Emergency Glide Ratio

[misd-agin]

Your link didn't work.

The decision to retract flaps depends upon how much altitude you have below you. If you are at 10,000 AGL then retracting the flaps would make sense.

[Pugachev Cobra]

Here's a working link for the same filename from the FAA website:

http://www.faa.gov/library/manuals/a...83-3a-4of7.pdf

[Love_joy]

The decision to retract flaps depends upon how much altitude you have below you. If you are at 10,000 AGL then retracting the flaps would make sense.

I have to agree with FI no.1 - but there is a caveat here.

During my flight training I was also drilled into not retracting flap on approach, the pitfall being that you retract flap at a speed which requires it to maintain a buffer against Vs. On approach, you may not have sufficient height to recover.

That said, if you have drag flap out and need to 'stretch' the glide - get rid! But be aware you need the speed first.

[Pugachev Cobra]

Relevant to this thread, the BA038 777 Captain was interviewed and mentioned his decision to retract the flaps, so that he could extend his gliding range.

BBC News - Hero BA pilot speaks of Heathrow Boeing 777 crash

Is it wise to apply this experience into lighter aircraft as well, as was the original post's topic?

[FullWings]

Is it wise to apply this experience into lighter aircraft as well, as was the original post's topic?

If you're in a similar situation (developing undershoot) then it's worth a try, especially if you're not going to make it if you don't do something. As has been pointed out, most people fly light aircraft around the circuit (and on approach!) considerably faster than the clean stalling speed, so "falling out of the sky" is unlikely.

There are so many variables involved that there's no real hard and fast answer to this particular scenario. There are three basic outcomes: a) flap or no flap, you'll make it b) the right flap setting/speed/trajectory will get you in, the wrong ones won't and c) you're not going to make the airfield, whatever you do. The "approach cone" containing b) is likely to be fairly narrow. It's energy management: you start off with a certain amount of mgh+0.5mv^2 and wish to make the most of it on the way down.

There's speed<->altitude trading, ground effect, wind gradient, airmass motion and a load of other factors. Unsurprisingly, there's no one answer that fits all. If you can see where your trajectory will end and it's not good, then change the configuration; if it's still looking bad then...

What happens when the engine quits is down to workload, experience and currency. There are also external influences such as wind, whether the prop is stopped or not, aircraft weight, etc. What is important (and stated in the BA38 report) is that if you're going to crash, do it wings level and keep flying the aircraft until the end. As they say, a good approach into a poor area is better than vice-versa. Recognise that you're about to have an accident and make it a controlled one.