During glide approach or practice force landing, I can see the aim point moving down. It means the aircraft will overshoot the field. But I am not sure when should flaps be used or which stage of flaps should be used. I concern that deploying flaps too early, the aircraft will not make it to the field.


This is not so much for normal power-on approaches, but the proper way to manage a forced landing approach is to use some way other than flaps to vary your sink rate as required. Gliders do it with spoilers, which allows the glider's descent angle to be varied between maximum glide and nearly straight down at any time, which is why the one-shot landing aspect of gliders is really not such a big deal; it's easy to place it anywhere you want.

With power planes you use a forward slip as your variable drag tool. As you are getting in close, a few hundred feet, you drop just takeoff flap to lower the stall speed and apply some forward slip, ideally roughly half of the maximum you can apply, to be about what seems to give you the correct descent path.

It's as if you had some power. If you are overshooting, increase the slip angle to descend steeper like you were reducing power, if undershooting, decrease the slip to descend less steep like you were increasing power (a little bit).

Don't drop landing flap until you are down to the last hundred feet or so when making the field is assured. Just about all aircraft can be slipped, but some may be restricted from slipping with full flap.

If you use and practice this method you will get good at placing the airplane precisely into a forced landing spot without power, and a forced approach will lose its terror as long as there is an open place to land. I'd be disappointed with an instructor who wasn't teaching slipping to control descent rate in a power off emergency.

  • $\begingroup$ Yes. It's rather like asking "How do you catch a ball?" You can't really explain it - at least I couldn't - but you learn by practicing, $\endgroup$
    – jamesqf
    Mar 23 '19 at 17:49
  • $\begingroup$ I don't advocate it but I actually use a more radical procedure for force landing scenarios. My plane has manual flaps, worked by a center lever, which are quite powerful (won't work so well with electric ones). I start out at half flap and if I need to adjust glide path, I hold the latch button down and work them up and down between 1/4 and 3/4 as if they were spoilers, coordinating pitch inputs to compensate for the changes caused by flap extension and retraction, and carrying a bit of extra speed margin. It works quite well and I can place the airplane very precisely if I have to. $\endgroup$
    – John K
    Mar 23 '19 at 18:02
  • $\begingroup$ They should have a "trim wheel" for flaps instead of only 3 settings. Landing by adding drag means you're high a bit, which means you'll make the field. Safer for single (or no) engine. But that's pretty much what a forward slip is. $\endgroup$ May 26 '20 at 12:18

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