Originally Posted by
AirRabbit
I’ll just leave that manual paragraph alone for anyone’s contemplation.
The manual paragraph you have quoted is referring to
inflight icing. What it has to do with attempted takeoff with ice contamination of the upper wing surface, accrued during ground operations, which happens to be the subject of the thread?
Originally Posted by
AirRabbit
My original comment was to correct what I saw as an incorrect impression that it was a the low engine takeoff power that caused the accident. The NTSB officially, and at least one NTSB participant (quoted by one of the posters here) collectively agreed that the engine power setting did not cause that accident.
There is no dissenting opinion included in the NTSB report. NTSB is pretty clear that too low power did not cause the accident on its own but that without it, the catastrophe would not have happened:
Originally Posted by NTSB AAR82-08
The aircraft could not sustain flight because of the combined effects of
airframe snow or ice contamination which degraded lift and increased
drag and the lower than normal thrust set by reference to the erroneous
EPR indications. Either condition alone should not have prevented
continued flight.
The story about NTSB member disagreeing with it comes from the anonymous poster on the anonymous forum where every post comes with caveat:
Originally Posted by PPRuNe staff
As these are anonymous forums the origins of the contributions may be opposite to what may be apparent. In fact the press may use it, or the unscrupulous, or sciolists*, to elicit certain reactions.
Originally Posted by
AirRabbit
The NTSB reached the conclusions they reached.
As presented, it is a perfect tautology. However, NTSB has quite comprehensively documented the method of getting to conclusions, while on the other side...
Originally Posted by
AirRabbit
Some of us in the aviation world disagree with those conclusions … welcome to the world of individuality.
...most of those disagreeing with NTSB conclusions just say it-was-not-so, without further reference or with unverifiable reference at the best. Every individual is entitled to his own opinion but in my humble opinion that no one is entitled to his own set of facts should not be debatable.
Originally Posted by GSLOC
We all know that stall warning won't occur (in ice-contamination case) when actual stall happen because system does not measure disturbed air flow and contamination on wings.
Actually, we shouldn't be knowing that. The effect of ice contamination is dependent on so many variables that it is impossible to quantify it except in the postmortems. In Air Florida 90 case, Cd was affected far worse than AoAcrit, so the crew got the stickshaker before stalling - which combined with misplaced belief that stall always comes before stickshaker when wing is contaminated resulted in some wrong theories. What you referred to is worst case scenario while the best case contamination scenario happens any given snowy day; certification margins are not entirely eaten up at half-the-wingspan height and aeroplane happily flies away.
Originally Posted by GSLOC
Can they for instance command pitch that is in excess of reduced critical AOA?
They can command the pitch that would lead to flight path that would lead to AoA exceeding AoAcrit of contaminated wing, however, chances for such adverse contamination combined with low V2 are very slim. "Pilots" have to determine how lucky they feel. Pilots de-ice and anti-ice if needed but do their best to ensure nothing except de-cing fluid is on their wings as they push the thrust levers far forward. Wordgames such as the exact meaning of "adherence" and "takeoff" don't come into play.