THS trim in Airbus laws
@ Conf
Way I read it is that the 'bus is primarily a gee command, so pulling or pushing commands the gee. Not like the gee command we had in the Viper, which had an AoA limit input, but a one gee command corrected for pitch attitude. So at any attitude except zero, the gee command is less than one gee.
I shall admit that pitch rates and gains are in the mix, but not AoA unless in the primary control law. And this disturbs me.
No doubt that the THS trim logic "helped" to keep the nose up attitude of the jet all the way down. Even releasing the stick would have kept the THS full nose up, and the BEA report mentions this aspect of the flight control laws.
I highly respect all the "heavy" drivers here, and I have learned a lot from the last two years of dialogue. I agree with Bubs and JT, et al, that the Captain could not figure out how the jet got to its condition without going thru the whole sequence. Just ran outta time.
I would not expect the average "heavy" driver to figure out the problem in a few seconds. No offense to most of you, but realize that the two folks up front were born and bred in the 'bus, and "you can't stall this thing", right?
I shall still maintain my position that the 'bus control laws need a heavier emphasis upon AoA, much like the B777 laws I saw in Turbine's link. It is not hard for HAL to see the AoA inputs and use them to help with the flight director displays and the "protections", regardless of the impact pressure on the pitot tubes. There are too many sensors on the jet to use for graceful degredation, IMHO.
As in my last post, I see a super aero design in the 'bus, and it has no pitch co-efficient problem that results in the classic "deep stall". In short, the jet would have recovered given the proper control commands. But ya gotta realize what is happening, ya think?
Lastly, I doubt that the current 'bus drivers will ignore the AF447 incident's lessons. YOU CAN STALL THE THING if in a reversion control law. If AP disconnects then hold what ya got for a while until you figure out what is happening. Don't depend upon HAL to correct for any of your incorrect commands, but think like you are flying a Cub or Cessna. And the beat goes on.