Launching a nonpowered glider requires the use of visual signals for communication and coordination between the glider, towing aircraft, and the ground crew. Ground launching signals consist of prelaunch signals and in-flight signals.
Aerotow prelaunch signals facilitate communication between pilots and launch crewmembers/wing runners preparing for the launch. These signals are shown in Figure 7-1.
Visual signals allow the tow pilot and the glider pilot to communicate with each other. The signals are divided into two types: those from the tow pilot to the glider pilot and signals from the glider pilot to the tow pilot. These signals are shown in Figure 7-2.
Takeoff Procedures and Techniques
Takeoff procedures for gliders require close coordination between launch crewmembers, wing runners, and pilots. Both the glider pilot and tow pilot must be familiar with the appropriate tow procedures. The assisted takeoff includes a wing runner that holds the wing in a level position. An unassisted takeoff does not include a wing runner or other ground crew. The unassisted launch requires good procedures and should only be attempted by highly experienced glider and tow pilots. It is recommended that all takeoffs include a ground crewmember for traffic scanning and general assistance during the takeoff.
It is very important to never connect a glider to a towplane or towline unless the pilot is aboard and ready for flight. If the pilot exits the glider for any reason, the towline should be released and disconnected because some hitches like a Tost hitch require slight pressure for the tow ring to actually move from the jaws. If no tension is applied, the ring stays in place and connected when the jaws close.
Normal takeoffs are made into the wind. Prior to takeoff, the tow pilot and glider pilot must reach an agreement on the plan for the aerotow. The glider pilot should ensure that the launch crewmember is aware of safety procedures concerning the tow. Some of these items would be proper runway and pattern clearing procedures and glider configuration checks (spoilers closed, tailwheel dolly removed, canopy secured).
When the required checklists have been completed and both the glider and towplane are ready for takeoff, the glider pilot signals the launch crewmember/wing runner to hook the towline to the glider.
Normal Assisted Takeoff
The towrope hookup should be done deliberately and correctly, and the release mechanism should be checked for proper operation. The launch crewmember/wing runner applies tension to the towline and signals the glider pilot to activate the release. The launch crewmember should verify that the release works properly and signal the glider pilot. When the towline is hooked up to the glider again, the launch crewmember repositions to the wing that is down. When the glider pilot signals “ready for takeoff,” the launch crewmember/wing runner clears both the takeoff and landing area, and then signals the tow pilot to “take up slack” in the towline. Once the slack is out of the towline, the launch crewmember verifies that the glider pilot is ready for takeoff; this may include a “thumbs up” by the glider pilot. The crewmember/wing runner does a final traffic pattern check, and then raises the wings to a level position. With the wings raised, the crewmember/wing runner then signals the tow pilot for takeoff. At the same time, the glider pilot signals the tow pilot by wagging the rudder back and forth, concurring with the launch crewmember’s/wing runner’s takeoff signal. If a radio is used, the glider pilot advises the tow pilot that he or she is ready for takeoff, stating “Canopy and dive/air brakes closed and locked.”
As the launch begins and the glider accelerates, the launch crewmember/wing runner runs alongside the glider, holding the wing level. When the glider achieves lift-off speed, the glider pilot should allow the glider to become just barely airborne and level behind the towplane’s tail, as it accelerates to climb speed. The glider pilot must be precise in controlling the glider at this very low altitude of 2 to 4 feet, more or less depending on the aircraft involved. Any large excursions from the position of level directly behind the towplane’s tail can lead to disaster for the tow pilot and the glider pilot(s). The glider pilot must not climb above the towplane’s tail, as this can force the towplane’s propeller into the runway surface. Lateral glider deviations side to side can drive the towplane off the runway. The glider pilot should maintain this altitude by applying forward stick pressure, as necessary, while the glider is accelerating. Once the towplane lifts off, it accelerates in ground effect to the desired climb airspeed, and then the climb begins for both the glider and towplane.
During takeoff while at very low altitudes, it may be necessary to steer the glider solely with the rudder due to the very long wings of most gliders. The long wings, combined with very short landing gear stances, make gliders prone to hitting runway lights and signage. Keeping the glider’s wings level helps prevent collisions with obstructions but restricts aileron usage close to the surface. Control the bank angle of the wings with the ailerons. Full deflection of the flight controls may be necessary at low airspeeds, but the flight controls become more effective as airspeed increases. [Figure 7-3]
In most takeoffs, the glider achieves flying airspeed before the towplane. However, if the glider is a heavily ballasted glider, the towplane may be able to achieve liftoff airspeed before the glider. In such a situation, the towplane should remain in ground effect until the glider is off the ground. Climb-out must not begin until the previously determined climb airspeed has been achieved.
One of the most dangerous occurrences during aerotow is allowing the glider to fly high above and losing sight of the towplane. The tension on the towline caused by the glider pulls the towplane tail up, lowering its nose. If the glider continues to rise, pulling the towplane tail higher, the tow pilot may not be able to raise the nose. Ultimately, the tow pilot may run out of up elevator authority.
In some towhook systems, the high pressure loading on the towhook causes towhook seizure, and the tow pilot may not be able to release the towline from the towplane. This situation can be critical if it occurs at altitudes below 500 feet above ground level (AGL). Upon losing sight of the towplane, the glider pilot must release immediately.