Downwind landings are always a balance between going too slow or too fast. With a tailwind there is an illusion of increased speed. This could allow the aircraft to be flown too slowly, increasing the chance of a stall. However if the aircraft is flown too fast to compensate for this, there is more likelihood of running out of runway. The key is to trim the aircraft to the minimum approach speed plus a margin for any gusts. One-third the wind speed should be sufficient. Students having the fundamental habit of letting the aircraft fly on its own after it’s trimmed shouldn’t have any problems with speed control.
The next factor is the amount of runway that will be used. The best plan is to pick a round out point as close to the threshold as obstructions will allow. Once the glider is on the glidepath for this, use full spoilers, sideslip, and flap (allowing for obstruction clearance), and don’t be too concerned if the glider now flies below the original glidepath. Once the aircraft is below 200 feet, any radical sideslip will be reduced to a sideslip for drift control, and closer to the ground, full spoiler will be reduced to prevent a hard landing. A fully held off landing will allow for the shortest ground roll. If the field is long enough this is always the best choice, as the aircraft will touchdown with the lowest possible energy. On touchdown, the wheel brake should be applied promptly as required. Students must be proficient at normal landings before attempting this exercise. The outline for this exercise is:
- Student and ground personnel briefed that a downwind landing will be attempted.
- Student checked on knowledge of current conditions and how this will relate to drift correction with the downwind circuit and landing.
- Student flies as normal until circuit for downwind landing approaching.
- Circuit is best entered mid-downwind, with downwind checks already done. This allows time to change the circuit if conditions and traffic have changed.
- Student coached into proper circuit and glidepath for the downwind conditions. Instructor is prompt with all corrections to ensure safety.
- Student coached in use of spoiler and sideslip and proper height to flare under these conditions.
- Student coached on drift control, round out, use of brakes on rollout.
- Instructor ensures aircraft is promptly moved after full stop.
If at all possible, a downwind landing should be done separate from the rope break training. Try this exercise when there is light traffic and fly a circuit joined from the mid-upwind position keeping a good eye out for other traffic flying the regular circuit. You should approach the mid-upwind circuit from an angle and determine if the traffic will allow you to practise this exercise or if it will be necessary to abort and fly a normal circuit. The key points of the exercise itself are speed control, aiming point, and descent rate. It is important to establish a normal approach speed perhaps 5 knots above the minimum no wind approach speed and trim for this well in advance. Landing downwind will produce the illusion that the airspeed is higher and over compensation on this point can lead to using excessive amounts of runway. For the same reason it is important to pick aiming points close to the threshold of the runway and use both spoiler and sideslip as necessary to use as little runway as is possible. However if full spoilers have been used, these should be moved to the 2/3 open before touchdown as hard landings may result. Give students the objective to stop before an imaginary object (brick wall) that is located only half the distance down the runway.