John Farley's thoughts on forced approaches
I was looking through some files yesterday, and happened across a passage written by our respected past member John Farley. John was a highly experienced test pilot, who was a wealth of wisdom, and an asset to our knowledge here during his time. After reading his book "A View from the Hover", I made the trip to spend a day with John, and was rewarded with many gems of wisdom. Among them, were John's thoughts on forced approaches. Though this wisdom is of moderate applicability to most well mannered, low drag GA planes, I can say that I have applied the technique in rather draggy types, and with some moderation, it works, and keeps you safe. During flight testing of a higher gross weight, Cessna 182 amphibian, forced landing precision benefited from this technique. Certainly an attempt to land power off from a "best glide speed" approach would have ended in pain. Hence my fight manual supplement for the modified plane specified a much faster glide speed, with corresponding reduced expectations in gliding distance.
In any case, here is a passage written in John's book (which I highly recommend):“A View from the Hover” page 354:
“…. A few years later, I found myself on Aero Flight at Bedford where we operated several very valuable single engine prototype research aircraft. The boffins were naturally very keen not to lose one of these just because the engine stopped. Without exception, the aircraft were all the aerodynamic opposite of a good glider. In the jargon they were low lift over drag devices (low L/D) which meant that they all had very steep glide angles.
We have now arrived at one of the most enduring myths of aviation. Aircraft that glide down a 30 or 40 [degree] angle must be awful to land. Wrong. Totally wrong. They are the easiest of them all so far as the final approach and landing goes. Only when I started practising glide approach and landings for aircraft of that type did I start to get a 100% success rate with smooth touchdowns, just after the runway numbers, and at the correct speed. Because of the steep glide angles, it is necessary to be pretty close to a suitable runway when the engine stops. The difficulty that had previously dogged me of looking out the window in order to judge the shallow glidepath and so how to fly around the circuit, just vanished. With the nose apparently pointing straight down at the ground you can see exactly where you will impact if you do nothing. Wind is not an issue and there is nothing to judge. All you do is to throw down the gear and flaps, dive at the flap limit speed, and point the thing at the beginning of the lead in lights (or just short of the runway if there are no lead in lights). Then pull out of the dive at the last moment and fly level, as low as you dare, until the speed bleeds to the one you want for touchdown. This way you impress those who do not realize how easy it all is by plopping it on the numbers. If there are any Hunter pilots out there who read this, try gliding it with gear and full flap at 250 kt and you will see how well it handles – except in manual. Handling is excellent during the flare because of all the speed. What you must not do is to try to land a low L/D device from a descent at its best glide speed, as you will be very disappointed when you try to flare from the steep approach. In 1982, doing AV-8B engine work at Edwards over the lake bed, I had over two hours of gliding in 40-odd episodes with never a concern, should a relight fail. I started each sortie with a practice engine chop climbing through 15,000 ft or so, and then, with the wheels and flaps down, did the practice ‘dirty dart and flare’ over the lake bed as a bit of very enjoyable legalized hooliganism. High risk stuff so far as some onlookers were concerned. But you know better. Of course glider pilots know all about the use of drag to make approach and landing easier. That is why they set up the approach with airbrakes out, and pop them in at the first sign that they are going to land a bit short.
If you are a power pilot who has trouble with doing the occasional glide approach you may (secretly) wonder how glider pilots have the skill and judgement necessary to do it every time. May I suggest a reason for their success? Currency.”