Managing Flying Risk – Towing / Operating Tug Aircraft

Terminology

  • ‘Aeroplanes’ are powered aircraft that are not sailplanes
  • ‘Aircraft’ includes both aeroplanes and sailplanes
  • ‘ANO’ is the Air Navigation Order as amended
  • ‘TMG’ is a Touring Motor Gliding (eg a Scheibe Falke)

Introduction

These notes are intended as a general, high level guide to glider towing operations and have been compiled in the interest of safety, efficiency and compliance with law. They include good practice examples that have been developed over many years of successful towing operations at BGA clubs. The BGA accepts no responsibility for any of the suggested practices contained in this guidance. Each club has its operating environment and challenges and should adapt the suggested practices to suit their own needs.

Each tug pilot carries a degree of responsibility. Aerotowing is potentially expensive, can create noise and has hazards associated with it. These factors have a bearing on the very existence of gliding. It is therefore essential that aerotowing is carried out safely, efficiently and thoughtfully, paying particular regard to our neighbours.

Ultimately, a tug pilot is responsible for the safe conduct of the flight and the actions that they choose to take while accommodating the glider pilot’s requirements as far as possible.

The tugging operation exists of course to provide launches to gliders. Waiting time should be minimised and the launch needs of the glider pilot met. For example, solo soaring pilots may require you to drop them in the nearest lift source, whilst students may need to remain near the field with gentle manoeuvres.

Another important point is to minimise cost to the club by conserving the engine, by careful handling and reducing fuel burn, by accurate aircraft handling, and by minimising ground running.

In short. the three main points that a tug pilot should always aim to achieve are:

SAFETY – Safe flying and good airmanship is expected at all times and is everyone’s responsibility.

ACCURACY – Delivering the best service to the glider pilot.

EFFICIENCY – Handling the engine with precision, being economical with fuel, and ensuring efficient turnarounds

Detailed Guidance

This publication provides guidance for tug pilots and operating clubs.

The BGA publishes safe aerotowing advice aimed at glider pilots – all pilots who aerotow should read and absorb this important safety information.

Pilot Licensing Requirements

The required pilot licence privileges depend on the type of tug aircraft.

Part 21 single engine piston tug aircraft require a pilot licence with SEP privileges (see Part-FCL), or if a TMG, TMG privileges (see Part-SFCL).

Non-Part 21 single engine piston tug aircraft require a licence with SSEA (see ANO Schedule 8) or SEP privileges, or if an SLMG, SLMG (see ANO Schedule 8) or TMG privileges.

Microlight aircraft require a licence with microlight privileges. For a PPL(A) or LAPL(A) holder with SEP privileges, the licensing requirement is microlight differences training signed in the pilots logbook. For an NPPL holder with SSEA privileges, the licensing requirement is to add a microlight class rating via a technical theoretical knowledge exam and a skills test. Sailplane towing training can be carried out in a factory built Eurofox providing the instructor and student pilot both hold microlight privileges. Our colleagues at the BMAA have published this helpful guidance.

Recency requirements for a LAPL(A) are described at FCL.140.A LAPL(A) — Recency requirements. To maintain LAPL(A)/PPL(A) towing recency, refer to FCL.805 (e), ie min 5 tows in the previous 2 years.

Recency requirements for an SPL are described at SFCL.160 – Recency Requirements. To maintain SPL TMG towing recency, refer to SFCL.205 (f), ie min 5 tows in the previous 2 years.

All tug pilots are strongly advised to monitor their recency, date of last refresher flight, and to regularly check the validity of their licence and associated privileges. Failure to do so can result in operating illegally, and in the event of an accident and insurance claim, the pilot may become liable.

Tug Pilot Training

Most clubs require their tug pilots to be glider pilots – the reason should be obvious.

The BGA recommends the BGA DTO Sailplane Towing Course Programme.

Sailplane towing rating training can take place in a microlight aircraft where the instructor and licensed pilot under training both hold privileges to fly microlights, including privileges obtained through differences training signed in the pilots logbooks.

The BGA DTO Sailplane Towing Course Programme is also recommended as a guide for training tug pilots who do not legally require a towing rating. The BGA senior tug pilot can be contacted for guidance.

Transitioning from ‘newly trained tug pilot’ to a ‘club approved tug pilot’

Once qualified, the new towing pilot should be briefed in detail by the club tug master ahead of local standardization including, possibly, a type conversion. This is a very important aspect of a tug pilot’s development as there will be a number of local hazards that must be taken into consideration and mitigated by following local operating procedures. Once up to speed with club procedures, new tug pilots are usually monitored closely by the club tugmaster. After all, the tug is probably one of the clubs most expensive and difficult to replace assets!

Operations Rules

Part 21 tug aeroplanes are subject to Part-NCO rules*. Part 21 TMG tugs are subject to Part-SAO rules. Non-Part 21 tugs are subject to the ANO. There are links to the rules on our Laws and Rules webpage.

Under Part NCO, Part SAO, and the UK ANO, “sailplane towing performed by an organisation created with the aim of promoting aerial sport or leisure aviation, on the condition that the aircraft is operated by the organisation on the basis of ownership or dry lease, that the flight does not generate profits distributed outside of the organisation, and that whenever non-members of the organisation are involved, such flights represent only a marginal activity of the organisation” (in other words, a gliding club) is not commercial activity.

Clubs should additionally have in place club towing operating procedures that reference the law and local requirements or restrictions.

*Under Part-NCO, aerotowing is an NCO-SPECialised operation that needs to be risk assessed.  There is a compliant template risk assessment available here.

Club Tugmaster

The club chief tug pilot or tugmaster is, in conjunction with the club CFI and the club tug pilots, responsible for safe and efficient operation of the tug aircraft. He or she should be as knowledgeable as possible about gliding and light aircraft operations and should ideally have a direct link to the club’s management committee. Advice for tug masters and tug pilots is readily available from the BGA chief tug pilot (contact via the BGA office). Some large and established gliding clubs have particularly experienced tug masters and would be pleased to pass on advice or help in any way. Any pilots or club officials are encouraged to ask for advice or simply exchange ideas, especially anything safety related.

Tug pilots must maintain pilot licence and rating validity in accordance with the relevant regulations. Instruction associated with a licence or a towing rating may only be provided by an FI or CRI with the required aircraft class rating, towing privileges and experience. The tugmaster is ideally placed to co-ordinate this type of activity alongside the CFI.

Standardisation flights where the tug pilot is PIC and the tug master as passenger observes the actions of the tug pilot are not instructional flights.

Tugmasters don’t need to be an FI or CRI.

Monitoring Tug Pilots Compliance with Licensing and Medical Requirements

Having an insurance claim turned down because the pilot involved is not compliant with licensing and medical rules could be financially challenging for an individual or club.

Clearly it is the responsibility of an individual tug pilot to comply with licensing, medical and recency requirements. At some clubs, the tugmaster supervises this important aspect of tug pilot administration (and club governance) by monitoring tug pilots relevant due dates.

A simple spreadsheet with the pilots licensing details on it including next check due and date of medical expiry that is regularly checked by the tug master and any subsequent issues raised directly with pilots can be very helpful.

Recency and Standardisation

Recency and checks in addition to that required by law are at the discretion of the club tug master and can also depend on the individual pilots experience.

Anyone who has not flown within a reasonable period of time should fly a standardization trip in that aircraft before towing. This should be done with the tug master or qualified instructor if possible. Note that 3 landings within 90 days are legal requirements when carrying passengers.

It is suggested that each tug pilot should occasionally have a standardization flight with the club tug master or a suitable FI or CRI to include normal tows, general handling and emergency drills. The flight should be viewed as an opportunity to practice flying skills and practice unusual situations with a ‘friendly critical’ observer.

Noise

Continual towing or descent over the same area may cause nuisance and irritation to our neighbours. Some tugs have already been modified to minimise the actual noise produced. However, the load can be spread by thoughtful and varied tow-out patterns. Variation therefore should be part of club developed noise abatement procedures.

Remember that the noise of a descending tug with a relatively high power setting can be annoying, so apply the same noise abatement techniques and practices during the descent. Also try and make your descent route different from the tow-out route.

Logging Flying

All aircraft movements need to be recorded. Most clubs use an aerotowing log in the aircraft. All aero-tow retrieves, positioning flights or hire flights should be entered. Particular attention should be paid to overdue procedures and the reporting of any defects. The log sheets are an important part of the clubs financial record keeping – accuracy is key including names, membership numbers, tow heights and engine time used. The person who has to use the data will be delighted if they can read the handwriting! However, don’t let the paperwork detract from safely operating the aircraft; it’s important to carefully manage cockpit tasks.

Lookout and EC

The BGA encourages the widespread use of traffic and collision warning systems in gliders, motor gliders and tugs. Many tug aircraft are equipped with FLARM which supports tug pilot lookout in the busy environment near the airfield.

Pilot Health

It might be stating the obvious, but ensure that you are fit to fly. If flying under a canopy, wear a hat. If flying for a period of time take a bottle of water to remain hydrated and consider taking a snack. Don’t let any of these items become loose articles and jam your controls! Tiredness can creep up on a pilot. Regular breaks from towing duty on busy days is important, and a club policy on recommended towing duty time can help pilots make the right decisions.

Deciding enough is enough

It is the tug pilot’s responsibility, after full consultation with the person in charge, to terminate aero-tow operations if the tug pilot is not happy to continue, eg because conditions are unsuitable (eg weather, light, etc). Tug pilots must resist all forms of persuasion to launch if they do not want to. Remember, however senior the pilot of the glider the tug pilot is commander for the whole combination until release.  Where possible, its helpful to give the glider pilots/the instructor in charge advance warning of an intention to stop towing. Avoid towing in extreme weather conditions, eg thunderstorms, heavy showers, etc or where the weather causes the aircraft handling in the air or on the ground to become unreasonably difficult.  And please be reasonable – listening to and considering advice from other more experienced pilots is all part of the learning process.

Winch Cables

Cables in the air or on the ground are particularly dangerous. With cables laid on or near the runway,it is essential that a takeoff by a powered aircraft should only be undertaken when the positions of the cables are known to the pilot and the take-off run can remain well clear of the cables. If its not possible for the pilot to make a visual check, a radio call is suggested to confirm this with the glider launch point. Delay the launch until the cable is clear of the planned takeoff run. Do not take off across or close to winch cables.

An AAIB report into a fatal accident resulting from an aircraft attempting to take-off having picked up a winch cable is available here.

Tow Rope Clearance

Ensure adequate clearance of the towrope from the ground when approaching to land and in general do not over fly people, cables, aircraft or vehicles prior to landing. Leave a reasonable amount of height approaching over crop or any boundary.

Fuel

No tug aircraft should take off unless the pilot in command is certain there is sufficient fuel in the tanks for safe operation. There are legal limits for minimum fuel defined in Part-NCO and the ANO. If in any doubt, refuel!

Fuel starvation is still the most common cause of engine failures in piston singles but it is also the most avoidable. It is imperative that you do not allow yourself to be pressured into carrying out ‘just one more tow’ when you think you should be refuelling.  Prior to takeoff, always know how much fuel you have remaining. As always, think ahead to help keep the operation safe and efficient. For example, is the next tow a spin training exercise to altitude, necessitating more fuel? Or, there will be a natural break after the next launch where the time can be used to refuel.

If your club operates a tug aircraft where assessing fuel content before take-off is very difficult to achieve, seek technical advice from an expert. And please make sure the fuel you take on board is of suitable quality, eg suitable for the aircraft and free of water, etc.

Don’t live with a potentially lethal issue hoping nothing will go wrong. If it can go wrong, it will.

Ground handling of fuel needs care too. There is a useful CAA safety leaflet here.

Tail Wheel Tips

Here are a few tailwheel tips. In all cases, the Aircraft Flight Manual should be referred to paying particular attention to any wind and cross-wind limitations.

The dynamics of a nose-over

Aircraft with a tailwheel have nothing to stop them nosing over except the propeller.  The C of G of a tug aircraft is somewhere above and behind the mainwheels. As the tail rises (eg at the start of a nose-over), the C of G is rotated forwards towards the axle line and the natural tendency for the aircraft to sit on its tail (gravity) quickly reduces.  Once the tail starts to rise, the force which is causing it to rise has a progressively easier job and it will accelerate into a nose-over resulting in a bent prop and a shock loaded engine.

The following factors contribute to a nose-over

Using power against brakes.  The thrust line is above the axle line. Any power against one or both brakes may try to pitch the aircraft forward over the wheels. The same effect can occur on soft ground.

Elevator control position.  The elevator is an effective control on the ground. With all 3 points in contact with the ground, the stick should be held fully back.  With any wind or slipstream blowing over the tailplane, this stick position provides a powerful download on the tail in addition to gravity.  Landing roll outs and taxiing into wind without full back stick may lend themselves to nose-over.  Taxiing with a tailwind component should be carried out with the elevator neutral or down. That way the tailwind will provide a little more download on the top surface of the tailplane/elevator. In aircraft with a trim tab, the trim tab can be positioned to add to the effect.

The elevator trim position needs care. In some aircraft, elevator loads on the ground vary with trim setting and can result in less actual control authority than perceived by the pilot.

Aileron control position. With the wind on the nose either straight on or from an angle on the ground, the ailerons should of course be used conventionally to help to maintain wings level. Once any crosswind also becomes a tailwind, the upwind aileron should be lowered. That way the tailwind will provide a little more download on the top surface of the aileron to help to counter any upload from the crosswind.

Propeller effects.  Power-on torque drives the propeller in one direction and tries to roll the fuselage the opposite way.  This pushes one wheel hard into the ground, ground friction is increased (especially on soft ground) and the aircraft yaws towards that wheel.  The propeller’s gyroscopic and aerodynamic forces can complicate the process further.

Taxiing.  Great care must be taken when taxiing in strong winds, particularly when operating off grass when more power is needed to taxi.  If the aircraft will not turn with the brakes correctly set, it can be tempting to keep adding power to force the aircraft to turn. A safer option is to use a wing holder/walker to assist. This minimises the use of power against a braking force, which features in almost all tailwheel nose-over incidents. Other extra weight, eg a fixed ballast weight on the back seat of a tandem aircraft can help to increase the tail load.

Changing conditions. Staying aware of the evolving situation is important. Nose-over accidents have occurred as the tug was slowing to a stand still side-on to the wind. Strong gusts can easily give a side wind a strong head or tail component, therefore it is likely to be safer to halt or park facing into wind.

If the wind becomes very strong or very gusty and as a result taxiing is difficult, shut down with the aircraft pointing into wind and manhandle the aircraft back to the launch point or retrieve it with its tow rope.  In both cases, keep the aircraft’s nose pointing as near to the wind as possible and keep the pilot in the cockpit. Restart only when  pointing into wind. Be assertive as the tug pilot – only continue towing if satisfied it is safe to do so. Consider asking for the launch point to be moved forward if safe to do so.

Keeping propellers, vehicles and people apart

Clubs should ensure that they put in place protocols that keep rotating propellers, people and vehicles apart at all times. Having notified car parking areas helps along with established tug parking areas and taxiing routes.

Pilots of tail dragger tugs are politely reminded to ‘get weaving’, ie when taxiing, weave the tail from side to side to ensure the view ahead and under the nose is clear.

Lighter Tugs

Lighter tugs are potentially more susceptible to tug upsets than heavier aircraft. Clubs that have lightweight tugs should ensure that their instructors and pilots are aware that flying out of position on tow should be limited to a smaller letterbox than may be appropriate for a heavier tug. For example, limiting horizontal out of position to the tugs wingtip.

Lighter tugs are more susceptible to strong surface winds and gusts. Particular care is needed when taxiing and parking in strong winds.

Some lighter tugs may have a shallower climb angle than others. Tug pilots should take into more careful consideration related issues such as a safe climb out route for the tug, the same for the glider on tow in the event of a rope failure, and noise.

Daily Inspection

The Tug Pilot should conduct a daily inspection (DI) of the tug. Any defects must be brought to the attention of the tug master and duty instructor immediately so that they can be rectified at the earliest opportunity. If necessary, ensure that an unserviceable tug is not used later by someone who is unaware. If unsure about how to carry out a daily (pre-flight) inspection, refer to the Pilot Operating Handbook.

The tug pilot should also DI the rope, checking for chafing, knots, reduced length due to repairs and the condition of the rings and weak links. Generally, the longer the rope the safer it is for the tug pilot. However, in practical terms 180 feet is a reasonable compromise. Unserviceable ropes should be identified and put in a place where they cannot be inadvertently used. Please do not attempt to repair a broken rope or change a broken weak link unless you know what you are doing.

Ensure that there is a suitable weak link assembly located at the tug end of the rope. Some clubs fit a weak link at both ends. BGA Operational Regulations state;

“Weak Links – Aerotow. An aerotow rope or weak link, if fitted, shall have a strength not exceeding the lesser of the maximum breaking load determined by the body responsible for certification of the tug aircraft and the maximum breaking load approved by the body responsible for certification of the glider.”

Maintenance

All tug aircraft maintenance should be carefully managed including use of an appropriate maintenance programme, eg Self Declared Maintenance Programme for Part 21 aircraft or an LAA maintenance programme for a non-Part 21 Permit tug managed under their airworthiness system, or similar under the BMAA system. Tug-masters should note that pilot owner maintenance tasks are defined. It may be appropriate for the club to approve specific tug pilots to carry out approved pilot owner maintenance tasks on the club tug aircraft. If in doubt, seek advice.

Lightweight and fuel efficient tug aircraft are growing in numbers. It is likely that their lighter airframes and modern lightweight engines mean that these aircraft need a more proactive approach to preventative maintenance than ‘legacy’ tug aircraft.

Propeller Swinging

Propeller swinging can be very dangerous. Avoid doing it if possible! If the aircraft simply has a flat battery, consider charging it or jump starting the machine. If swinging is carried out it should be done with great caution. A few general safety precautions could include:

  • Always treat a propeller as live
  • Ensure the aircraft brakes are set
  • Ensure the mixture is at ICO (Idle Cut Off)
  • Ensure the mags are off
  • Ensure the throttle is closed
  • Use chocks
  • Ensure that there is a competent person in the cockpit
  • Ensure that the area around the propeller is clear of oil, water and anything that could cause you to slip
  • Establish clear communications
  • Never hand swing an aircraft with a 4 blade propeller . 4-blade propellers are lighter as they are made of wood and have less inertia to carry through the compression, usually smaller in diameter so more force is required and the next blade comes around in half the time.

If in doubt, don’t.

Considerations Before Take-off

In addition to the normal considerations prior to take-off, a tug pilot needs to think about the combination of a tug and glider. Radio contact with the glider and launch point can be very helpful for everyone’s situational awareness.

Think about the climb performance. Part-NCO rules require a risk assessment and climb performance is part of that. There’s detailed advice on aerotow performance here.

Think about the glider and glider pilot and consider;

  • Tow hook position
  • Low-experience pilot
  • Short tow rope
  • All flying tailplane
  • Lightweight glider pilot that might cause a rearward centre of gravity
  • Turbulence and windshear
  • Cross or slight tail wind

A rule of thumb is that if you have three of these items, consider not launching that glider!

Be very aware of winch cables laid out on the field and winch cables still in the air.

Think about a go / no-go point for the takeoff run and have a plan for that eventuality.

BGA Lead Tug Pilot

The BGA volunteer lead tug pilot can be contacted via the BGA office.