the gliding federation of australia

8/14/2019 The Gliding Federation of Australia

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THE GLIDING FEDERATION OF AUSTRALIA

AEROTOWING MANUAL

GFA Aerotowing Manual December 2006


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AEROTOWING MANUAL

The reference document for the assessment of competency of tugpilots and the issuing of Towing Permits

Issue 3, December 2006

Published by:

The Gliding Federation of AustraliaLevel 1/34 Somerton Road,

Somerton, Victoria 3062,Australia

ABN 82 433 264 489

Phone: (03) 9303 7805Fax: (03) 9303 7960

Web: www.gfa.org.au

Copyright Gliding Federation of Australia, 2006

This issue of the Aerotowing Manual is approved by the Civil Aviation SafetyAuthority



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iTable of Contents

1. AEROTOWING - GENERAL POLICY................................................................. 12. PILOTS ............................................................................................................... 1

2.1 HOW TO OBTAIN A GLIDER TOWING PERMIT........................................ 1

2.2 VALIDITY AND RECENCY REQUIREMENTS FOR A GLIDER TOWINGPERMIT ..................................................................................................................2

3. CASA DELEGATES............................................................................................ 23.1 HOW TO BECOME A CASA DELEGATE.................................................... 23.2 VALIDITY AND RECENCY REQUIREMENTS FOR CASA DELEGATES... 3

4. GLIDER TOWING PERMITS - CHAIN OF COMMAND.................................... 35. GFA MEMBERSHIP OF TUG PILOTS ............................................................... 36. PRIVILEGES, LIMITATIONS AND VALIDITY OF GLIDER TOWING PERMITS 4

6.1 GENERAL.................................................................................................... 46.2 GLIDER TOWING PERMIT ......................................................................... 46.3 CROSS-COUNTRY TOWING...................................................................... 4

6.4 DOUBLE TOWING APPROVAL .................................................................. 46.5 OUTLANDING RETRIEVE APPROVAL ...................................................... 46.6 VALIDITY OF GLIDER TOWING PERMITS ................................................ 46.7 VALIDITY OF CAR 149 GLIDER TOWING DELEGATIONS....................... 5

7. PHILOSOPHICAL APPROACH TO TOWING GLIDERS.................................... 57.1 DESIRABLE BACKGROUND ...................................................................... 57.2 ASSESSMENT OF SUITABILITY ................................................................ 67.3 APPLICATION OF THE PROCEDURES IN THIS MANUAL ....................... 77.4 THE RELATIONSHIP OF GLIDING EXPERIENCE TO SUCCESSFULGLIDER-TOWING .................................................................................................. 7

8. COMPETENCY STANDARDS TO BE DEMONSTRATED FOR ISSUE OFGLIDER TOWING PERMIT........................................................................................ 7

8.1 NORMAL PROCEDURES ........................................................................... 78.1.1 Ground Preparation ..............................................................................78.1.2 Take-off................................................................................................. 88.1.3 Climb..................................................................................................... 88.1.4 Release................................................................................................. 98.1.5 Descent................................................................................................. 98.1.6 Joining Circuit ....................................................................................... 98.1.7 Approach and Landing........................................................................ 108.1.8 Cruising on Tow.................................................................................. 10

8.1.9 Descending on Tow ............................................................................ 108.1.10 Further Considerations ....................................................................... 108.2 ABNORMAL PROCEDURES..................................................................... 10

8.2.1 Stop signal on take-off run................................................................ 108.2.2 Partial power failure ............................................................................ 118.2.3 Glider airbrakes (or tail-chute) open during climb ............................... 118.2.4 Order to glider pilot to release............................................................. 118.2.5 Glider unable to release...................................................................... 118.2.6 Glider and tug unable to release......................................................... 118.2.7 The tug upset ................................................................................... 11

8.3 DOUBLE TOWING APPROVAL ................................................................ 11

8.3.1 Procedures ......................................................................................... 118.3.2 Pilot qualifications and operational requirements................................ 12



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ii8.3.5 Notification.......................................................................................... 13

8.4 OUTLANDING RETRIEVE APPROVAL .................................................... 138.4.1 Prerequisites....................................................................................... 138.4.2 Ground preparation............................................................................. 138.4.3. Notification ............................................................................................14

9. EXPANDED GUIDELINES FOR GLIDER TOWING PERMIT........................... 149.1 NORMAL PROCEDURES ......................................................................... 14

9.1.1 The purpose of an aerotow................................................................. 149.1.2. Daily inspection..................................................................................... 149.1.3 Performance of tug/glider combination ............................................... 159.1.4 Awareness of glider limitations ........................................................... 159.1.5 Glider airbrakes .................................................................................. 169.1.6 Greater chance of engine failure in tugs ............................................. 169.1.7 Minimum fuel for tow........................................................................... 179.1.8 Pre take-off checks............................................................................. 179.1.9 Ground signals.................................................................................... 18

9.1.10 Take-off technique .............................................................................. 199.1.11 The steady climb................................................................................. 219.1.12 High-tow and low-tow.......................................................................... 229.1.13 Boxing the slipstream ....................................................................... 249.1.14 Releasing from tow............................................................................. 259.1.15 The descent ........................................................................................ 259.1.16 Landing............................................................................................... 269.1.17 Baulked approaches and go-arounds ................................................. 269.1.18 If in doubt, drop the rope..................................................................... 269.1.19 Approaching too low ........................................................................... 279.1.20 Cruising on tow................................................................................... 279.1.21 Descending on tow ............................................................................. 289.1.22 The Non-Manoeuvring Area (NMA) .................................................... 299.1.23 Some suggested towing patterns........................................................ 29

9.2 ABNORMAL PROCEDURES..................................................................... 309.2.1 Stop signal during take-off run.......................................................... 309.2.2 Engine failure...................................................................................... 309.2.3 Gliders airbrakes coming open on ground-run................................... 319.2.4 Gliders airbrakes coming open during climb ...................................... 319.2.5 Other reasons for poor rate of climb ................................................... 319.2.6 Order to glider pilot to release - the wave-off signal ......................... 32

9.2.7 Glider unable to release...................................................................... 329.2.8 Double-release failure - landing on tow (optional - not mandatory forPermit) 33

9.3 THE TUG UPSET.................................................................................... 3410. EXPANDED GUIDELINES FOR OUTLANDING RETRIEVE APPROVAL........ 36

10.1 GENERAL..................................................................................................3610.2 PRELIMINARIES ....................................................................................... 3610.3 THE LANDING........................................................................................... 37

10.3.1 Lack of markings................................................................................. 3710.3.2 Obstacles on the approaches ............................................................. 3710.3.3 Lack of wind information ..................................................................... 37

10.3.4 Unreliable information and pressure to perform.................................. 3710.3.5 Apply the glider pilots five S rule ...................................................... 37



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iii10.3.6 Further reading ................................................................................... 3910.3.7 Removing the rope ............................................................................. 39

10.4 THE TAKE-OFF......................................................................................... 4010.4.1 Pacing out the paddock ...................................................................... 4010.4.2 Factors affecting the take-off .............................................................. 40

10.4.3 Take-off technique .............................................................................. 4111. THE MANAGEMENT OF ENGINES AND RELATED ITEMS IN THE GLIDER-TOWING ROLE........................................................................................................ 42

11.1 AIR-COOLED HORIZONTALLY-OPPOSED ENGINES (LYCOMING,CONTINENTAL, ETC).......................................................................................... 42

11.1.1. General ............................................................................................... 4211.1.2 Daily inspections................................................................................. 4211.1.3 Pilot operation..................................................................................... 44

11.2 AIR-COOLED IN-LINE ENGINES (GYPSY MAJORS, ETC.) .................... 4611.2.1 General ............................................................................................... 4611.2.2 The Armstrong starter....................................................................... 47

11.3 LIQUID-COOLED ENGINES...................................................................... 4911.3.1 Partially liquid-cooled engines ............................................................ 51

11.4 PROPELLERS...........................................................................................5211.4.1 Fixed pitch propellers.......................................................................... 5211.4.2 Variable-pitch and two-speed propellers............................................. 5211.4.3 Constant speed propellers.................................................................. 5311.4.4 Cowl flaps ...........................................................................................53

11.5 FUEL REQUIREMENTS, AVGAS AND MOGAS....................................... 5411.6 ROPES, RINGS AND WEAK-LINKS. ........................................................ 54

12. APPENDIX - MISCELLANEOUS INFORMATION AND STANDARD FORMS . 5712.1 A TYPICAL GLIDER-TOWING PERFORMANCE CHART (PAWNEE 235)

5712.2 CUTAWAY OF A TYPICAL TUG ENGINE (LYCOMING 0-540) ................ 5812.3 EXTRACT FROM CIVIL AVIATION REGULATIONS - DAILY INSPECTIONSCHEDULE.......................................................................................................... 5912.4 EXTRACT FROM CIVIL AVIATION REGULATIONS - PERMISSIBLEMAINTENANCE BY PILOTS ................................................................................ 6112.5 COMPETENCE CHECK LIST - INITIAL GLIDER-TOWING PERMIT........ 6212.6 COMPETENCE CHECK LIST - DOUBLE TOWING APPROVAL.............. 6412.7 COMPETENCE CHECKLIST - OUTLANDING RETRIEVE APPROVAL... 6512.8 GLIDER TOWING PERMIT, DOUBLE TOWING AND OUTLANDING

RETRIEVE APPROVALS..................................................................................... 6612.9 CIVIL AVIATION REGULATIONS (CARS) 92 AND 93 - USE OFAERODROMES....................................................................................................6712.10 CIVIL AVIATION ADVISORY PUBLICATION (CAAP) 92-1, GUIDELINESFOR AEROPLANE LANDING AREAS................................................................. 6812.11 EXTRACT FROM AERONAUTICAL INFORMATION PUBLICATION(AIP) - DAYLIGHT/DARKNESS GRAPHS (END OF DAYLIGHT ONLY) ............. 7412.12 CONVERSION OF ARC TO TIME ......................................................... 7812.13 CROSSWIND COMPONENT CHART.................................................... 79

13. SELF-TEST QUESTIONS AND ANSWERS..................................................... 8013.1 GLIDER-TOWING PERMIT QUESTIONS.............................................. 80

13.2 GLIDER TOWING PERMIT ANSWERS ................................................. 8413.3 DOUBLE TOWING APPROVAL QUESTIONS....................................... 88



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iv13.4 DOUBLE TOWING APPROVAL ANSWERS .......................................... 8913.5 OUTLANDING RETRIEVE APPROVAL QUESTIONS ........................... 9013.6 OUTLANDING RETRIEVE APPROVAL ANSWERS .............................. 91

NOTES FOR DELEGATES...................................................................................... 93



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1

AEROTOWING MANUAL

1. AEROTOWING - GENERAL POLICY

The aerotowing of gliders is only permitted by pilots whose competence forthe task has been assessed and who hold a Glider Towing Permit. ThePermit is subject to certain recency requirements.

A Glider Towing permit is issued by a Delegate of the Civil Aviation SafetyAuthority (CASA) under Civil Aviation Regulation (CAR) 149 only when thedelegate has assessed the pilot as competent in glider towing operations.

2. PILOTS

HOW TO OBTAIN A GLIDER TOWING PERMITCandidates for glider-towing approval must hold a Private or higher categorylicence and a minimum of 100 hours total aeronautical experience, of whichat least 40 hours shall be on CASA-registered Australian or overseas-registered fixed-wing aircraft. Of the remaining experience, glider, military(fixed wing) and ultralight (3-axis control) flying time may be counted in fulltoward the total aeronautical experience.

As glider tugs exist in a wide variety of types, the candidate must hold theendorsements (e.g. tailwheel, constant-speed) applicable to the type to be

used for towing.

A gliding certificate is strongly recommended and may be mandatory insome clubs. As a minimum, the candidate must be in current practice as aglider pilot in an aerotow environment before issue of a towing permit. Thiscurrency shall include exposure to the various tug signals, to ensurefamiliarity from the glider end.

When the above conditions are satisfied, the candidate may commenceglider-towing in a double-control aircraft with the CASA delegate or anexperienced tug pilot nominated by a delegate as pilot in command. The

applicant must demonstrate competency to the CASA delegate and thedelegate will issue a Glider Towing Permit if satisfied the pilot is competent.

A Glider Towing Permit authorises a pilot to tow one glider at a time frommarked aerodromes and/or established gliding sites only, unless furtherprivileges are annotated. The privileges, limitations and revalidationrequirements of a Glider Towing Permit are notified on the Permit.



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2VALIDITY AND RECENCY REQUIREMENTS FOR A GLIDER

TOWING PERMIT

A Glider Towing Permit remains valid as long as the pilots licence (i.e.medical certificate and flight review) is current and the pilot meets recency

requirements. The recency requirements for glider towing are notified onthe Glider Towing Permit.

Note: The Glider Towing Permit is issued by the CASA delegate for theperiod stated on the Permit. This is normally while the holder of the Permitholds a valid licence and medical certificate.

The longer a tug pilot has lacked the recency requirements of the Permit,the longer it is likely to take to satisfy the delegate of his/her competence toobtain recency by this means.

3. CASA DELEGATES

HOW TO BECOME A CASA DELEGATE

Experienced pilots may make an application to become a CASA delegate forthe issue of Glider Towing Permits. Application will be to CASA via the GFARTO/Operations responsible for the applicants club and with therecommendation of the GFA Chief Technical Officer Operations. The GFAwill expect delegates to be endorsed by a gliding club or organization.

Experience requirements to be recommended by GFA to hold a CASAdelegation are as follows:-

A Private or higher category licence;

Significant relevant aeronautical experience, including;

o A minimum of 175 hours total aeronautical experience, at least100 of which must be in aeroplanes;

o A minimum of 50 hours glider towing experience (more if overallexperience is close to the minimum);

Must have held a Glider Towing permit, with privileges includingoutlanding retrieve approval, for at least twelve months;

Must have a demonstrated aptitude for assessing the competence ofpilots for the glider towing task.

If the above conditions are satisfied, and subject to the recommendation of arepresentative of the GFA, the candidate may apply for a CASA delegationas described above. Successful applicants will be appointed as CASAdelegates by means of a CASA Instrument of Delegation.



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3Refer also to the notes for CASA delegates in Appendix 1 to this manual onpage 93.

VALIDITY AND RECENCY REQUIREMENTS FOR CASADELEGATES

A CASA Instrument of Delegation is valid for the period stated in theInstrument of Delegation. Recency requirements are the same as for aGlider Towing Permit.

Refer also to Notes for CASA delegates in Appendix 1 to this manual onpage 93.

4. GLIDER TOWING PERMITS - CHAIN OF COMMAND

To sum up Sections 2 and 3, the chain of command for Glider Towing

permits is as follows :-

CASA delegates

Holders of CASA Instruments of Delegation for the issue of Glider towingpermits. Subject to renewal by CASA (normally on GFA recommendation),which may entail CASA surveillance of the applicants activities.

Tug pilots

Assessed by a CASA delegate in accordance with the procedures described

in this manual. Issued with Glider Towing Permit by CASA delegate. Ifrecency requirements are met the holder may exercise the privileges of thePermit. If the six-month recency requirements are not met (see 13.1.3) thetug pilot must satisfy a delegate of his/her competence, which the delegatemay signify by signing the holders personal flying log book.

5. GFA MEMBERSHIP OF TUG PILOTS

Although it is not strictly a requirement that a tug-pilot be a member of theGliding Federation of Australia, such membership confers the protection ofthe various GFA insurances on the pilot and becoming a member would be

a wise move.

It is important to note that a tug pilot who is not a member of the GFA has noprotection from the Federations Broad-Based Liability (BBL) or ContingentLiability policies.



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4

6. PRIVILEGES, LIMITATIONS AND VALIDITY OFGLIDER TOWING PERMITS

GENERAL

A Glider Towing Permit authorises the holder to act as pilot in command ofan aeroplane in glider-towing operations in such a way as not to endangerany other traffic. It is recommended that a tug aircraft should not be flownwithin 100 metres horizontally or 200 feet vertically of another aircraft,except in the case of establishing such separation from a glider or glidersreleased by that tug aircraft.

GLIDER TOWING PERMIT

The holder of a Glider Towing Permit in its simplest form may tow a single

glider in operations from a Licensed Aerodrome or from an established andsuitably marked gliding site approved by the GFA and which meets therequirements of an Aircraft Landing Area.

CROSS-COUNTRY TOWING

Cross-country glider tows from and to such aerodromes or sites asdescribed in 6.2 are permitted by a pilot holding the appropriate licence forcarrying out such flights (This means pilots holding a private or highercategory licence, or the old Unrestricted licence may carry out such tows.Pilots still holding the old Restricted licence may not carry out such tows,

unless the planned destination is within a designated training areaassociated with the departure aerodrome).

No double towing or outlanding retrieves are permitted unless theseactivities are authorised by the holders Glider Towing Permit. See below.

DOUBLE TOWING APPROVAL

The holder of a Glider Towing Permit which includes double towing may towtwo gliders in accordance with the procedures laid down in this manual andnotified on the approval document.

OUTLANDING RETRIEVE APPROVAL

As notified by the approval document, the holder of a Glider Towing Permitwhich includes outlanding retrieve approval may launch gliders fromunmarked paddocks and is authorised to land in such paddocks solely forthe purpose of launching a glider, subject to the approval of the land-owner.

VALIDITY OF GLIDER TOWING PERMITS

Glider Towing Permits shall be valid for the period shown on the Permit.

This is normally the period of validity of the holder's Flight Crew Licence(Aeroplanes), subject to the recency requirements of the Permit being met.



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5VALIDITY OF CAR 149 GLIDER TOWING DELEGATIONS

CASA Instruments of Delegation are valid for the period shown on theInstrument, provided the delegate holds a current Glider Towing permit, andare subject to the conditions specified in the Instrument of Delegation.

CASA will normally seek the GFAs recommendation before issuing orrenewing a delegation.

7. PHILOSOPHICAL APPROACH TO TOWING GLIDERS

Although it seems to state the obvious, the sole task of the tug pilot is tolaunch gliders as safely and efficiently as possible. The reason it ismentioned here is that tug pilots sometimes forget this basic fact and seemto acquire a belief that the glider is almost secondary to the business offlying a tug aircraft. Thus we get problems like towing too far away, towing

downwind, towing into the sun for long periods, rough handling, excessivelysteep turning, "cowboy" descent patterns, etc. Tug pilots may sometimesneed reminding that they exist solely for the benefit of the glider pilots and ifthey do not adhere to legal requirements and/or the operating proceduresset by the club, they may be shown the door.

DESIRABLE BACKGROUND

Most tugs are taildraggers and it is becoming increasingly difficult to obtaintraining on this type of aircraft in the mainstream flying schools, almost allschool aircraft being nosewheel designs. A small number of flying schoolsspecialise in taildragger endorsements, often together with aerobatics.Alternatively, new pilots considering glider-towing as another string to theirbow are strongly recommended to join the Australian Ultralight Federation(AUF) and do some flying at one of their schools in one of the moredemanding taildragger machines such as the Lightwing or Skyfox, as theseare likely to have flying characteristics (but not the mass) closer to the typeof aircraft they will be using to tow gliders.

Experience has shown that the best tug pilots are light aircraft pilots with astrong VFR background in aircraft which are quite demanding to fly, such asAusters, Cessna 180s and the ultralights mentioned above. Pilotsexperienced on such aircraft tend to have good "hands on" skills and theirlookout is of a good enough standard for gliding clubs to rely on.

Another reason to insist on a good background in a relevant aircraft type isthat a tug pilot has to put up with a pressure to fly which was not presentbefore. For example, if conditions get a bit tricky (e.g. crosswind), the gliderpilots may be quite happy to keep flying but the tug pilot may never haveflown in such conditions before. With glider pilots breathing down his neckto be launched, it is much more difficult to choose to stop flying than it wasbefore. This is where any lack of experience becomes apparent, sometimes

resulting in an accident or incident. Delegates may be disinclined to issue



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6Permits to pilots who lack the experience and/or competence to handle suchconditions, or recommend they consolidate their skills with a flying school.

Additionally, it is worth remembering that the kind of turbulent conditions thatupset some power-pilots are the very conditions sought by glider pilots and

a tug pilot will be going up and down all day in these conditions, rather thanclimbing to cruise in the smooth air on top of the turbulent layer.

Finally, delegates and gliding clubs should beware of pilots who havelearned to fly on tricycle-gear aircraft, then do a minimal conversion to aneasy-to-fly taildragger like a Citabria and appear at a gliding club wanting tostart a towing conversion. If such pilots have a strong gliding background,they are usually not a problem, gliders needing good hands-on skill tooperate safely and many of them being of taildragger design. If they haveno gliding background and only a minimal taildragger conversion, they needto be watched very carefully. Although everybody has to start somewhere

and some pilots do adapt very well, others never really cope and either needextra work back at the flying school or decide that aerotowing is not forthem.

ASSESSMENT OF SUITABILITY

Keeping in mind the desirable background outlined above, the CASAdelegates task is to make an assessment of the pilot's suitability for theaerotowing task. Most CASA delegates are not powered flight instructorsand therefore have no privileges to train and endorse pilots for taildragger orconstant-speed conversions. Their job in most cases will be simply to make

an assessment of whether the person really has the background andaptitude to tow gliders, or whether further taildragger training back at theflying school is required.

Unfortunately, a common complaint made by CASA delegates is that pilotsfresh from flying training are often good on procedures and use of radio, butnot so good in raw flying ability and airmanship. Under the pressure ofhaving a glider on the back and coping with having to think for two aircraftinstead of one, a marginal pilot's airmanship may fall to a negligible level. Itis hard to imagine a more hazardous situation than the command pilot of atug/glider combination who is too stressed to look out. Tug aircraft climb

and descend through a very busy part of the sky many times in a day andthe pilot's airmanship must be of the finest quality.

Correct engine-handling is important. Light aircraft engines are air-cooledand spend most of their lives at constant power and a constant cruisingspeed. In this environment air-cooling is very effective, as there are no rapidchanges to power or speed. Cylinder-head and oil temperatures remainconstant and the engine is thermally stable.

The demands of glider-towing are quite different and very demanding on anengine. The cycle of high power, low airspeed, followed by lower power,

higher airspeed, results in a "thermal gradient" from front to rear of theengine. This is worsened if a pilot allows a very rapid speed build-up and/or



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7closes the throttle too quickly after the glider has released, adding theproblem of "thermal shock" to the gradient problem already present.

Any pilot who shows signs of rough handling of the throttle, and is notamenable to this characteristic being corrected, will not make a good tug

pilot and is likely to cost the club dearly if allowed to escape onto the tugpilot roster. Gliding clubs should consider carefully whether they want suchpilots to be in charge of a major asset before they roster them for dutywithout re-training.

APPLICATION OF THE PROCEDURES IN THIS MANUAL

If the pilot is assessed as being suitable material to become a tug pilot, theprocedures outlined in this manual may be applied. The procedures areself-explanatory; the only comment needed here is to ensure that none of itis skimped.

THE RELATIONSHIP OF GLIDING EXPERIENCE TOSUCCESSFUL GLIDER-TOWING

Although not a requirement that a tug pilot also retains currency as a sologlider pilot (but it may be mandatory in some clubs), there is generalagreement that the best tug pilots are also glider pilots. Glider pilots areskilled at "reading" the sky. They are aware of areas of lift and sink andknow how to seek out or avoid such areas. This kind of ability is valuable fora tug pilot, as maximum use of lift during the climb and managing to findareas of sink on the descent can greatly reduce the time taken for each tow.

This maximises efficiency and reduces costs, but must never be at theexpense of top-quality airmanship, especially lookout, at all times.

8. COMPETENCY STANDARDS TO BEDEMONSTRATED FOR ISSUE OF GLIDER TOWINGPERMIT

NORMAL PROCEDURES

There is no specific number of hours or flights to be completed; it is left to

the discretion of the CASA delegate to issue a Glider Towing Permit whenthe applicant demonstrates the necessary level of competence.

An applicant must be able to show understanding and application of theknowledge and skills listed below.

8.1.1 Ground Preparation

The tug pilot's responsibility for the overall safety of the towing operation,as command pilot of the tug/glider combination.

The tug's Flight Manual Towing Supplement and Towing PerformanceChart, if applicable.



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8 The requirements of the GFA Operational Regulations and Operations

Manual in respect of the aerotowing of gliders.

Preparation of aircraft for glider towing operations, including inspection oftug aircraft release mechanism, mirrors, ropes, release rings and weak

links.

The glider's requirements in aerotowed flight, including maximum andminimum speeds in unballasted and ballasted configurations.

The implications of glider towing on the fuel consumption of the tugaircraft.

Minimum rope lengths for the single and, if applicable, double towing ofgliders.

Weak link requirements.

Ground signals applicable to glider towing.

Assess the take-off performance required when towing a glider againstthe distance available under prevailing conditions.

8.1.2 Take-off

Correct response to all ground signals.

Monitor expected take-off performance and take appropriate action in theevent of not achieving expected performance.

Demonstrate ability to take-off in a crosswind of not less than 2/3 of themaximum allowable crosswind for the type.

Use of mirrors to monitor glider position.

8.1.3 Climb

Fly primarily by attitude to maintain a speed appropriate to the tug/glider

combination and the conditions, responding only to trends in airspeedand smoothing out transient changes in speed caused by turbulence.

Correct handling of engine, using power settings appropriate to theengine handling notes and the requirements of the tug/glidercombination.

Maintain a good lookout and adequately compensate for any aircraftblind spots. This means avoiding long periods at a constant headingand, in high-wing tugs, raising a wing to check that the airspace is clearbefore turning.



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9 Selection of towing pattern which minimises towing into the sun, takes

advantage of forced landing options, stays within gliding range of thefield and makes maximum use of any lift which is available. The towingpattern should also take into account the wind velocity and likely releaseposition.

Avoidance of conflict with other traffic, glider and power, in the circuitarea.

Continue to monitor glider position by use of mirrors.

Recognise high-tow and low-tow and transition between the two.

Control the tug attitude during boxing the slipstream by the glider.

Maintain correct towing attitude and speed regardless of whether glider

is in high or low tow, is out of position or is transiting between towingpositions.

Ensure tug attitude and heading are controlled when glider is taken asfar out of position as practicable and safe, in order to demonstrate to tugpilot the required action under these circumstances.

8.1.4 Release

Confirm glider release by use of mirrors and, if possible and necessary,by physically turning round in seat to view glider directly.

Ensure airspace below tug aircraft is clear to commence descent.

8.1.5 Descent

Commence descent, maintaining heading or turning left as required,avoiding abrupt manoeuvres or shock-cooling of engine. Do not turnright, as some tugs (e.g. Cessnas, Maules, two-seat Pawnees, etc), havea blind spot on the right side of the cockpit and it is not possible toadequately clear the airspace into which the aircraft is just about tocommence descent.

Selection of correct airspeed and power settings.

Selection of descent pattern appropriate to the site, wind velocity andother traffic.

Maintain adequate lookout at all times, compensating for aircraft blindspots.

8.1.6 Joining Circuit

Correct circuit entry, maintaining good lookout, integrating with othertraffic and making appropriate radio calls.



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10 Carry out pre-landing checks.

Selection of suitable landing area, with due regard for any specialrequirements which may be in force.

8.1.7 Approach and Landing

Recognition of trailing rope and the required obstacle clearance.Awareness of option to drop rope if required.

Go-around procedures.

8.1.8 Cruising on Tow

Gentle transition into cruise and gentle reduction of power, in order toavoid slack developing in the rope.

Selection of appropriate speeds in accordance with conditions and gliderplacard limitations.

8.1.9 Descending on Tow

Gentle closure of throttle, avoiding slack in rope and giving glider pilottime to adjust airbrake setting to maintain position.

Maintain adequate lookout and select descent path appropriate to therequirements of the combination.

If intending to land on tow, remember obstacle clearance in relation tothe position of the glider and the selection of intended touchdown point.

8.1.10 Further Considerations

The foregoing list of normal (non-emergency) aerotowing procedures isbased on the towing of one glider behind the tug aircraft.

Note: Section 8.3 provides for separate and additional competencies tobe demonstrated for double towing to be included on a Glider Towing

permit.

ABNORMAL PROCEDURES

All the following procedures should be carried out in practice.

8.2.1 Stop signal on take-off run

Release glider, monitor mirrors and be acutely aware of possibility ofglider running into back of tug.



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118.2.2 Partial power failure

(a) Tug on ground

Release glider. Keep tug moving if enough power is available to do so.

Monitor mirrors.

(b) Tug airborne

Release glider, with due regard for strip available and/or the options forthe glider pilot, depending upon height and position. Land the tug inwhatever area has been pre-selected for the purpose.

Note: Procedure (a) should be followed if the tug pilot detects that theglider's airbrakes have come open during the ground run.

8.2.3 Glider airbrakes (or tail-chute) open during climb

Assess height and position. Consider whether to give rudder-wagglesignal or get rid of glider.

8.2.4 Order to glider pilot to release

Weigh up whether to release glider without warning or give a wing-waggle.

8.2.5 Glider unable to release

Glider flown out to left of tug. Acknowledgment given by tug pilot.

8.2.6 Glider and tug unable to release

Demonstration of this exercise is optional and will not be required forissue of a Glider Towing Permit.

8.2.7 The tug upset

Definitely not to be practised! However a tug pilot needs anunderstanding of the dynamics of the upset manoeuvre and the

necessary preventative measures. See also Section 9.3 for furtherinformation on tug upsets.

DOUBLE TOWING APPROVAL

8.3.1 Procedures

Requirements for double towing are as follows:-

Adequate strip length, width and obstacle clearance.

Wingtip holders to be positioned at outer wings.



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12 Forward signaller essential.

Water ballast must not be carried.

The short rope to be a minimum of 35 metres long and the long rope

minimum 65 metres long. Pilot on short rope should have had some priorpractice in flying on a shorter-than-normal rope. If possible, ropes should beconnected to the tug aircraft in such a way that, if jettisoned by the tug pilot,both ropes will separate. The degree of difficulty in arranging this varieswith aircraft type and individual release installation.

Prior to take-off, if there is a light crosswind, the glider on the short ropeshall be placed on the upwind side of the tug, to minimise the chance ofground-looping across the front of the glider on the long rope. If thecrosswind is strong, it is recommended that a double tow should not becarried out.

The glider with the most efficient ground-braking system (skid orwheelbrake) shall be placed on the long rope, and the more experiencedpilot shall fly this glider, in case the short rope breaks during the take-off run.

When the combination is airborne, both gliders shall fly directly behind thetug, the glider on the short rope flying in high-tow, the glider on the long ropein low-tow. The tug shall not turn until both gliders are settled in line-astern.

At the releasing stage, the glider in high tow on the short rope shall releasefirst and ensure that an immediate clearing turn is made.

In the event of a wave-off, the gliders release and break to the respectivesides from which they commenced the launch.

In the event of release failure in the first glider, the pilot shall fly the gliderout to the left (remaining in high-tow) to warn the tug pilot and the pilot of theother glider. Upon receipt of acknowledgment from the tug pilot, the glider isreturned to the normal high-tow position, whereupon the glider on the longrope releases and clears away. The tug pilot then releases the short-ropeglider from the tug end.

If the glider on the long rope has not released and cleared away within 10seconds of the glider on the short rope returning to the high-tow position, thetug pilot shall assume that it has also failed to release and shall release theropes at the tug end.

8.3.2 Pilot qualifications and operational requirements

Pilots wishing to undertake double towing must be in current flying practicein glider-towing operations. The foregoing procedures must be strictlyadhered to and pilot must receive an adequate briefing from a CASAdelegate before undertaking double towing.



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138.3.5 Notification

Notification that a pilot is approved to carry out double towing as pilot incommand is by issue of the appropriate Permit by a CASA delegate.

OUTLANDING RETRIEVE APPROVAL8.4.1 Prerequisites

A candidate for outlanding retrieve approval must have a minimum of 30hours glider towing experience as a tug-pilot before undertaking anassessment to qualify for outlanding retrieves. Note that the stipulated 30hours should be regarded as a MINIMUM, as experience has shown thatconsiderably more than this is desirable, unless the candidate has specialexperience relevant to the outlanding retrieve task, such as recentexperience as a cross-country glider pilot, with associated outlandings.

8.4.2 Ground preparation

Understanding of Civil Aviation Regulation (CAR) 92 and Civil AviationAdvisory Publication (CAAP) 92-1, which explain the requirements foruse of an airfield which is not a public or military aerodrome. SeeSection 12 of this manual for these documents.

Understanding of the reduced speed during cross-country towing (ifapplicable) and its effect on fuel consumption, plus an understanding ofdaylight/darkness graphs and the calculation of local last light.

Awareness of the effect of local weather conditions and surroundingterrain on the time of onset of actual darkness, as opposed to officiallast light.

Understanding of normal precautionary search procedures, particularly inrespect of assessment of suitability of paddocks with respect to size,slope, surface, stock and surroundings, with special attention given toSWER lines and their effect on selection of takeoff and approach paths.

If rope is attached to tug for the outbound trip, dropping of rope for

paddock landing. Assessment of adequate length for take-off, using allapplicable factors, including "P" Charts if available.

Practice in taking off without ground crew, using suitable agreed signals.Assessment of length of crop/grass in paddock and an understandingthat the tug-pilot is not obliged to land in a paddock considered by thatpilot to be unsuitable.

Understanding that total fire bans preclude the possibility of an aerotowretrieve. Understanding of responsibility to land owners.



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148.4.3. Notification

Notification of outlanding retrieve approval shall be by the issue by a CASAdelegate of a Glider Towing Permit including this privilege.

9. EXPANDED GUIDELINES FOR GLIDER TOWINGPERMIT

This section is a how to do it expansion of the procedures in the previoussection.

NORMAL PROCEDURES

9.1.1 The purpose of an aerotow

The purpose of an aerotow is to provide the glider pilot with a safe and

efficient launch to his/her chosen height and position. Although this is notdifficult, there are many differences between flying around without a glideron the back in comparison with the task of providing the best possiblelaunch for your trusting client.

The differences may be summarised as follows.

9.1.2. Daily inspection

The normal daily inspection is carried out on the tug aircraft in accordancewith Schedule 5 of the Civil Aviation Regulations 1988 (Amendment No 2,

August 1999), with the addition of the following items:-

1. Tow-release. Inspect for integrity of attachment, cleanliness,serviceability and proper connection from the cockpit. Checkserviceability by attaching a rope with the approved rings fitted, andreleasing it under tension, for which an assistant is required. First tug-pilot to fly the aircraft on any day must sign the Maintenance Releasethat the release has been inspected in accordance with AD Supp. 8.

2. Tow-ropes. These should be of the correct length (55 metres for towinga single glider) and must be fitted with approved rings. Ropes should not

be frayed and any doubtful sections replaced or, in the case of joins, re-spliced.

3. Weak-links. One of these must be fitted at the tug end. The maximumbreaking strength for tug aircraft is 450 kgs, except for the Pawnee 235,which is 750 kgs.

4. Mirrors. It is a requirement (GFA Ops Reg 8.4.3) that at least one mirroris fitted to a tug. It is more usual to have two. They may be mounted onwing-struts or on the fuselage sides. It is normal practice to align onemirror on the high-tow position and the other on the low-tow position.

Check them for cleanliness, broken glass and security of attachment.



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155. Cleanliness of transparencies. Although important at any time,

cleanliness of the windscreen and side-windows is of paramountimportance for aerotowing. Scratches, bugs and oil-streaks play havocwith detection of other aircraft. Make sure everything is absolutely asclean as possible.

9.1.3 Performance of tug/glider combination

When a glider is hooked onto the back of a tug aircraft, the all-up weight ofthe combination obviously increases. Gliders vary in weight from thelightweight single-seaters of around 300 to 400 kgs (or even lighter) to singleor two-seat monsters of up to 750 kgs.

The higher all-up weight of the tug/glider combination means a considerablylonger ground-run than the basic aircraft. There is also a reduced climb-rateto consider. The combination of the two results in a major reduction in

obstacle clearance, which must be taken into account on every launch.

All aircraft approved for glider-towing have Flight Manual supplements forthe purpose. Most tug aircraft have revised Performance Charts ("P"Charts) for the glider-towing role incorporated into their supplements. SeeSection 12.1.

If the tug has a revised "P" Chart, it should be used to pre-plan the take-off.If it has not got one (the Chipmunk and Tri-Pacer are two examples), followthe guidelines in the Flight Manual supplement, which typically suggest thatthe take-off distance to 50 feet without a glider on the back should be

factored by 1.5 when towing a single-seat glider and doubled for a two-seater.

Important note. When considering glider weight, what you see is notnecessarily what you get. High-performance gliders carry water-ballast intheir wings for enhancing their cross-country performance. Some of themcan carry more than 200 kgs of water, or the weight of two big persons.Since there is no means of telling the difference between a "dry" and a "wet"glider by its appearance (apart from a few gliders on which the wings droopnoticeably when they are ballasted), it is obviously important to check theweight of the glider by asking the pilot before attempting to tow it.

9.1.4 Awareness of glider limitations

All gliders have a minimum speed for towing. This is usually governed bythe wing-loading. Very heavy gliders will need to be towed much faster thanlightly loaded gliders and tug-pilots need to get used to the range ofminimum speeds of the gliders they tow, and above all to ask if they don'tknow.

Gliders also have a maximum speed for aerotowing. This is a structurallimitation established during certification and gliders must be kept below this

limit. This means another speed to check and memorise for each type.



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16The most critical gliders in terms of maximum speed are some of the olderdesigns, where the tug may have to slow down considerably to preventoverspeeding of the glider. This makes the tug more difficult to fly, themargin above the stall reduced, control responses degraded and enginecooling often suffering as well. These speed-limited gliders should not be

towed by inexperienced tug-pilots, as the operation needs a high degree ofskill and a broad background of glider-towing.

Although strictly more of a problem for a glider pilot than a tug pilot. somegliders (e.g. Std Libelle, Hornet) suffer considerable speed errors due to therope occupying the same hole in the nose as the pitot head. Just keep it inmind.

9.1.5 Glider airbrakes

Many power pilots will be unaware of the existence of airbrakes on gliders.

These devices, used to control the final approach to land, have a particulartrap which may catch a tug-pilot. In the closed position, airbrakes blend intothe wings, but they may not necessarily be locked in that position. There isa very subtle difference in appearance between airbrakes which are closedand flush, but not locked, and those which are locked properly in theircorrect position for take-off. The learning tug-pilot would be wise to observea number of gliders and store this subtle difference away for future use.

If an aerotow commences, and the glider's airbrakes are closed but notlocked, they will probably suck slowly out and remain undetected by theglider pilot. The effect of open airbrakes on the take-off and climb

performance of the combination is drastic and will completely compromisethe carefully-laid plans made before take-off. The tug-pilot should cultivatethe habit of checking for open airbrakes as soon as practicable during thetake-off.

9.1.6 Greater chance of engine failure in tugs

Although the evidence that tug engines are likely to fail more often thanother light aircraft is anecdotal rather than based on hard facts, they do leadquite a hard life and there may possibly be an enhanced risk of failure. Thiscould arise for a number of reasons.

1. A large number of hot/cold cycles resulting from a full-throttle climb,followed immediately by a partial-power descent. The climb in particular,because it is often at less than the optimum climb speed for the type,may result in much heat being generated and this may result in greaterwear and possible valve damage.

2. The use of Mogas (motor car gasoline) in some tug engines, with itshigher risk of vapour locking at high ambient temperatures.

3. The tendency of some pilots to skip pre-takeoff checks on busy days,

leading to running out of fuel.



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17It may be of interest to note that, statistically, the biggest risk to a glider piloton aerotow is not a broken rope or an outright failure of the engine, but thetug pilot allowing the engine to run out of fuel.

The possibility of an enhanced risk of engine failure should encourage tug-

pilots to have a sharpened awareness of emergency landing options on thetake-off path.

9.1.7 Minimum fuel for tow

Tug pilots must be acutely aware of the high rate of fuel consumption duringaerotowing, with the engine operating at full or very high power settingsduring the climb. A pilot used to a moderate fuel consumption at cruisesettings may need some time to become accustomed to this.

The problem is worsened by the poor design of some fuel gauges. Some

versions of the Pawnee, for example, have a fuel gauge which becomesopaque with age and almost impossible to read. There are similar traps inother tug aircraft, for example some taildraggers have fuel gauges whichdiffer markedly in their readings depending on whether the aircraft is in flightor in the tail-down attitude on the ground. Pilots should keep track of howmany tows they have done and refuel early rather than late. Trying to runthe tank down as dry as you can before refuelling, even in these days of nocompulsion to carry 45 minutes reserve fuel, is the very opposite of goodairmanship. On aircraft which have recording tachometers (most Americanmachines), keeping track of tacho time is a useful aid to fuel management.

Incredible as it may sound, there has been a case of a pilot taking offknowing the tug was short of fuel, but offering to tow a glider on the basisthat they might not reach the top of the tow. They didn't, and the result wasa completely unnecessary outlanding for the tug. This behaviour on the partof an experienced tug pilot was so stupid as to be almost beyond belief, butit happened. No marks to the glider pilot either. He should have told the tugpilot what to do with his almost empty tug.

9.1.8 Pre take-off checks

Normal pre take-off checks apply to tug aircraft. There is no reason not to

do such a check before every tow. There is ample evidence that manypilots do not do a satisfactory check before every take-off, as far more tugaircraft run out of fuel in flight than any other light aircraft. Before everyflight, make a habit of ensuring that you know the location of the tow-releaseand its direction of operation. You may need it in a hurry.

The repetitive nature of glider towing tends to result in skimped checks or nochecks at all. It might be thought that a pilot doing repeated tows hashis/her finger on the pulse and is in a good position to keep track of fuelstate, etc. The evidence suggests the opposite; that such pilots do in factbecome complacent and are more likely to get caught out than pilots who

are conscientious about checks on every flight.



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18A further thought is that fuel exhaustion often occurs shortly after a runningchange, where the replacement pilot has taken over an almost emptyaircraft, the "keeping track" chain is broken and the old pilot does not paythe new pilot the courtesy of mentioning the low fuel state. If the new pilotthen does not carry out a proper check, fuel exhaustion is inevitable.

The only answer to such problems is a proper check before each flight. Itmight seem like a nuisance, but the alternative is worse. During the checkturn on any external lights that will be useful for making you easier to see.

9.1.9 Ground signals

There are usually two signallers for aerotowing, one at the wingtip of theglider and the other positioned forward of the tug and to one side. Someclubs dispense with a forward signaller, but this is not a satisfactory practicebecause it forces the tug pilot to either look in the mirror or backwards over

the shoulder during the initial part of the take-off. Looking at the very smallimage in the mirror may cause the tug pilot to miss something which mightendanger the take-off; looking backwards is awkward and in any casecannot be done in some tugs because they have no visibility in thatdirection. It could also be argued, quite reasonably, that asking a pilot tolook backwards at all during a take-off is an unacceptable practice.

It is up to the tug pilot to accept or reject a take-off without a forwardsignaller. However, it is strongly recommended that the culture of a forwardsignaller be encouraged and tug pilots should ideally regard the lack of sucha signaller as a "no go" item for an aerotow take-off.

There are three signals from the ground crew to the tug pilot, as follows:-

9.1.9.1 Take up slack

This is an underarm wave signal given by the wingtip holder and repeatedby the forward signaller. The tug pilot should ignore a take up slack signalgiven by anyone else.

On receipt of this signal, the tug pilot should taxi the tug slowly forward untilthe slack is taken up. Taxying too fast runs the risk of jerking the glider

forward when the slack is taken up. If this occurs, there is a strongpossibility of the glider running over the rope, which may then wrap itselfaround some part of the glider's undercarriage or airframe. This is clearlyundesirable, so take it easy when taking up slack and keep your eye on themirror(s).

9.1.9.2 All out

This signal, known in some regions as "full power", consists of an overarmwave. It means that all the slack is out of the rope and the take-off shouldproceed. Again, the tug pilot should ignore an all out signal given by

anyone other than the wingtip holder or the forward signaller.



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199.1.9.3 Stop

Self-explanatory. This signal, consisting of one or both arms held stationaryabove the head, may be given by anyone at the launch point.

9.1.10 Take-off technique

When the "all out" signal has been given, open the throttle smoothly to fullpower, keeping in mind any "idle to full throttle, 2 seconds minimum"limitation that may apply.

At this point you will find that you have one additional job to do which younever had before. You should keep the forward signaller in view, even if it isjust in the corner of your eye, for as long as possible, just to make sure youdon't get a stop signal. If you do, there are specific actions to take, whichwill be covered under abnormal procedures.

Once you have full power applied, you will find that acceleration is muchless than you are used to. This is especially true if you are towing a gliderwith a nose skid, where the ground-drag is very high.

Keeping straight, even in a taildragger, is easier than it is without a glider onthe back during the initial stages. This is because of the pull of the rope.However, the pull of the rope also has a tendency to lift the tail of ataildragger. If you have cultivated a habit in non-towing operations of usinga lot of forward stick to lift the tail of the aircraft, you may find that you get abit of over-rotation at this point and will need to move the stick back a bit.

You are vulnerable if the rope breaks at this point, as the tail will be up, thestick forward and the tug will rotate smartly nose-down when the rope-breakoccurs. The correct technique when towing with a taildragger is to start thetake-off run with the stick aft of neutral, allowing the rope to level the tug,which it will naturally do as the take-off progresses.

Separation technique - gliders with light wing-loading

A glider with a light wing-loading (say between 20 and 30 kgs/sq. metre) willusually leave the ground before the tug. The pilot will position it a few feetabove the ground and do his/her best to hold that position until you lift off.You will find that you will have to make a positive rotation into the take-offattitude and the tug will then leave the ground and start its climb.

Some pilots then level off and let the speed build up to the full value they aregoing to use for the tow. This is not a good technique for this category ofglider, because it makes life unnecessarily hard for the glider pilot. The besttechnique for the average club glider is to let a bit of speed build up, thenlet the combination climb, even if you have not yet achieved the eventualclimb speed. You can then refine the nose attitude as you climb away, verygently accelerating to your full climb speed a few seconds later.



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20The advantage of doing it this way is that it does not overspeed the gliderand creates a bit of space under the combination, a real advantage for theglider pilot, especially if it is an instructional flight. There is no disadvantagefor the tug, because almost all the tugs have a take-off safety speed at orbelow the combination's climb speed.

There is a further advantage in letting the tug climb early in the take-off ifthere is a wind-gradient. If the tug is held down and then rotated into theclimb attitude after the full value of speed has built up, the attitude change isgreatly exaggerated by the increase in wind as height is gained. The tugpilot finds himself pulling back further and further and the glider pilot isbarely able to cope with the rapidly changing circumstances. This isillustrated in the diagram below, courtesy of Fred Foord of the AdelaideSoaring Club, who experienced the phenomenon at first hand andeloquently describes it, as he puts it, with a little help from Pythagoras.The climb angle, 36, is somewhat exaggerated, but serves to illustrate the

principle very well because it forms the hypotenuse of a 3:4:5 triangle.

The speed immediately after separation of both aircraft is assumed to be 61knots (the maximum aerotow speed of the Kingfisher the pilot was flying atthe time). When the tug climbs along the hypotenuse of the triangle, asillustrated, its speed over the ground falls to about 49 knots, a difference of11 knots. It will be apparent that if this occurs abruptly (which is whatoccurred), a slack rope is inevitable and the rope will probably break whenthe slack comes out. Either that, or the gliders nose will be pulled upuncontrollably. The glider-pilot has no choice but to release. Figures for theshortfall in speed at the tug end at other climb angles are - 2 knots at 15,

3.5 knots at 20, 5.7 knots at 25 and just over 8 knots at 30.

Separation technique - gliders with heavy wing-loading

When towing gliders with a heavy wing-loading (from 30 kgs/sq. metre to atypical value of over 50 kgs/sq. metre for a modern standard class glider fullof water), the opposite problem will occur. Heavy gliders may not leave theground before the tug - in fact it is reasonably common to see a heavy gliderstill on the ground with the tug airborne. If the tug climbs too early in thiscase, the glider will either not have flying speed and will have to releasebefore it collides with the upwind fence, or it may have marginal flying speed

and get dragged into the air barely above its stall speed and virtuallyuncontrollable. Neither of these options is attractive.



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21The solution is to keep the tug on or close to the ground until the knownclimb speed has been achieved, then allow the tug to separate and enter theinitial climb with plenty of speed to give the glider pilot good control. Amarginal speed for a heavy glider is really hazardous and can easily result inthe death or serious injury of the glider pilot in the event of a low-level rope-

break or the pilot having to release because of inability to control the glider.

From the foregoing descriptions of the two extremes of take-off technique, itbe obvious that the tug-pilot must know the characteristics of the gliderabout to be towed, especially its weight. Once this is known, the exacttechnique to be used may be pre-planned and put into practice. It isnecessary to go through this exercise prior to EVERY tow.

After separation and entering the initial climb, the glider will be initially in the"high-tow" position, just above the tug's slipstream. However, fairly early inthe climb, the glider will probably move down and settle in the "low-tow"

position below the slipstream. The tug pilot will feel the trim-changesoccurring as the glider changes position and will probably need to re-trim thetug when the glider has settled down.

The glider pilot may choose to remain in high tow throughout the entire tow.This will almost certainly be the case if the glider pilot is a visitor fromoverseas. Do not assume anything - wait to see which position the gliderpilot selects.

During the take-off, the tug-pilot needs to monitor options for any emergencythat may occur and choose a take-off path that takes these into account.

While abiding by the legal requirement to climb straight ahead to 500 feetAGL, the pilot may need to make slight deviations to maximise safety for thecombination during the take-off.

9.1.11 The steady climb

The primary reference for maintaining a steady climb is nose attitude. As ina glider, any tendency to over-concentrate on the airspeed indicator willresult in a wavering nose-attitude. This makes life very difficult for the gliderpilot.

The ASI should be used only as a trend monitor during the climb. Only if areasonably long-term trend indicates a deviation from the chosen climbspeed should the nose attitude be altered, and even then with care.

Care should be taken to ensure that the slip/skid ball is exactly in the middlewhen towing a glider. This not only optimises the climb rate (an aircraftflying sideways is not very efficient), but it makes it easier for a glider pilot toposition the glider accurately behind the tug. You would be surprised at howmad glider pilots get trying to line up on an aircraft which is flying slightlysideways through the air.

Make all turns gentle, especially with a training glider on the back. Noinstructor will thank you for steep turns on tow.



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22Do not assume that the glider pilot you are towing is very skilled. Everybodyhas to learn, and quite a high proportion of glider tows are training flights.Be prepared to work hard to maintain a steady platform for the glider while itswings around on the back trying to hold position - this is where doing sometows at the glider end yourself gives you some empathy with the glider

pilots problems.

Carefully monitor engine instruments when aerotowing, especially oiltemperature, oil pressure and (if fitted) cylinder-head temperature. If cowl-flaps are fitted, it may be necessary to adjust these during the climb,although they will usually be left fully open. Unless the engine has a timelimitation on full power, the throttle is usually left fully open on the climb.

The mixture should not be weakened unless density altitude problems causerough running.

Do not climb on a constant heading for long periods of time. All tug aircrafthave blind spots and it is essential to ensure that the airspace you are aboutto occupy is clear. Remember that targets which are stationary in thewindscreen constitute the biggest collision risk and perversely are the mostdifficult to detect. You will need to find a sensible compromise between agood search pattern to eliminate stationary targets as much as possible,while still retaining a good steady platform that a trainee glider-pilot will beable to follow without undue difficulty.

As a general principle, tow into wind. A glider's range if towed downwind is,for the purpose of returning to the airfield, only one-third of its range if you

towed it into wind. Only tow downwind (or a long way crosswind) if you areasked to, or if controlled airspace or other reasons compel you to.

If cumulus clouds are present, read the sky and plan on maximum use of liftduring the climb. When descending, plan on using the sink to assist thedescent. If it is a blue day, with no clouds, work out as soon as you canwhere the lift is, and use it to maximum effect during the climb. Ditto withsink for the descent.

Avoid rain and close proximity to cloud. Gaggling gliders can betroublesome, but in competitions is an occupational hazard. When towing in

competitions, exercise extreme care near gaggling gliders.

Monitor the mirror(s). The ideal mirror installation for a tug is either onelarge panoramic, slightly convex mirror which covers both high and lowtowing positions (at the expense of rather high drag), or two smaller mirrors,one aimed at high tow, the other at low tow. These should preferably beadjustable from inside the cockpit.

9.1.12 High-tow and low-tow

An aircraft in flight generates a slipstream behind it. This is a region of

turbulent air, originating mainly from large vortices streaming from the



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23wingtips, with small amounts of other turbulence such as propeller washthrown in for good measure.

A glider pilot may choose to fly either above or below this turbulentslipstream. As already mentioned, Australia tends to favour the low-towposition. Other countries prefer high-tow.

Low-tow

With a glider in low-tow, below the slipstream, the combination tends to be alittle more stable and tug pilots have less difficulty in maintaining a steadyplatform for the glider pilot to follow.

High-tow



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24In high-tow, above the slipstream, the combination feels a little more livelyas far as fore-and-aft trim is concerned and tug pilots need to concentrate alittle harder. The difference is not large and tug pilots should have nodifficulty in maintaining a steady platform whichever position the glider pilotchooses. Note that high-tow is, by definition, above the slipstream, not

above the tug.

There is one important difference between low-tow and high-tow and thisbecomes apparent if a glider gets out of position vertically. In low-tow aglider can get very low and still not cause great difficulty for the tug pilot incontrolling his aircraft. Furthermore, out-of-trim forces tend to change at aslow enough pace that the tug pilot has ample time to release the glider ifthere is any fear that the limits of control might be reached.

In high-tow, things happen more rapidly and the tug pilot will have to reactrather more quickly to a glider going too high. If an excessively high glider is

not released without undue delay, there is a risk of being pulled out ofcontrol. See Section 9.3 The tug upset.

Tug pilots need to be trained to tow gliders in both high and low-tow and toexperience a glider transitioning between the two positions. To avoidsubjective judgements about high-tow and low-tow, the reference forestablishing towing position is always the SLIPSTREAM.

9.1.13 Boxing the slipstream

Glider pilots sometimes carry out an exercise known as boxing the

slipstream. It is a good test of a glider pilots aerotowing skill and theexercise is carried out by flying the glider in a box pattern around theslipstream, initially moving to the right, still in low-tow, then moving up intohigh-tow, still out to the right. The glider then slowly crosses from right toleft in the high-tow position, then descends to the low-tow position while stillout to the left. Finally the glider returns to line-astern in the low-tow positionand the exercise is over.

The objective is for the glider to carry out this exercise without contacting theslipstream and the tug-pilots job is to maintain a constant attitude andheading during this exercise. This means constantly changing control inputs

as the glider changes position. Some of these control inputs may be quitelarge. The most critical point is the transition from right to left in high-tow,where a glider pilot sometimes moves too quickly and gets a lot of slack inthe rope. This may or may not be a problem, depending on where the ropegoes in its travels!

As in all phases of an aerotow, if you feel you are being taken close to thelimits of control or you have no idea where the glider has gone, get rid of it.Do this BEFORE you lose control altogether.



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259.1.14 Releasing from tow

Ensure the rope has released before beginning descent. Do not begindescent until you have CONFIRMED VISUALLY that the rope has beenreleased from the glider. If the mirrors are not adequate for this purpose,

you must turn round in the seat to make sure it is clear. NEVER assumethat a jerk or twang in the rope is the glider releasing and NEVER rely on aradio call, especially if it is a blind (no callsign) call.

9.1.15 The descent

When certain that the glider has gone and that the airspace you are about tooccupy is clear, begin the descent. Dont fiddle around maintaining almostlevel flight while you gingerly reduce power - you will take all day to getdown. Start closing the throttle smoothly and get the aircraft descending.Use carby heat as required. Be careful not to accelerate too quickly in the

early stages of the descent. Interchange throttle closure with airspeed toachieve a moderate initial descent rate, keeping in mind that too muchspeed is a bigger factor in cylinder cracking than closing the throttle too far.Keep all throttle movements smooth and power reductions gradual.

Note that, although the glider will always turn to its right after release, thereis no need for the tug to turn immediately. Clear the aircrafts blind spotsbefore manoeuvring. Once again, remember the stationary targetproblem.

NO AEROBATIC DEPARTURES AFTER RELEASE. Any pilot who

indulges in these antics is a hazard to everyone else in the vicinity and suchbehaviour will usually result in a club showing the pilot the door.

Plan the descent profile, using any sink you can find, regularly clearing theaircrafts blind spots, avoiding other traffic and generally not making anuisance of yourself. Remember the rope!

Do a head-count of known traffic during the descent. Make maximum useof aircraft shadows to locate them. However, even when you are certainyou have accounted for all known traffic, do not relax. There may be visitingaircraft or gliders and it is well-known that its the one you dont see that gets

you! Know your airfield procedures, especially if you are in a CTAF orCTAF, operate in accordance with them and remember that you arelegally obliged to give way to gliders. At circuit entry, make any applicableradio calls. As a general principle, be where other airspace users will expectyou to be.

If you know there is a glider there, but you cant see it, there is a school ofthought which recommends placing the tug in a position where a glidercannot normally go - low and a long way away. If you do this, you may beable to pick out the missing glider against the sky. However, your ownaircraft will not be as easy to see and you will probably violate the principle

of being where you are expected to be.



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26Continue monitoring the engine during the descent, planning to be at yourapproach power settings by the time you are on base leg. Aim to enter baseleg not lower than 500 feet AGL. Do not cut gliders off, remember they haveno engine to re-position themselves. Do not cut off any other powered trafficcommitted to landing. Take account of any built-up areas.

Carry out pre-landing checks, being especially meticulous about fuel.

9.1.16 Landing

Enter base leg and final. Keep clearing the aircrafts blind-spots. If youhave been using carby heat, select cold air on final approach in preparationfor a possible go-around. Open the cowl-flaps for the same reason.Remember the rope and give yourself plenty of clearance over obstacles.Approach high and land long in preference to cutting it fine over people orobjects on the ground. A 55 metre rope hangs about 40 feet below a tug at

approach speeds. NEVER land over the top of parked gliders. Rememberthat tugs have no exemption from the requirement to have the wingslevel on a stabilised final approach for a minimum distance of 500metres.

Most tugs carry out glide or near-glide approaches. A particular hazardassociated with this practice is the possibility of descending on top ofanother aircraft or glider which has remained in the tug pilots blind spotthroughout the approach. A number of collisions and near-collisions haveoccurred from this cause. Check very carefully during the final turn that youare not about to become involved in one of these conflicts, again making

maximum use of all cues available to you. Shadows are especially effectiveand valuable at low level. Remember that, even if you do avoid a collisionby last-minute evasive action, your rope is still a hazard.

9.1.17 Baulked approaches and go-arounds

On every approach, be prepared to go around. You never know whensomeone will walk, or even drive, out in front of you to retrieve a parkedglider. Remember the rope!

9.1.18 If in doubt, drop the rope

When the rope is dropped, it loses forward impetus very quickly and ends updropping almost vertically to the ground. In any case, even if it still hassome forward motion, it will probably not do a great deal of harm as long asit is not still attached to the tug aircraft. If you have any doubt aboutobstacle clearance, whether it be buildings, vehicles, parked or taxyingaircraft or people (especially people), dont hesitate to drop the rope. It isinexcusable, and may prove fatal, to drag a rope through a gathering ofpeople.

The same applies to a go-around. Much better to drop the rope and

eliminate that particular worry than to risk hitting something underneath yourprojected overshoot path.



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279.1.19 Approaching too low

Hitting the fence with the rope is unfortunately very common, usuallyresulting in loss of the rings. This in turn usually results in you being invitedto lead an emu bob to find them. Occasional genuine misjudgements do

occur, but many cases of hitting fences with ropes are the result of pilotsdeliberately cutting things too fine over the fence in an attempt to land asshort as possible to reduce the need for taxying.

You need to ask yourself whether such a technique is really worth-while.Hitting a fence with the rope is one thing; hitting someone who is standingnear the fence, or a vehicle on a road, is inexcusable.

It is much better to accept the need to taxi back to the launch point eachtime than to cut things finer and finer until eventually a completelyunnecessary accident occurs and somebody gets hurt.

9.1.20 Cruising on tow

Most glider towing consists of a climb, dropping the glider, then a descent.Occasionally there will be a need to actually cruise the combination in levelflight. This may occur during an aerotow ferry flight or in the training forsuch a flight. The gliders maximum aerotow speed is essential informationfor the tug-pilot to have before take-off.

The presence of a glider on the back makes quite a difference to thetechnique you will need to use in certain parts of the flight. For example the

usual APT (Attitude, Power, Trim) technique for transitioning from climb tocruise may be used, but if so, it must be smoothed out and spread over amuch longer time than usual. Otherwise you will risk getting a lot of slack inthe rope and may even break it.

A better technique in this phase of flight is to start reducing power, still in theclimb attitude, as you approach your cruise altitude. Know your aircraft,especially its power/weight ratio, and fly it in such a way that you startreducing power while still in the climb. The rate of climb falls off and thenose should be very gently lowered to keep the speed virtually constant asthe power is reduced. As the climb-rate approaches zero, the nose should

be at or very close to the cruise attitude and the speed will build up veryslowly. It wont get away from you, because the power has already beenreduced. The attitude change and rate of speed-change during thismanoeuvre will be gradual enough for the glider pilot to adapt to bothwithout getting a lot of slack in the rope. When you are established in levelflight and have refined the power setting to get the cruise speed you want,trim the aircraft out.

When established in the cruise, with the glider settled in its towing position, itwill feel different from the climb. The drag of a modern single-seat glider isvery low, in the order of 15 to 25 kgs in level flights at 70 knots or so, and

this does not provide much pull on the rope. This is not a problem ifconditions are smooth and the glider pilot is competent. However, it can be



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28a different story when conditions are turbulent and/or the glider pilot is a bitbehind the eight-ball.

In cruise flight do not relax. Monitor the mirrors continuously andconcentrate on accurate attitude control. You can expect the occasional tail-

wag, as a bit of slack develops in the rope and the glider pilot takes action tocorrect it. This will be virtually constant if the air is rough. As is the case inany other phase of aerotow operations, if the antics of the glider on the backare taking you to the limits of control, you are entitled to get rid of it.

During cruise flight, especially if the air is rough, the glider pilot may find itnecessary to use small amounts of airbrake to keep the rope tight. This willprobably not be a permanent condition, but it may occur at intervals duringthe flight. Unlike normal aerotow launching, this is quite normal and youshould not worry about it.

Also unlike ordinary aerotow launching, the glider pilot on a ferry flight willnot thank you for seeking out thermals. Try to find the smoothest air youcan, in the interests of comfort and safety. If you think it is hard controllingthe tug when cruising in rough air, try it on the other end of the ropesometime!

9.1.21 Descending on tow

This is not normally required on a ferry flight, as the glider will usuallyrelease and make its own way into the circuit, leaving the tug to do thesame. However, a descent on tow may be required from time to time, for

example to remain outside of controlled airspace. It is also a post-solotraining requirement for glider-pilots.

When transitioning from cruise flight into a descent, the normal APTprinciple does not work at all. If the nose is lowered with cruise power stillapplied, the speed gets rapidly out of hand and this makes things impossiblefor the glider pilot. Once again start reducing power very gently at aconstant attitude, then allow the nose to fall slowly so that the descentdevelops slowly without a great build-up of speed. Refine your power-setting and nose attitude as the descent settles down, monitoring the mirrorsfor the glider pilots well-being. Trim when ready

It is almost impossible to start a descent without getting some slack in therope, especially in rough air. You can be sure that the glider pilot will bemonitoring this as closely as you, and the gliders airbrakes will almostcertainly be used to keep this under control. Watch the glider carefully inyour mirrors and if it needs to use full airbrake to keep the rope tight,moderate your descent until the airbrakes retract a little. You now know thatthe glider pilot has a little more drag up his sleeve if he should need it.Continue the descent in this fashion until the glider releases.



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299.1.22 The Non-Manoeuvring Area (NMA)

Under certain circumstances, such as a low-powered tug towing a glider offa fairly short strip in a light wind, it is possible to get into a situation where, ifthe rope should break or the tug wave the glider off, the glider would be too

high to land ahead within the available strip and too low to safely turn backto the strip. This is known as the Non-Manoeuvring Area (NMA).

The NMA does not apply directly to tugs, as all power pilots know thatengine failure is possible at any time and they plan their options accordingly.These options are often not very attractive and it is true to say that any pilotoperating out of a capital city GAAP aerodrome effectively spends quite a lotof time in an NMA. However we now have a glider to consider and theeffect of an NMA on a tug-pilot is to focus attention on the gliders situation.

If a rope should break, for example, the tug is completely unaffected. It is a

different story for the glider. The tug pilot should plan the take-off path suchthat, even though the glider may be in a non-manoeuvring area, the bestpossible options are available to it, preferably a straightforward outlanding ina paddock. If this is not possible, at least track over such terrain that theglider will be able to achieve a survivable landing, even though it might bedamaged. This is a new concept for a power pilot and is a good example ofthe effect of having to think for two people at the same time. It is the tug-pilots duty to do the best thing by the glider pilot at all times, at the sametime not compromising his/her own safety.

9.1.23 Some suggested towing patterns

The towing patterns suggested here, courtesy of the Waikerie Gliding Clubstowing notes, are just a few of many possible variations. If the wind is verylight, the tug may circle, but the combination should never be takendownwind of the mid-point of the strip, except by request of the glider-pilot.In strong winds it may be possible with some tugs to tow straight upwindwithout making any turns except clearing turns to compensate for aircraftblind spots.

At all times, keep a sharp lookout, continually clear the aircrafts blind spotsand if possible avoid those parts of the sky in which you know traffic will

congregate, e.g. circuit joining areas.



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30ABNORMAL PROCEDURES

Practical coverage of items 9.2.1 to 9.2.7 is mandatory. Item 9.2.8 isoptional.

9.2.1 Stop signal during take-off run

9.2.1.1 Early in the take-off run

Release glider. Monitor mirrors and be acutely aware of possibility of gliderrunning into the back of the tug. Keep the tug moving, avoiding suddenbraking.

There is no particular reason to turn after you have released the glider, atleast until you are sure the glider has stopped. Get well clear, THEN turn.

9.2.1.2 Later in the take-off run

Release glider. If you have a fair bit of speed on, it is probably better tocontinue your take-off and thereby ensure that you are well out of thegliders way. Carry out a short circuit and try again.

At all times think ahead, assume you are going to get a stop signal on eachand every take-off and be prepared for it.

9.2.2 Engine failure

the gliding federation of australia

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