Originally Posted by OK465
I'm having a problem with understanding that an A/P pb will physically engage in 'latched' ALT2 when it wouldn't engage during the period of time that the condition precipitating the latching was in effect.
Seems that FCS gives up restoring itself back to normal law after it detects long lasting ADR disagreement, however AFCS keeps checking indefinitely and will restore itself as soon as two ADCs agree, not necessarily at correct value. Page 86 of the report refers.
Originally Posted by OK465
If you were able to get the A/P pb to engage in ALT2, what would the FMA displayed lateral steering mode be in roll direct? Same as roll alternate? Blank?
Probably NAV, HDG or TRK. Airbus AFCS is just an AFCS, only special thing about it is output; it doesn't go to autopilot servos but to FCCs. I suppose it doesn't care if its roll commands are obeyed by moving the spoilers and ailerons with constant roll rate or constant deflection. I suspect that AP doesn't work in direct law is because FBW has no control over pitch trim in it.
Originally Posted by Organfreak
There's always room for improvement, whatever the make of the aircraft.
Yup, but they don't come about just because someone has wished for them and they never come without a price.
Originally Posted by Lyman
That the stick shaker is a life saver
So are a parachute and a helmet but you won't see me wearing those when flying passengers.
Originally Posted by Lyman
is trained in approach to Stall syllabi
On the aeroplanes equipped with it!
Originally Posted by Lyman
and is found on your very own aircraft
Because during certification, her natural stall characteristics were found wanting so they had to be supplemented by the artificial means!
Originally Posted by Lyman
You fly a turboprop, a T tail, I assume. That is a complex platform, and in challenging conditions, I propose that your aircraft so equipped, is a safe one?
Safe aeroplane with totally unsafe natural stall characteristics. How about that?
Originally Posted by Lyman
the outcome may have been better if the stick turned into a buzzing snake in her pilot's grip?
BEA actually performed the study to determine what it felt like as the AF447 approached the stall:
Originally Posted by BEA final report on AF447, English version, page93
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. This angle of attack was reached at about 2 h 10
min 57 s during the accident flight.
What are the chances that the pilots that ignored 1G amplitude shake as the sign of impending stall would pay attention to "buzzing snake"? I hope this lays the notion of stick shaker being useful on A330 to rest.
Originally Posted by Lyman
The 330's Stall was entered in extreme fashion, quickly, and without the nose drop and falsely advertised Buffet from Stall that the Airframer sold the regulator on when begging for what you describe as "dispensation" from Shaker install.
See previous entry.
Originally Posted by Lyman
I am amazed that such a seasoned pro would continue to say that the shaker would have been of no use.
With a little help from the red warning at the bottom of this page, your posts amaze me no more.
Originally Posted by DL-EDI
In either case, wouldn't continued wrestling with the the controls suggest a bigger issue than how the logic works?
Depends on controls architecture. On some aeroplanes you may end up with split controls and each side flying just one elevator, completely independently of the other. Sounds fun, eh?
Originally Posted by DL-EDI
In a co-operative handover, does a Priority button even need to be pressed?
No.
Originally Posted by Lyman
a yoke equipped a/c cannot split command, mechanically, it cannot happen, and is independent of the sanity or skill of either pilot.
It can split. It can happen. It is not independent, especially in the wrestling over controls cases. Priority button is very neat way of taking the control away from the captain Gonenuts.
Originally Posted by Dl-EDI
I'm no aviation expert but, based on my IT experience, I'm not sure that algebraically summing two inputs is a particuarly challenging task for computers.
That's just what they do but it is very, very wrong way to fly an Airbus. Only one pilot can fly her at the time, be it left, right or auto, this feat is just there to ease the hairy control handovers, before PiC clearly designates who will fly.