By Paul Reynolds  

Attaining a gliding aerotow endorsement provides a gateway to a new world of experiences and challenges. Paul Reynolds explains.

Firstly, the endorsement introduces you to the gliding community, a group of people who generally look at weather conditions differently from their powered cousins. Secondly, it opens your eyes to a mindset of staying aloft without man-made assistance - some pilots regularly achieve glider flights of up to eight hours. Thirdly, being rostered as a ‘tug’ pilot at a gliding club provides extremely challenging flying where glider pilots rely on your flying skills and interpretations of weather formations to position them in the best place to release from tow; and to maximise their opportunities to remain aloft.

However, getting to this point requires the convergence of a disparate set of skills and experience, and a healthy dose of determination. The major technical skills required are the ability to fly a tail-dragger and to have some aerotowing experience in a glider; plus demonstrating to the relevant people the appropriate temperament needed to become a reliable member of a gliding club’s towpilot roster. 

As the majority of the aircraft used for aerotowing in Australia are Piper Pawnees, CallAir or Piper Cubs, tail-dragging experience is a must. However, simply having a ‘fresh’ tailwheel endorsement is generally not enough. Due to the very busy aerotowing environment, operating the aircraft has to be second nature so you can concentrate on delivering a safe and efficient service to your glider pilot ‘customers’.

Before undertaking the aerotow endorsement, I accumulated approximately 60 hours as pilot-in-command in taildraggers, which helped me cope with the requirements to master the nuances of aerotowing. But I’m sure there are people who could obtain an aerotow endorsement without this level of experience.

I completed my endorsement at Bathurst Soaring Club (NSW), a vibrant club operating from Piper’s Field, a private airfield north of Bathurst and seven nautical miles due west of Bathurst Airport. The gliding community is a fraternity that generally consists of individuals very keen to pass on their knowledge and experience. Ray Humphrey and Brian Bailey of BSC were my instructors, and both were generous with their assistance and advice. Both men are experienced glider and power pilots, a combination familiar to most tow pilots. Their collective experience meant that both were able to pass on tips about operating the aircraft, but more importantly, how to position the towplane and glider on tow (referred to as ‘the combination’) so the glider is delivered close to a thermal.

The formalities involved in obtaining an aerotow endorsement consist of satisfying a CASA delegate that you are competent in glider towing operations. The Gliding Federation of Australia’s (GFA) Aerotowing Manual sets out what is required, and provides detail on the theory of practical operations and emergency procedures. Candidates for the endorsement must have a minimum 100 hours of total aeronautical experience, with at least 40 hours on fixed wing aircraft. The level of gliding experience required may vary from club to club, but currency as a glider pilot on aerotow is necessary as a minimum. I have gone solo in a glider, but wasn’t current on aerotow so was required to satisfy Ray that I was familiar with the aerotow emergency signals by having two glider flights.

The GFA’s Manual also spends time going through the required temperament of a towpilot. Although aerotowing can be seen as a good way to build hours, towpilots must always remember they are flying for the benefit of the glider pilot, not themselves – the glider pilot is paying for the aerotow, not the towpilot. Aerotowing also takes place in the context of a club, of which the towpilot is generally a member, so the towpilot needs to have a cooperative attitude. The gliding community is close knit and a poor reputation will likely follow a poorly-performing towpilot.

Also, simply obtaining an aerotow endorsement does not necessarily guarantee you will tow gliders as you have to establish sufficient contact with a club to be selected for their roster. Given the many benefits to the powered pilot in aerotowing, these are much sought-after positions, and some clubs may not have room on their roster for a new towpilot. It’s best to be patient.

Instruction on the aerotow endorsement at BSC was carried out in VH-PPC, a two-seat, dual-controlled, 235HP, fixed-pitch propeller, Piper Pawnee. The Pawnee was originally designed as an agricultural aircraft in the 1950s but today, generally serves as a towplane. With a fabric-covered steel tube frame, it is of very rugged and simple construction. Its operating characteristics are also simple, both in the air and on the ground. Vision from the cockpit is very good with the seating creating the impression you’re sitting ‘on’ the aircraft. The wide bungee-sprung undercarriage, together with the long tail moment arm, makes it very docile on the ground compared to other tailwheel aircraft. It’s also easy to land – as long as you achieve the correct speed, height and attitude, the undercarriage generally takes care of the rest. Even if you don’t cover yourself with glory and the aircraft bounces on landing, as long as the bounce is not severe, simply maintaining the correct attitude will generally see the aircraft settle.

Significant intervention by the pilot is not required to achieve a straight rollout. The approach to land is made with full flap at 70 knots. As the Pawnee tends to adopt the flying characteristics of a brick once power is reduced, attitude control to maintain flying speed is critical otherwise excessive descent rates will result.

Launching is the greatest challenge. Despite the relatively high power-to-weight ratio of the Pawnee on its own, attach a glider weighing anywhere up to 750kg and watch the overall performance decline significantly. Add other factors such as crosswinds or gusts, high temperatures and density altitudes, challenging airstrip conditions, and the towpilot really has their work cut out for them. Remember, for the glider pilot, unstable air and high temperatures are what they want – exactly the conditions the towpilot must operate in. With all of these factors in mind, the main point that was drummed home to me during my endorsement training was that the towpilot is the pilot in command of the combination. Therefore, he or she has the last say in deciding whether or not to launch. Glider pilots may be very keen to launch, so the towpilot must have the confidence to make the correct decision.

Once the glider is attached, the towline is taut and the ‘all out’ signal is given. Full power is applied smoothly but rapidly. Fast acceleration and propwash from the towplane is critical for larger gliders whose ailerons do not achieve authority until significant airspeed is attained. The glider generally achieves separation before the towplane – in doing so the tail of the towplane will generally be lifted by the glider, requiring no great forward stick pressure by the towpilot. In this state the combination will generally accelerate reasonably well, but care must be taken to ensure correct inputs for any crosswind are used. Some pilots deliberately use asymmetric aileron and rudder to place the tug on the upwind wheel; this allows the tug to accelerate faster due to the lower friction, as well as counteracting any crosswind. Having achieved climbing speed – generally anywhere between 65 to 75 knots depending on the glider type – the climbing attitude is adopted. However, sometimes flying in ground effect immediately after liftoff is necessary to accelerate to climbing speed.

This describes the ideal takeoff. But add some crosswind, gusty conditions and an inexperienced glider pilot (or towpilot), and things can start to get exciting very quickly. If there is a strong crosswind, once the glider has separated it can potentially pull the towplane’s tail downwind, with the towpilot suddenly finding themselves involuntarily pointing towards the airstrip’s side markers rather than along the strip. Skipping and jumping sideways across the ground can be quite disconcerting. Also, unstable conditions can cause the glider to move out of station while on tow – too much slack in the towline can pull and jerk the towplane around quite significantly when it suddenly becomes taut.

The prospect of either an engine failure on takeoff or an unexpected downdraft causing excessive sink also needs some forethought. The high level of responsibility that rests with the towpilot must be understood. Until a safe altitude has been reached the only option for the glider - where it is released from the towplane in an emergency - may be to fly straight ahead. This could mean the glider will either hit the boundary fence at the end of the airstrip or plough into a line of trees, with neither prospect likely to have a good outcome for the glider pilot or their position on the roster!

Experienced towpilots have told me that a towpilot must never release a glider unless there is sufficient height or airstrip length for it to recover. Therefore, unless the towpilot strongly believes there is sufficient length remaining on the airstrip for the glider to stop if the towpilot releases the glider during takeoff because of an emergency, the towpilot is committed to continue to tow the glider up to a safe height that provides options for the glider.

Once a safe takeoff has been achieved, the main goal is to position the glider where the glider pilot is most likely to find a thermal immediately after release. This is where knowledge of meteorology, cloud formation and local conditions all come in very handy. It is critical during this time to be on the lookout for other aircraft in the air, especially as you are most likely to be delivering the glider to an area where other gliders are already thermalling.

Although there are target climbing speeds for all gliders, the focus in the climb to altitude should be on holding a stable attitude rather than chasing airspeeds. Direction changes should be made positively, with the heading not being allowed to wander while traveling in a straight line. This makes it easier for the glider pilot to remain in station.

Most aerotows are up to 2,000-3,000 feet AGL, but experienced glider pilots may release as early as 1,000 (feet AGL). Once the glider is released, power is reduced, cowl flaps are closed (if fitted), a left descending turn is made, and the towplane positioned to most efficiently and safely enter the circuit to land. A thorough lookout during this phase is vital to ensure no conflicts arise with gliders returning to land. Landing may present challenges as there may be gliders on the strip that you need to land between or beside. The approach path needs careful consideration to avoid obstacles on the ground as the 55 metre long towrope hanging off the back of the aircraft hangs approximately 40 feet below the aircraft when landing.

Once back on the ground, the towplane is taxied back into position for the next launch. The launch-release-landing cycle may only take a few minutes and may be repeated until all gliders have been launched, so the towpilot may complete around a dozen launches in a row. The dangers of fatigue are real in this environment, so re-hydration, food and rest are very important for safe operations.

The final few hours at BSC were challenging for me – a strong crosswind from the right that couldn’t decide whether it was a tailwind or headwind, changing runway directions and a busy schedule. However, this provided an ideal training environment for earning my endorsement.

This type of flying is all about ‘stick and rudder’, where complete confidence in the operation of the aircraft is an essential prerequisite to command towing operations. It has made me more self-assured as a pilot, and I look forward to many hot, unstable days when I’m asked to take a glider pilot and his glider in search of the perfect thermal.