Originally Posted by
NeoFit
studi
And what about ORY 1994 Tarom serious incident ?
(so sorry, but it's my own hamster wheel ;-))
As studi says, completely different type, completely different systems design. Notably the old A300/310 system had a very loud warning bell when the trim went too far out of position. Of course, those types were not FBW and as such were not designed to have a constantly-correcting automatic trim - a loud bell signifying trim movement would quickly become a nuisance with the FBW design.
Originally Posted by
Lyman
That too, is interesting. The Stabiliser, in Full NU adds 13 degrees to the elevators deflection relative to the airstream. I submit that had a great deal to do with the extreme high AoA into and through the STALL. At deflection of 30 degrees, plus 40-60 AoA, the elevators are acting more like spoilers than elevators. At the highest, they are lift fences at ninety degrees to airflow. All drag, no lift.
With a traditional empennage design, and with all control systems functioning, it is never completely impossible to un-stall the aircraft due to aerodynamics. The limiting factor is purely time (i.e. how long you have before running out of altitude to recover), and if the PF had pushed the stick forward and held it there, the THS would have come forward and recovery would have been straightforward in a matter of a few seconds (presuming that the recovery was effected with enough altitude to spare).
By looking at the DFDR traces, it's evident that the aircraft did not stay nose-high all the way down. What happened was that the nose came down, the speed built up, but the elevator and THS position caused it to pitch back up again - just like a paper dart running out of speed.
The THS went to full-NU as quickly as it did because the PF was still pulling up as the aircraft ran out of the speed at apogee and continued pulling well into the stall. The aircraft only ever did what was demanded of it.
Remember that spoilers work as they do because of their relative closeness to the aircraft's centre of gravity. Spoilers wouldn't work on the tail because they'd cause the extreme pitch-up moment that was seen when the nose dropped in the AF447 sequence - due to being placed well aft of the aircraft's CoG.
@Organfreak - I don't know if you can see this, but I don't think I've ever even hinted that the Airbus systems design is perfect (hell, I'm a software guy and know full well there's no such thing!). All I've ever objected to is kneejerk assertions that such-and-such a change would make things better, when the people suggesting it don't fully understand the decisions behind that design - some of whom have never even tried to understand it and work from the basis that it's fundamentally wrong based on their own prejudice.