HazelNuts39, thank you for correcting me. I was under impression that 1G shake is far too excessive, yet it seems that's just what AF447 went prior to stall. I don't think such a heavy vibration can be ignored, seems that crew either totally freaked out and was unable to understand what was the source of it or somehow believed they have strayed into Cb and it was turbulence.
IMHO, magenta line on real fig 64 (report in French) makes one of the most depressing reads in the report.
Originally Posted by rudderrudderrat
Time 0hr.09min FL. 34.992 Static temperature (°C) -43.5
Time 2hr.10 FL 35.044 SAT -38.8
(...)
The TAT has warmed from -42°C to -38.8°C over a very short time.
That "very short time" was
two hours.
Originally Posted by Lonewolf 50
The PF was task saturated.
Saturation was self inflicted. Had he recognized sudden drop in speed for what it was and called out UAS, we wouldn't be discussing the AF447 case any more than we did all the other loss of airspeed indication on TA Airbi. Damn it, if he only got shocked into paralysis, he would be better of.
Originally Posted by Lonewolf 50
Training issue, and possibly an Airbus and Air France Indoctrination Issue. Education and training go hand in hand with indoctrination.
Possibly. Maybe it goes even deeper, down to flight schools and "Principles of flight" lessons.
Originally Posted by gums
For those that have not flown a FBW system
Thank you for explaining the way FBW works on F-16. FBW is just generic term and different FBWs can be set up in radically different manner. Compared to Viper's, Airbus' is "same, same but different". It has no G-trim, it is flightpath stable. So no need to trim it in climb or pull in turns. Stick free, it follows the flightpath.
Originally Posted by gums
And now, Airbus shows us that the jet DOES HAVE a point on the pitch coefficient curve that is "neutral".
Well... no. Aerodynamically it is stable yet with FBW intervention in ALT2 law, where low and high speed stability are lost (as is expected when there is no reliable speed measurement), it does not become neutral but unstable.
Originally Posted by gums
Personally, a buffet of 0.1 gee Nz seems adequate to provide a warning without any fancy chimes/clangs/etc. And a buffet much higher than that once in the stall should have been a very big indication of what the jet was doing.
Actually, I was mistaken. It was ten times as much.
Originally Posted by gums
The high-speed indications for sub-sonic designs usually involve a high frequency "buzz" or vibration.
Herein lies the problem; wings design advances much faster than textbooks are updated. Boeing 757, entering service in 1983 needs mach trim. Airbus 320, entering service in 1988 needs it not. Airbus 330, entering service in 1994 does not suffer from mach buffet at all and has so steep drag rise past Mmd it is very hard to overspeed her. While AoAcrit is always affected by mach no, the effect is much more pronounced on 330 than on 320. Yet, all the time there are many airmen still learning from the books of yesteryear, unable to tell which chapters still apply and which not so they keep on seriously discussing about pitch-up of swept wings when stalled, aileron reversals, coffin corners... almost as if MiG-17 is the current state of the art.
Originally Posted by rgbrock1
I think this part of BEA's final report could explain why both PNF and PF did not recognize approach to stall nor the stall itself, no?
No. It would have been an issue, if the crew pulled up, let go of the stick(s) and aeroplane pulled and trimmed into stall by itself, FBW fighting to maintain the flightpath as the airflow over the wings got detached. There is no way to check for positive static stability without controls at neutral and right stick was largely nose-up.