Ladies and gentlemen, dear PPRuNers, honourable participants in our discussion, I would like to take an opportunity to kindly ask you to get acquainted with The Book:
It will do you a lot of good and also might help reduce the PPRuNe bandwidth wastage.
If you have third edition on your bookshelf, you might find the following chapters useful:
Pg 109, Stalling, which shows that pilots' wildly divergent views on the subject of stalling have preceded PPRuNe by decades. Also displays DP Davies fantastic ability of insight, in matters not just technical but also in human nature.
Pg 128, Stick shakers.
Pg 130, Stick pushers.
Stickshakers are not supposed to be universal stall warning devices! They are fitted to aeroplanes that have no pronounced natural pre-stall buffet or margin between buffet and stall is to thin for buffet to be used as effective deterrent. Why A330 doesn't have it installed? Two possible clues in the final report.
Originally Posted by BEA Final report on AF447, English version, page 93
Airbus subsequently flew special flights to collect more accurate data at high angles
of attack and with an aircraft configuration close to that of the accident (mass, flight
level, Mach, etc.). These tests made it possible to refine the preliminary correlations
and to establish that the level of buffet was considered to be a deterrent by the test
pilots when the angle of attack was about 10°, corresponding to normal acceleration
amplitude of 1 g at the pilot’s seat.
Originally Posted by BEA Final report on AF447, English version, page 187
When there are no protections left, the aeroplane no longer possesses positive
longitudinal static stability even on approach to stall. This absence specifically results
in the fact that it is not necessary to make or increase a nose-up input to compensate
for a loss of speed while maintaining aeroplane altitude. This behaviour, even if it
may appear contrary to some provisions in the basic regulations, was judged to be
acceptable by the certification authorities by taking into account special conditions
and interpretation material. Indeed, the presence of flight envelope protections
makes neutral longitudinal static stability acceptable.
So 330 both shakes out of her own accord and did receive some special dispensation in certification process by virtue of her envelope protection.
Now about stick pusher: it is not stall recovery device, it is stall prevention device! It has to be fitted to aeroplanes with unacceptable stall characteristics. e.g. pitch-up at stall or prone to entering the deep stall. As anything else related to aeroplanes, while solving some problems, they bring in some problems of their own (HTBJ, pg 131) so claiming they are stall recovery devices and suggesting they should be installed on any aeroplane to deal with the problem of distracted crew would be sparkling display of aeronautical ignorance.
Since for nine years I have been earning my daily bread flying the aeroplanes equipped with both stick shakers and stick pushers, implying if I ignored the stall warnings and somehow pulled them into stall they would bite without warning and once stalled would stand good chance to be unrecoverable, one might perchance find understandable that I view the propositions to indiscriminately train each & every airline pilot in full stall recovery procedure with considerable amusement.
Originally Posted by Lyman
Your "15" degrees PITCH UP I believe came from the DFDR, via ins and archive. You know the Pitch attained was not nearly that high, in the initial command post a/p loss.
Yea... it was measly 13 degrees. Far too high for cruise anyway but compatible with the ardent desire to climb and having no idea aeroplane has insufficient performance to fulfill her masters wish - yet she attempted to obey into her eventual destruction.
Originally Posted by Ok 465
727 2-engine out, manual reversion, NDB approach to NDB minimums was essentially a one maneuver check-ride.
What was most interesting, was not who succeeded or failed at the maneuver, but who would be enthusiastically willing to attempt it.
Emphasis is mine but this is one of the most precise hitting the nail on the head that can be found on the PPRuNe.
Originally Posted by lyman
Look, Sir, it is getting tiresome that you expect to make a glib comment about a failure of some piece of equipment and expect others to accept your pronouncement as 'end of discussion'.
Maybe it's just me, but when someone counters to spectacularly wrong theory with some solid facts disproving it, least I expect it would mean the end of that particular direction of discussion.
Originally Posted by DozyWannabe
he AP will not re-engage itself automatically in any scenario, and because Alt2 was triggered and latched in the case of AF447 even a manual attempt to re-engage AP would have been denied.
Sorry Dozy, I missed the part where this was discussed. Could you provide the reference that states latching of ALT2 permanently disables the autopilot? I need to get my head around this.