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Old 1st Sep 2008, 22:52
  #12 (permalink)  
BelArgUSA
 
Join Date: Jun 2005
Location: AEP
Age: 80
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Takeoff weight limits

I rather deal (and operate) with an "Accelerate-GO" limitation, than an "Accelerate-STOP" limitation...
xxx
To me, accelerate-stop is a very "hard-defined" distance, where the "far edge" of your usable T/O distance consists of mud and metal or trees, which will have detrimental effect on your jet-powered flying machine. The steel of the light posts at the other end of your runway is much "harder" than the aluminum of the nose of your airplane.
xxx
Should you venture to "abort your takeoff" and end-up in the mud by 20 meters beyond the end of the runway, you will become the subject of a thread and 719 postings by the Pprune accident investigators. In a "accelerate-go" non-incident you survived, passing the "screen" with only 10 (or less) feet above your obstacles, will not be known to that SLF, a reporter for the Daily Mirror, who happens to have enjoyed two "before takeoff whiskies" in his seat nº 3C of your cabin...
xxx
As per flight safety, I always "knocked" a few "knots" from V-1 speed on wet runways. And yes, when I started airline flying in 1969, I eventually read "Fly the wing" by Jim Webb. And "Handling the big jets" by D.P. Davies became (and still is to this day) my bedside favorite book, next to my bible.
xxx
My decision to continue takeoff (not to abort) is briefed and indicated to the other pilot and flight engineer by my hands going OFF the thrust levers. I do not waste time in 1 hour-long briefings during taxi, about what V1 is or will be, and what we will be doing, should an engine fail. We all know what V1 means anyway, since the first time we sat in a cockpit.
xxx
No incidents or accidents in my long career, ending for retirement 2 months from now.
Except (maybe) almost one time...
xxx
Dubai - early/mid 1980s - I am captain on a DC8-63F cargo - US air carrier, operating ACMI for Air India. We came from Madras (Chennai) and destination was Milano Malpensa. The experienced F/O was dealing with weight and balance, and I took care of performance and speeds. Next sector was my flight..
xxx
The Dubai agent asked if we could carry "extra payload" to MXP. He asked "how much" - The F/O said "twelve thousand". The agent acknowledged. The F/O had meant POUNDS as a good American boy he was, and the nice Air India agent understood KILOS... In that part of the world, 12,000 certainly becomes 13 or 14,000 in practice... Airplane got loaded, we taxied for takeoff, at a computed maximum weight of about 355,000 lbs, we were performance limited despite the long runway. The flaps were to be set at 18 for takeoff.
xxx
Close to reach published V1, it became evident to me that we were not going to "make it". Maybe the only day in my life that I exercised superior airmanship, I moved the thrust levers forward to the stops (F/E hand came to reduce some of it) and I called (actually yelled) for "flaps 23" which the F/O immediately selected without asking a question.
xxx
Should we have "aborted" the T/O, we would have been a statistic of the NTSB. Sure, more flaps reduced the "2nd segment" gradient but it also avoided the airplane stall. As I could not pull more "nose-up" (stretched DC8s are limited to 8º rotation), the extra lift got us to fly above the obstacles by the end of the runway, not by the "35 feet" of FAR 25... Who knows, we cleared them by only 10 or 15 feet...
xxx
By chance I had an excellent crew with experience, and we all learned of our mistakes. How heavy were we, I would estimate we were at 370,000 lbs.
I believe, having a crew (in the name of modern concepts of SOPs) reducing the power to maximum EPR, N1 or EGT limits, and ignoring the "flaps 23 call" because it is "not in the procedures" would have made the three of us become some name statistics of aviation accidents. And the reason would have been "pilot error - crew failed to compute proper weight, and failed to observe standard procedures".
xxx

Happy contrails
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