe elevation for the bottom of the lowest colorband are displayed. These are based on the rangeselected (terrain in view)

The location of the digital values can vary somewhatfor the display used, but for this guide will beshown in the lower right corner of the display.These elevations are expressed in hundreds of feetabove sea level (e.g., 125 is 12,500 feet MSL) withthe highest elevation on top and the lowest on thebottom. However, in the event that there is no ap-preciable difference in the terrain/obstacleelevations (flat terrain), only the highest value isdisplayed. Additionally, the color of the elevationvalue is presented the same as the color of the ter-rain display containing that elevation (i.e., red if the


terrain/obstacle with that elevation is depicted asred in the terrain plan view, yellow if yellow, etc.).

When the aircraft is 500 feet (250 with gear down)or less above the terrain in view (yellow or red isdisplayed), the Peaks color scheme is identical tothe standard display, with the exception of the addi-tion of sea level when supported by the display.

Note: some displays do not support cyan (blue) and willnot display sea level in this case.

The following illustrate the Peaks display at a lowrelative altitude.

50% Red

50% Yellow

25% Yellow

16% Green

Ref Altitude + 2000

Ref Altitude + 1000

Ref Altitude -250/500

(Maximum Elevation Number)

ReferenceAltitude

Black

CyanSea Level

50% GreenRef Altitude -1000

Ref Altitude -2000(Minimum Elevation Number)

Reference Altitude is projected down from actual aircraft altitude to provide a 30 second advancedisplay of terrain when descending more than 1000 FPM.

Terrain is not shown if it is below the lowest band and/or is within 400 feet of the runwayelevation nearest the aircraft. Sea level water is displayed if supported by the display.


The following illustrate the Peaks display at a highrelative altitude.


When the aircraft is greater than 500 feet (250 withgear down) above the terrain in view (no yellow orred displayed), additional (green) color bands arepresented. These added bands are computed anddisplayed as a function of the highest and lowest el-evations in view.

The following table indicates the TAD colors and el-evations (standard and Peaks).

Color Indication

Solid Red Terrain/Obstacle Threat Area – Warning.

Solid Yellow Terrain/Obstacle Threat Area – Caution.

50% Red Dots Terrain/Obstacle that is more than 2000 feetabove aircraft altitude.

50% Yellow Dots Terrain/Obstacle that is between 1000 and 2000feet above aircraft altitude.

25% Yellow Dots Terrain/Obstacle that is 500 (250 with geardown) feet below to 1000 feet above aircraft altitude.

Solid Green Shown only when no Red or Yellow terrain(Peaks only) /Obstacle areas are within range on the display.

Highest terrain/Obstacle not within 500 (250with gear down) feet of aircraft altitude.

50% Green Dots Terrain/Obstacle that is 500 (250 with geardown) feet below to 1000 below aircraft altitude.

(Peaks only) Terrain/Obstacle that is the middle elevationband when there is no Red or Yellow terrain areaswithin range on the display.

16% Green Dots Terrain/Obstacle that is 1000 to 2000 feet belowaircraft altitude.

(Peaks only) Terrain/Obstacle that is the lower elevation bandwhen there is no Red or Yellow terrain areaswithin range on the display.

Black No significant terrain/Obstacle.

16% Cyan Water at sea level elevation (0 feet MSL).(Peaks only)

Magenta Dots Unknown terrain. No terrain data in the data-base for the magenta area shown.


TCF/TADINOP andINHIBIT

GoemetricAltitude

The EGPWS TCF and TAD functions are availablewhen all required data is present and acceptable.Aircraft position and numerous other parametersare monitored and verified for adequacy in order toperform these functions. If determined invalid orunavailable, the system will display Terrain inopera-tive or unavailable annunciations and discontinuethe terrain display if active.

TAD/TCF functions may be inhibited by manual se-lection of a cockpit Terrain Inhibit switch. Neitherloss nor inhibited TAD/TCF effects the basic GPWSfunctions (modes 1-7).

If Peaks is not active and TAD becomes unavailabledue to position error, terrain inoperative or unavail-able is not indicated if the aircraft is greater than8000 feet above the highest terrain or obsticlewithin a 320nm radius. If indicated below the 8000-foot threshold, it is extinguished when the aircraftclimbs above, and is again displayed once the air-craft descends below the 8000-foot threshold. Thiseliminates potentially longterm illumination of thecondition during the high enroute phase of flight.

Based on GPS altitude, geometric altitude is a com-puted pseudo-barometric altitude designed toreduce or eliminate errors potentially induced inCorrected Barometric Altitude by temperature ex-tremes, non-standard pressure altitude conditions,and altimeter miss-sets. This ensures an optimalEGPWS Terrain Alerting and Display capability. Geo-metric Altitude also allows EGPWS operations in QFEenvironments without custom inputs or special op-erational proceedures.

Geometric Altitude requires a MSL based GPS Alti-tude input with its associated Vertical Figure OfMerit (VFOM) and Receiver Autonomous IntegrityMonitoring (RAIM) failure indication, standard (un-corrected) altitude, Radio Altitude, Ground Speed, RollAngle, and aircraft position (Latitude and Long-itude).


Additionally, corrected Barometric Altitude, Static AirTemperature (SAT), GPS mode, and the number ofsatellites tracked are used if available.

The Geometric Altitude is computed by blending acalculated Non-Standard Altitude, Runway CalibratedAltitude (determined during takeoff), GPS CalibratedAltitude, Radio Altitude Calibrated Altitude (deter-mined during approach), and Barometric Altitude(if available). Estimates of the VFOM for each ofthese are determined and applied in order to deter-mine its weight in the final altitude. The blendingalgorithm gives the most weight to altitudes with ahigher estimated accuracy, reducing the effect of lessaccurate altitudes. Each component altitude is alsochecked for reasonableness using a window monitorcomputed from GPS Altitude and its VFOM. Altitudesthat are invalid, not available, or fall outside the rea-sonableness window are not included in the finalGeometric Altitude value.

The Geometric Altitude algorithm is designed to al-low continued operation when one or more of thealtitude components are not available. If all compo-nent altitudes are invalid or unreasonable, the GPSAltitude is used directly. If GPS Altitude fails or isnot present, then the EGPWS reverts to using Cor-rected Barometric Altitude alone.

The Geometric Altitude function is fully automaticand requires no pilot action other than the propersetting of Corrected Barometric Altitude on the Al-timeter.

Two or more messages may be activated simultan-eously, so a message priority has been established.The following table reflects the priority for thesemessage callouts. Messages at the top of the list willstart before or immediately override a lower prioritymessage even if it is already in progress.

AuralMessagePriority


MESSAGE ................................................. MODE“Windshear, Windshear, Windshear” d, j ........................................................................ 7

“Pull Up” h, i, k ........................................................................................................................... 1, 2, TA

“Terrain, Terrain” ...................................................................... 2, TA

“Obstacle, Obstacle” c .................................................................................................................. TA

“Terrain” ........................................................................................ 2

“Minimums” a, c ...................................................................................................................................... 6

“Caution Terrain, Caution Terrain” c, f .......................................................................... TA

“Caution Obstacle, Caution Obstacle” c, g ................................................................... TA

“Too Low Terrain” .................................................................. 4, TCF

Altitude Callouts c .................................................................................................................................. 6

“Speed Brake, Speed Brake” c ........................................................ 6

“Too Low Gear” ............................................................................ 4A

“Too Low Flaps” ........................................................................... 4B

“Sink Rate, Sink Rate” .................................................................... 1

“Don’t Sink, Don’t Sink” ................................................................ 3

“Glideslope” ................................................................................... 5

“Approaching Minimums” b, c................................................................................................... 6

“Bank Angle, Bank Angle” c ....................................................................................................... 6

“Caution Windshear” c, d, e ............................................................................................................ 7

“Autopilot” c .................................................................................... 6

“Flaps, Flaps” c ............................................................................... 6

Notes:

a) May also be “Minimums, Minimums” or “Decide”.

b) May also be “Approaching Decision Height”, “Fifty Above”, “PlusHundred”.

c) Message is dependent on aircraft type or option selected.

d) Windshear detection alerts provided for some aircraft types.

e) Caution alert if not disabled.

f) May also be “Terrain Ahead, Terrain Ahead”.

g) May also be “Obstacle Ahead, Obstacle Ahead”

h) May also be “Terrain Ahead Pull Up”

i) May also be “Obstacle Ahead Pull Up”

j) May be preceded by siren.

k) May be proceded by “Whoop, Whoop”

TA=Terrain Look-Ahead Alert

TCF=Terrain Clearance Floor

AuralMessagePriorityContinued


Air Data

The EGPWS uses various input signals from otheron-board systems. THe full compliment of theseother systems is dependent on the EGPWS configu-ration and options selected. Systems providingAltitude, Airspeed, Attitude, Glideslope, and posi-tion are required for basic and enhanced functions.Accelerations, Angle-of-Attack (AOA), and Flap posi-tion is required for Windshear. Inputs are alsorequired for discrete signal and control input.

The EGPWS utilizes signals from the following systems:

Uncorrected and corrected Barometric Altitude, Altituderate, Computed Airspeed, True Airspeed, and Static AirTemperature are provided by Air Data system.

Radio Altitude is provided by a Radio Altimeter sys-tem. Decision Height or Decision Height Altitude isprovided by a Radio Altimeter system or ancillarysystem.

Pitch and Roll Attitude, Latitude and Longitude Po-sition, Body Normal and Longitudinal Accelerations,Magnetic and True Track Angles, Magnetic and TrueHeading, Inertial Altitude, Groundspeed, and mode.

Latitude and Longitude Position, True Track Angle,

RadioAltitude

FMS, IRS,AHRS, Accel-erometer

FLIGHT DECKSPEAKERS AND

INTERPHONE

ALERT LAMPSOR EFISDISPLAY

EFIS NAV.DISPLAY OR Wx

RADARINDICATOR

AUDIO ALERTMESSAGES

VISUAL ALERTMESSAGES

TERRAIN DISPLAYDATA

AIRCRAFTPARAMETERSAIRCRAFT

SENSORSAND

SYSTEMS

EGPWC

GPWSALGORITHMS

AURALCALLOUTS

TERRAINAWARENESS &

OBSTACLEALERTING AND

DISPLAYALGORITHMS

TERRAINCLEARANCE

FLOORALGORITHMS

WINDSHEARDETECTION

AND ALERTINGALGORITHMS

INPUT

PROCESSING

OUTPUT

PROCESSING

CONTROL/DISCRETS

INPUTS

SystemInputs


GlobalPositioningSystem (GPS)

SystemOutputs

GPS Altitude, Groundspeed, Horizontal and VerticalFigure of Merit (VFOM/HFOM), Horizontal and Ver-tical Dilution of Precision (HDOP/VDOP),Horizontal Integrity Limit (HIL), and sensor status.

Glideslope, Localizer, ILS Tuned, Selected RunwayHeading.

Display range, and if available the Hazard Bus froma Predictive Windshear System (PWS). If EFIS, theEFIS display mode is used in some configurations.

AOA, Stick Shaker Margin.

Discrete inputs are used for system configuration,signal/status input, and control input functions.

EGPWS program pins are utilized to tell the systemthe type of aircraft and interface that it is in. Theseare defined and established during the EGPWS in-stallation. EGPWS output functions areconsequently the result of the program pin stateread each time the EGPWS is powered on.

Signal/status discretes include signals such as Deci-sion Height, Landing Flaps selected or Flap Positiondiscretes, Landing Gear selected, Terrain DisplayRange, and status discretes such as GlideslopeValid, Localizer Valid, Radio Altitude Valid associ-ated with analog signal inputs.

Control discretes control EGPWS functions. Theseinclude EGPWS Test, Glideslope Cancel, GlideslopeInhibit or Glideslope Backcourse, Terrain (display)select, Terrain Inhibit, Flap Over-ride, Audio Inhibit,Altitude Callout Enable, Steep Approach Enable,and ILS Tuned discretes.

The EGPWS provides both audio and visual outputs.

Audio outputs are provided as specific alert phrases,and altitude callouts or tones provided by anEGPWS speaker and via the cockpit Interphone sys-

VHF NavReciever

Terrain Dis-play System

Discretes

AOA Vane orStall Warning


tem for headset usage. Several audio output levelsare available, established during the installation ofthe EGPWS. These EGPWS audio outputs can be in-hibited by other systems having higher priority (i.e.,windshear) or cockpit switches in some cases. TheEGPWS also has the ability to inhibit other systemaudio such as TCAS.

Visual outputs provide discrete alert and status an-nunciations, and display terrain video when acompatible display system is available and enabled.The discrete visual alerts coincide with audio cau-tion and warning alerts to achieve an optimumterrain alerting capability. Status annunciationsprovide information to the flight crew about the sta-tus of the EGPWS (e.g., GPWS INOP) or activation ofselected functions. Terrain video is generated bythe EGPWC based on the aircraft’s current positionrelative to the surrounding terrain. This video ispresented to a Weather Radar indicator, EFIS dis-play, or a dedicated display unit.

The EGPWC uses program pin discrete inputs to de-fine the installation configuration and optionselection. The EGPWS has been designed for maxi-mum flexibility while being tailored to specificaircraft equipment, sensors, and displays. The fol-lowing list summarizes available Operator options(excluding sensor and equipment configuration op-tions):

• Flashing Lamps – when selected causes alertannunciators to flash when active.

• TAD and TCF Disable – Suppresses all TADand TCF alerting and display functions.

• Altitude Callouts – Selects desired altitudecallouts from a menu of options.

• Audio Output Level – Selects desired audiooutput level High, Medium, or Low.

• Alternate Mode 6 Volume – Selected reduces

Options


Mode 6 volume (an additional) 3 dB.

• Obstacle Awareness Enabled – Enables ob-stacle alerting and display.

• TAD Alternate Pop Up – If TRUE, disables au-tomatic terrain display when TAD or Obstaclealert is active.

• Mode 6 Volume Reduction – Selected reducesMode 6 volume 6 dB.

• Smart Callout Enable – Enables the 500-footsmart callout. “Five Hundred” is called out at500 feet Radio Altitude during non-precision ap-proaches (if 500’ is part of the altitude calloutoption selected, this callout is not given on preci-sion approaches).

• Bank Angle Enable – Enables Bank Angle alerts.

• Windshear Caution Voice Disable – DisablesWindshear Caution voice alerts providing visualalerts only.

• Audio Declutter Disable – Disables the AudioDeclutter function so that audio alerts are constant.

• Audio Alerting Voice Select – Selects thetype(s) of voice that are used for audio alerts.

• Lamp Format – One of two lamp formats areavailable.

• Lamp Format 1 provides only Mode 5“Glideslope” alerts to the caution (amber)lamp output and all other alerts (exceptWindshear and Mode 6 callouts) to the warn-ing (red) lamp output.

• Lamp Format 2 provides all “Pull Up” warningalerts to the warning (red) lamp output andall caution alerts to the caution (amber) lampoutput (Recommended).

NOTE: Windshear annunciations are provided byseparate outputs and indications and is not affectedby lamp format. Mode 6 advisories do not effect any


annunciation and are not affected by lamp format.

• Peaks Enable – Enables the display of Peaks whena Peaks capable display system is configured.

Additional input discretes are used to control or de-fine EGPWS operations:

• EGPWS Self-Test – Cockpit switch initiatesEGPWS Self-Test on the ground. Typically part ofEGPWS warning (red) lamp.

• Glideslope Cancel – Cockpit switch cancelsMode 5 Glideslope alerting. Typically part ofEGPWS caution (amber) lamp.

• Glideslope Inhibit – Inhibits Mode 5 Glideslopealerting. Normally used for backcourse approaches.

• Altitude Callout Enable – Enables Mode 6 Callouts.

• Mode 6 Low Volume – Reduces Mode 6 vol-ume (an additional) 6 dB. This is typicallyhardwired or connected to an external switch.

• TAD and TCF Inhibit – Cockpit switch to dis-able all TAD and TCF functions.

• Audio Inhibit – disables all EGPWS audio outputs.

• Steep Approach Enable – Enables Steep Approach(Mode 1 Excessive Descent Rate) alerts biasing.

• Steep Approach Select – Selects (activates)Steep Approach (Mode 1 Excessive DescentRate) alerts biasing to reduce nuisance alerts.

• Flap Over-Ride – Cockpit switch to select landingflaps when not in the landing flap configuration.

• PLI Select/Deselect – Used for displaying ordeselecting the display of EGPWS derived PitchLimit Indicator (PLI) signals when a Windshearwarning occurs.

For additional options information, refer to an ap-propriate Interface Control Document (ICD) orcontact AlliedSignal.


SECTION 3

Operational Procedures

System Constraints .............................................................................. 45

System Activation ................................................................................ 46

EGPWS Self Test ................................................................................... 47

Normal Procedures ............................................................................ 50

Caution Alerts ................................................................................ 51

Warning Alerts ............................................................................... 51

Glideslope Alerts ........................................................................... 51

Advisory Callouts ............................................................................ 52

Windshear Caution ......................................................................... 52

Windshear Warning ........................................................................ 52

Abnormal Procedures ......................................................................... 53

Emergency Procedures ....................................................................... 55


SystemConstraints

System constraints for the EGPWS are:

• If terrain data is unavailable for a particular area,then Terrain and Obstacle alerting and display isnot available for that area and the affected dis-play area is colored MAGENTA.

• The display of terrain and obstacle information isintended to serve as a situational awareness tool.It does not provide the accuracy and/or fidelity tobe the sole source for deciding terrain or ob-stacle avoidance. Navigation must not bepredicated upon the use of the EGPWS terrain/Obstacle display.

• If there is no source of aircraft position datameeting the accuracy requirements for the TADand TCF functions, then these enhanced func-tions are automatically inhibited with a resultantTerrain inoperative or unavailable indication.

• TAD/TCF functions should be manually inhibitedwhen operating within 15 nm of an airport that isnot in the airport database to avoid unwanted alerts.

• TAD/TCF functions should be manually inhibitedduring QFE operations if GPS data is unavailableor inoperative.

• TAD/TCF functions should be manually inhibitedfor ditching or other off-airport landings.

• When the TAD/TCF functions are inhibited andthe EGPWS is otherwise functional, the EGPWSreverts to providing basic GPWS functions(Modes 1 to 6 and Windshear). In this state, theEGPWS may give little or no advance warningtime for flight into precipitous terrain wherethere are few or no preceding obstructions. Thisparticularly applies if:

• The aircraft is in the landing configuration,

• The aircraft is in a stabilized descent at a normal approach descent rate,

• There is no ILS GLideslope signal beingrecieved by the EGPWS (not tuned, not available,


SystemActivation

or inoperative)

• Terrain clearance or descent rates that are notcompatible with required minimum regulatorystandards for Ground Proximity Warning equip-ment may cause unwanted alters.

• If enabled, the EGPWS uses onboard measure-ment of air mass parameters and aircraftacceleration for detection of windshear. This is areactive system and cannot predict windshear,which may be ahead of the aircraft.

• The EGPWS terrain/obstical database includescataloged human-made obstructions 100 feethigh or greater within North America and por-tions of the Caribbean (expanding). Thedatabase is not all-inclusive and newer, smaller,or unknown obstructions could be encountered.

Refer to an appropriate AFM or EGPWS AFMS forspecific system limitations and procedures.

The EGPWS is fully active when the following sys-tems are powered and functioning normally:

• EGPWS

• Radio Altimeter

• Air Data

• ILS or Glideslope Receiver

• IRS, AHRS, VG (attitude)

• GPS, FMS, or IRS (position)

• Landing gear

• Landing flaps

• Stall warning or AOA (windshear only)

• Weather Radar, EFIS, or a dedicated terrain dis-play (if terrain/obstacle display enabled)

In the event that required data for a particular func-tion is not available, then that function is auto-matically inhibited and annunciated (e.g. if positiondata is not available or determined unacceptable,


TAD and TCF is inhibited, any active terrain display isremoved, and “TERR INOP”, “TERR UNAVAIL” (orequivalent) is indicated).

Some installations utilize redundant systems so thatif the primary source of data fails, the EGPWS con-tinues on the secondary source.

EGPWS status annunciations are provided for GPWSinoperative (mode 1-6 functions), Terrain inoperative(TAD/TCF functions), and windshear inoperative.

Refer to an appropriate AFM or EGPWS AFMS forspecific system and status requirements.

The EGPWS provides a Self-Test capability for verifyingand indicating intended functions. This Self-Test ca-pability consists of six levels to aid in testing andtroubleshooting the EGPWS. These six levels are:

Level 1 –Go / No Go Test provides an overview ofthe current operational functions and anindication of their status.

Level 2 –Current Faults provides a list of the inter-nal and external faults currently detectedby the EGPWC.

Level 3 –EGPWS Configuration indicates the cur-rent configuration by listing the EGPWShardware, software, databases, and pro-gram pin inputs detected by the EGPWC.

Level 4 - Fault History provides an historicalrecord of the internal and external faultsdetected by the EGPWC.

Level 5 - Warning History provides an historicalrecord of the alerts given by the EGPWS.

Level 6 - Discrete Test provides audible indicationof any change to a discrete input state.

A level 1 Go/No Go Test is normally performed byflight crews as part of preflight checks. All levels aretypically used for installation checkout and mainte-nance operations.

EGPWSSelf-Test


A level 1 Test is used to verify proper operation of theEGPWS on the ground as follows:

1. Ensure that adequate aircraft power is available andthe EGPWS and associated systems are powered.

2. Ensure that any EGPWS inhibiting switches are inthe normal (non-inhibiting) position.

3. Verify that EGPWS inoperative annunciations areextinguished. If an inoperative annunciation isindicated, perform the following EGPWS Self-Test(below) and then seek corrective action if the in-operative condition persists.

4. If a terrain display is enabled, select terrain to bedisplayed.

5. Momentarily depress the EGPWS Self-Test switch.

When a Self-Test is initiated, the EGPWC first checksfor any configuration (installation or database) er-rors. If any are detected it is audibly enunciatedand the test is terminated. If none detected, the testcontinues through a sequence resulting in turningon and off all system annunciators, enunciating spe-cific audio messages, and if enabled, displaying avideo test pattern on the terrain display (see illustra-tion below). Any functions determined inoperativeare also enunciated (e.g., “GLIDESLOPE INOP”). TheSelf-Test terminates automatically at its conclusion.

The following is a description of the expected re-sults of a typical level 1 Self-Test. Actualannunciation nomenclature and sequence may dif-fer depending on the installation.

• GPWS INOP, W/S INOP, and TERR INOP annun-ciators turn on.

• Amber caution (“BELOW G/S” or “GPWS”) an-nunciators turn on.

• “GLIDESLOPE” is announced over speaker.

• Amber annunciators turn off.

• G/S CANCEL annunciators turn on (if installed).


• G/S CANCEL annunciators turn off.

• Red warning (“PULL UP” or “GPWS”) annuncia-tors turn on.

• “PULL UP” is announced over speaker.

• Red warning annunciators turn off.

• Red Windshear warning annunciators turn on.

• (Siren) “WINDSHEAR, WINDSHEAR,WINDSHEAR” is announced over speaker.

• Red Windshear warning annunciators turn off.

• Amber Windshear caution annunciators turn on(if installed and enabled).

• Amber Windshear caution annunciators turn off.

• Red warning (“PULL UP” or “GPWS”) annuncia-tors turn on.

• “TERRAIN, TERRAIN, PULL UP” is announcedover speaker.

• Terrain test pattern is displayed (see below).

• Red warning annunciators turn off.

• GPWS INOP, W/S INOP, and TERR INOP annun-ciators turn off.

• Terrain test pattern is turned off.

6. Verify expected indications and enunciationsduring test, repeating as necessary noting any er-roneous conditions.

A successful test is accomplished if all expected in-dications are observed and no inoperative functionsor display anomalies are indicated or observed.


For more specific information, refer to an appli-cable AFM or EGPWS AFMS, or contact AlliedSignal.

The EGPWS provides visual and/or audio alerts fordetected:

• potentially dangerous terrain conditions (modes1 – 4, TCF, TAD),

• below glideslope conditions (mode 5),

• descent below predefined altitudes or excessivebank angle (mode 6),

• severe windshear conditions (mode 7)

These consist of warning, cautionary, and advisoryalerts based on the detection alert threshold pen-etration. The following list identifies the variousalerts by type and mode:

ALERT WARN CAUT. ADV.

(SIREN) “WINDSHEAR (3x)” 7

Any “PULL UP” 1,2,TA

“CAUTION WINDSHEAR” 7

“TERRAIN, TERRAIN” 2, TA

“OBSTACLE, OBSTACLE” TA

“TERRAIN” 2

“APPROACHING MINIMUMS” 6

“MINIMUMS” 6

“CAUTION TERRAIN” TA

“CAUTION OBSTACLE” TA

“TOO LOW TERRAIN” 4, TCF

“TOO LOW GEAR or FLAPS” 4

Altitude callouts 6

“SINK RATE” 1

“DON’T SINK” 3

“GLIDESLOPE” 5

“BANK ANGLE” 6

NOTE: Visual and audio indications may vary and proceduresprovided are representative. Refer to an applicable AFM or EGPWSAFMS for specific implementation.

NormalProcedures


Recommended response to EGPWS alerts are as follows:

1. Stop any descent and climb as necessary toeliminate the alert. Analyze all available instru-ments and information to determine best courseof action.

2. Advise ATC of situation as necessary.

1. Aggressively position throttles for maximumrated thrust. Apply maximum available power asdetermined by emergency need. The pilot notflying (if applicable) should set power and en-sure that TO/GA power and modes are set.

2. If engaged, disengage the autopilot and smoothlybut aggressively increase pitch toward “stickshaker” or Pitch Limit Indicators (PLI) to obtainmaximum climb performance.

3. Continue climbing until the warning is eliminatedand safe flight is assured.

4. Advise ATC of situation.

NOTE: Only vertical maneuvering is recommendedunless operating in visual conditions and/or pilotdetermines, based on all available information,that turning in addition to the climbing is the safestcourse of action. Follow established operatingprocedures.

NOTE: Navigation must not be based solely onthe use of the Terrain Awareness and AlertingDisplay (TAD).

Below Glideslope alerts consist of “soft” and“hard” alerts based on the degree of glideslopedeviation and altitude. Respond to these alerts asnecessary to correct the aircraft’s flightpath backto the Glideslope centerline or perform a missedapproach.

CautionAlerts

WarningAlerts

GlidescopeAlerts


Advisory callouts being advisory in nature are usedto announce an event or condition (e.g., “Mini-mums”). Response to these callouts should be inaccordance with standard operating procedures.

This alert generally occurs due to increasing perfor-mance windshearing conditions (i.e., increasingheadwind, decreasing tailwind, and/or updraft).This alert is generally considered advisory in thatthe crew response is to be alert to the possibility ofsubsequent significant airspeed loss and down draftconditions. Coupled with other weather factors, theWindshear Caution should be considered in deter-mining the advisability of performing a go-around.

Wind and gust allowances should be added to theapproach speed, increasing thrust if necessary. Itmay be necessary to disengage autopilot or auto-throttle. Avoid getting low on the approachglidepath or reducing the throttles to idle.

When a Windshear warning occurs, the followingprocedures should be followed:

1. Immediately initiate the Windshear escape ma-neuver in accordance with establishedWindshear procedures.

2. Aggressively apply maximum rated thrust, disen-gage autopilot and/or auto-throttle if necessary.

3. Rotate smoothly to the go-around/take-off pitchattitude, allowing airspeed to decrease if neces-sary. Maintain wings level. Do not retract flapsor landing gear.

4. If the aircraft continues to descend, increasepitch attitude smoothly and in small increments,bleeding air speed as necessary to stop descent.Use Stall Warning onset (stick shaker) as the up-per limit of pitch attitude.

5. Maintain escape attitude and thrust and delay re-tracting flaps or landing gear until safe climb-outis assured.

AdvisoryCallouts

WindshearCaution

WindshearWarning


NOTE: Engine overboost should be avoided unlessthe airplane continues to descend and airplanesafety is in doubt. If overboost is required, adjustthrottles back to maximum rated thrust as soon assafety has been assured.

Overboosting engines while at high angle of attacknear airplane stall may cause engine stall, surge, orflameout.

Maintain escape attitude and thrust and delay re-tracting flaps or landing gear until safe climb-out isassured.

Partial system deactivation or compensation can beaccomplished for abnormal procedures as follows:

If steep approaches are to be performed (4 orgreater) EGPWS STEEP APPROACH should be en-abled and selected for these operations. This maybe accomplished automatically by on-board systemsor manually selected by a cockpit switch. When ac-tive, Mode 1 alerts are desensitized to compensatefor normally higher descent rates for these types ofoperation, eliminating related unwanted alerts. Ifimplemented with a cockpit switch, this requiresmanual deactivation.

When required to operate in close proximity to ter-rain (less than 2500’ above), Mode 2 alerts can bedesensitize or overridden by activating the FLAPOVER-RIDE switch to eliminate related unwantedalerts. This requires manual deactivation.

Mode 4 alerts can be reduced by activation of theFLAP OVER-RIDE switch. This is generally recom-mended when performing approaches with lessthan landing flaps selected. This requires manualdeactivation.

Mode 5 Glideslope alerts can be manually canceledwhen below 2000 feet Radio Altitude (Standard G/SCancel) by pressing the G/S Cancel switch (com-monly part of the amber caution annunciators

AbnormalProcedures

Mode 1ExcessiveDescentRates

Mode 2ExcessiveClosure toTerrain

Mode 4UnsafeTerrainClearance

Mode 5DescentBelowGlideslope


“BELOW G/S” or “GPWS”). This is typically selectedwhen an unreliable Glideslope is expected or whenmaneuvering is required during ILS final approach.The G/S Cancel is automatically reset followinglanding or if the aircraft climbs above the 2000 feet.

In some cases, an Alternate G/S Cancel is available.This allows the Mode 5 alerting to be canceled atany time and any altitude. In this configuration,which is defined only for certain aircraft types or byprogram pin, pressing the G/S Cancel switch in thecockpit has the effect of inhibiting Mode 5 alerting.It can be manually reset by again pressing the G/SCancel switch, or it is automatically reset followinglanding, if flap or gear state changes (i.e., down toup), or when the aircraft climbs above a predeter-mined altitude (defined for the aircraft type).Because of the nature of this type of G/S Cancel, acockpit indication of its activation is required.

Some aircraft may be configured with a G/S inhibitswitch. This switch is separate from the one dis-cussed above but also results in inhibiting Mode 5alerting. This switch is intended for selection dur-ing back course approaches to eliminate unwantedalerts that may result. If a discrete back course sig-nal is available from another system, this input tothe EGPWC may be connected to that system for au-tomatic Mode 5 inhibiting.

NOTE: Implementation of the Glideslope Canceland/or Inhibit inputs to the EGPWS varies. Verify aparticular application to determine the implemen-tation used.

Pressing the Terrain Inhibit switch inhibits TAD andTCF alerting and display, including Obstacles andPeaks when enabled. This is used when positionaccuracy is inadequate or when operating at air-ports not in the terrain database. Selection ofTerrain Inhibit does not cause the Terrain Inoperative

TerrainAlerting andClearanceFloor


EmergencyProcedures

annunciation unless the aircraft is wired for this tooccur. Terrain Inhibit requires manual deactivation.

The EGPWS Flap or Gear Over-ride, TAD/TCF In-hibit, or other switches (as installed) may be usedas required for an emergency situation (e.g., land-ing gear up).

For additional information refer to an applicableAFM or EGPWS AFMS or contact AlliedSignal.


Acronyms shall be interpreted as shown:

AFM Airplane FLight ManualAFMS Airplane Flight Manual SupplementAGL Above Ground LevelAHRS Attitude/Heading Reference SystemAOA Angle of AttackATC Air Traffic ControlBIT Built In TestCFIT Controlled Flight into TerraindB DecibelsDH Decision HeightEFIS Electronic Flight Instrument SystemEGPWC/S Enhanced Ground Proximity

Warning Computer/SystemsFAA Federal Aviation AdministrationFMS Flight Management SystemFPM Feet Per MinuteF/W Fail WarningGPS Global Positioning SystemGPWS Ground Proximity Warning SystemG/S GlideslopeHDOP Horizontal Dilution of PrecisionHFOM Horizontal Figure of MeritHIL Horizontal Integrity LimitHz Hertz (cps)ICD Interface Control DocumentILS Instrument Landing SystemINOP InoperativeIRS Inertial Reference SystemIVS Inertial Vertical SpeedMCP Mode Control PanelMCU Modular Concept UnitMFD Multi Function DisplayMLS Microwave Landing SystemMSL Mean Sea LevelMTC Minimum Terrain Clearance

SECTION 4

Definitions


PCMCIA Personal Computer Memory CardIndustry Association

PLI Pitch Limit IndicatorPPI Plan Position IndicatorPWS Predictive Windshear SystemQFE Corrected Baro. Altitude Relative To

Field ElevationRAIM Receiver Autonomous Integrity

MonitoringSAT Static Air TemperatureTA Terrain AwarenessTAD Terrain Alerting and DisplayTCAS Traffic Collision Avoidance SystemTCF Terrain Clearance FloorTERR TerrainTO/GA Takeoff/Go-AroundVDOP Vertical Dilution of PrecisionVFOM Vertical Figure of MeritVFR Visual Flight RulesVG Vertical GyroVHF Very High FrequencyWS Windshear


Dear AlliedSignal EGPWS Customer:

This form is a request for information that will allow AlliedSignal to notify youof future updates to your Enhanced Ground Proximity Warning System. Pleasecomplete the information below and fax the information sheet to AlliedSignalat 425-885-8722 or return via U.S. mail to:

AlliedSignal AerospaceAttn: Sandra SlickMail Stop 40, Dept. 134P.O. Box 97001Redmond, WA 98073-9701

Customer Information:Customer Contact: _________________________________________

Company Name: __________________________________________

Shipping Address: _________________________________________

_____________________________________________________

Phone Number: ___________________________________________

Fax Number: _____________________________________________

E-mail Address: ___________________________________________

Aircraft Information:

Aircraft Model ___________________________________________

EGPWS Part Number _______________ EGPWS Serial # _____________

Aircraft Model ___________________________________________

EGPWS Part Number________________ EGPWS Serial # _____________

Aircraft Model ___________________________________________

EGPWS Part Number________________ EGPWS Serial # _____________

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