4.LESSON 34 - FIELD LANDING
- Start choosing a suitable field well in advance
- You cannot rely on the altimeter to estimate your height above the ground
- Run through the pre-circuit checklist before starting the circuit
An important part of gliding is finding enough rising air to fly successfully from A to B. However, you must be prepared for the soaring conditions to change, making getting to ‘B’ impossible and forcing you to land off- airfield. We call these landings ‘out landings’ or ‘field landings’. Fortunately, there are usually plenty of options to choose from for a safe landing.
In this lesson, you and your instructor will explore various field landing options. Well before you arrive at circuit height you must have chosen at least two or three landing options. If you have the opportunity to do this exercise in a touring motor glider, you may want to combine it with Lesson 4.31 (Navigation).
An off-airfield landing can be stressful, especially the first time. Try to stay calm; first and foremost, concentrate on flying the glider. You will see that a field landing is absolutely doable if you take the time to prepare properly.
You should always know whether you will be able to land in an area or not. Especially if you’re flying below 2000ft above ground level, you should start considering which places would be suitable for a field landing. Above an agricultural area, this is more straightforward than, for example, in mountainous terrain or wooded areas. When flying over unsuitable terrain you always need extra height so you can find a way out.
Start choosing suitable fields when passing below 1500ft and plan your circuit options. You will need to make the final decision to land if you do not find a new thermal and descend to below 900ft.
The field landing decision-making funnel
Just as there are useful mnemonics for checklists, there is also one to help you choose a suitable field: W SS SOS. This corresponds to the field landing checklist:
Pay close attention to the wind direction. Landing with a tailwind is strongly discouraged, because it leads to a greater landing distance.
Your field must be big enough for at least the last part of the descent, a normal landing and a ground run without braking. It is best to choose a field that is as long as possible. In a compact field you have very little room for mistakes. If necessary, consider a landing from corner to corner.
Potentially good landing surfaces are: mown grain fields, stubble fields, grass fields and fields with short crop. Try to avoid long crops, such as rapeseed fields; these make keeping the wings level very difficult during the landing and ground run and they might damage your glider. Good advice is: if you can see earth through the crop it is generally okay for landing.
Slope is best seen from the side, rather than from above. Even steep slopes are hard to see from above. Any visible downslope is unacceptable. A slight upslope is acceptable, but keep in mind you need a different landing technique for upsloping terrain. See the next page for landing uphill.
There are many sorts of obstacles to take into account: trees, power cables, buildings and hills that might create turbulence. If you have the choice, then it is wise not to approach over busy roads or crowds as this may cause problems and unwanted attention.
- Obstacles reduce the usable field length by at least 10 times the height you clear them.
- Power cables are almost invisible from the air. Pay close attention to the towers and poles to which they are attached.
Just as you never want to land near people, you also want to land as far away from animals as possible. Horses can be startled, sheep tend to spread in a field, cows are curious and can damage your glider; and a single cow is a bull!
It is best to fly over the chosen field at least once to see if there are any obstacles. Focus your attention on flying a good circuit and ignore possible thermals in the circuit.
Do not lose sight of your chosen field; make sure you can identify it by looking at the surroundings before you start the circuit. Maintain a safe airspeed and monitor your airspeed frequently. It is extra important to perform the pre-circuit checklist when making a field landing. Try to do this before entering the circuit to land, so you don’t forget important parts of the checklist like extending the landing gear.
Position the glider well upwind and fly a normal circuit. Keep in mind the three key factors of the circuit: height, distance and angle. An additional difficulty is that you cannot use your altimeter during a field landing because it is impossible to know exactly what the elevation of your chosen field is. Instead, you will need to estimate the height. If you have a flight computer that displays a reliable height above the ground, you could use that as an aid. Remain at the same distance and angle from your field as you would do during a normal circuit at your own airfield. Unfortunately, this will always be a bit more difficult because the familiar landscape elements are missing. Make active corrections to fly a good circuit and remember you can use the airbrakes at any time if needed. It is best to fly a final approach with half to two-thirds airbrakes extended.
Once you have passed all obstacles on your final approach leg, try to land as soon as possible. Carry out a normal landing and make the ground run as short as possible. Avoid unnecessary rolling out: this reduces the chance that you will hit an unexpected obstacle or drive into a hole. Keep the wings level until you’ve come to a complete stop.
If your wing does get stuck somewhere (for example in a crop), immediately push the stick fully forward to relieve the tail of the aircraft in a ‘ground loop’. This prevents large lateral forces on the tail construction.
While landing uphill is undesirable, it is better than downhill. Sometimes circumstances can force you to land uphill.
Upsloping terrain can appear closer than it really is, leading to an approach angle that is too flat.
The upslope creates the optical illusion that the glider is higher than it really is (see diagrams). If the ground slopes away from you as you approach, the optical illusion makes the glider seem lower than it actually is, leading to a steeper approach than usual.
During round-out (2) you will need to raise the nose more than normal (3 - 4) so you will also need to start the round-out earlier. Be aware that you can rapidly lose speed (5). For this reason, a slightly higher approach speed can help. You should use normal airbrake and normal speed control (1).
RETRIEVING THE GLIDER
You and the glider will probably need to be picked up by road. Before your retrieval crew arrives, it is important that you try and visit the farmer or the landowner.
A glider usually does not cause any damage during a field landing and most farmers won’t mind if you explain why you had to make a field landing.
Remember that if you land anywhere with a glider, you are an ambassador for the sport. Try to make the most of the situation, show them the glider and advertise!