The launch equipment operator manages ground launch towline speed. Because the launch equipment operator is remote from the glider, it is not uncommon for initial tow to be too fast or too slow. If the towline speed is too great, the glider is not able to climb very high because of excessive airspeed. If the towline speed is too low, the glider may be incapable of lift-off or could stall after becoming airborne. Once airborne, the glider could be incapable of further climb. The pilot should use appropriate signals to direct the launch operator to increase or decrease speed. The pilot must anticipate and be prepared to deal with these situations. In the event these abnormal situations develop, the pilot’s only alternative may be to release the towline and land ahead.
Wind gradient (a sudden increase in windspeed with height) can have a noticeable effect on ground launches. If the wind gradient is significant or sudden, or both, and the pilot maintains the same pitch attitude, indicated airspeed increases that could exceed the maximum ground launch tow speed could occur. The pilot must adjust the airspeed to deal with the effect of the gradient. When encountering a wind gradient, the pilot should push forward on the stick to reduce the indicated airspeed. [Figure 8-15] The only way for the glider to resume climb without exceeding the maximum ground launch airspeed is for the pilot to signal the launch operator to reduce tow speed. After the reduction of the towing speed, the pilot can resume normal climb. If the tow speed is not reduced, the glider may be incapable of climbing to safe altitude.
Ground launch may be interrupted by a ground launch mechanism malfunction. A gradual deceleration in rate of climb and/or airspeed may be an indication of such a malfunction. If a launch mechanism malfunction is suspected, release and land ahead.
A broken towline is the most common type of problem when doing a ground launch. [Figure 8-16] When there is a towline failure, the glider pilot must pull the release handle and immediately lower the nose of the glider to achieve and maintain a safe airspeed. The distinguishing features of the ground launch are nose-high pitch attitude and a relatively low altitude for a significant portion of the launch and climb. If a towline break occurs and the glider pilot fails to respond promptly, the nosehigh attitude of the glider may result in a stall. Altitude may be insufficient for recovery unless the pilot recognizes and responds to the towline break by lowering the nose.
If the glider tow release mechanism fails, the pilot should fly at airspeeds no lower than best lift over drag (L/D) airspeed. He or she should fly over and then past the ground launch equipment. This method allows the glider towhook back release to activate or the towline weak link to fail. The ground launch equipment is also equipped with an emergency release mechanism in the event the glider tow release fails. If a winch is used, it is equipped with a guillotine to cut the towline. If a motor vehicle is used as a ground launch, it should be equipped with some form of backup release mechanism.
Self-Launch Takeoff Emergency Procedures
The pilot of a self-launching glider should formulate emergency plans for any type of failure that might occur. Thorough knowledge of aircraft performance data, normal takeoff/landing procedures, and emergency procedures as outlined in the GFM/POH are essential to the successful management of any emergency situation.
Mismanagement of the aircraft systems through lack of knowledge may cause serious difficulty. For instance, if the spoilers/dive brakes are allowed to open during takeoff and climb, the self-launching glider may be incapable of generating sufficient power to continue climbing. Other emergency situations may include inflight fire, structural failure, encounters with severe turbulence/wind shear, canopy failure, and inadvertent encounter with instrument meteorological conditions (IMC).
Possible options for handling emergencies are influenced by the altitude above the terrain, wind, and weather conditions. As a part of preflight planning, pilots should review the effects of density altitude on glider performance. The takeoff runway length and landing areas near the gliderport and existing air traffic affect the pilot’s approach and landing decision. Emergency options may include landing ahead on the remaining runway, landing off field, or returning to the gliderport to land on an available runway. The appropriate emergency procedures may be found in the GFM/POH for the specific self-launching glider.