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Old 18th May 2007, 09:17
  #10 (permalink)  
old,not bold
 
Join Date: Apr 2006
Location: uk
Posts: 757
It's sackcloth and ashes time.....

I was indeed confusing RESA and Stopway, and I've just finished banging my head against a wall to try and erase the embarrassment, without success. I'm supposed to have airport manager, inter alia, on my CV, for God's sake.

What I was getting at was not the RESA, ie the subject of this thread, and the longer the RESA the better, of course, and of course this has no efffect whatsoever on V1.

I was getting at the stopway, and at the risk of drifting the thread, my point is that the trading of pavement, as "an economical substitute", is only valid if the stopway can indeed "support the aeroplanes it is intended to serve". My personal view is that it should do a lot more than that if the ASDA, balanced field length or whatever, includes it, and I do not believe that many stopways even fulfill the "support the aeroplanes..." need.

A Stopway "need not have the same bearing or wearing qualities as the runway with which it is associated". I have always thought that this is a fudge. Why not? It is there, says the book, to be "a suitable area in which an aeroplane can be stopped in the event of an abandoned take-off".

Strangely the book does not say "safely", but we can assume that it is implied. A very heavy aircraft, at its maximum permitted mass, takes some stopping from V1, especially if the reverse thrust is asymetric, or would be if used at all. (Is another fudge the manufacturer's figures for stopping from V1? I don't know, but I often wonder.)

If the airport owner is minimising TORA while maximising ASDA, ie the "economical substitute", the aircraft will hit the stopway at some speed, while carrying out full braking. Even dry, on many stopways the nose and main gear will sink a little. After heavy rain it could be much worse.

So I stand-by the assertion that at many airports it is only "in your dreams" that a big, heavy aircraft can be brought safely to a halt without a risk of undercarriage collapse at least, within the stopway, after abandoning a take-off at V1, especially if the aircraft is a heavy twin with a failed engine.

But I apologise to all for the drivel that was my previous post on this subject.
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