AF 447 Thread No. 10

[gums]

Good analysis Retired and 'bird.

Without a "brain recording" we shall never know why the pilot kept pulling back. And I don't agree with 'bird about roll PIO and such. May have been there, but not to any serious influence versus the constant back stick.

If there is one good thing about the 'bus and our primitive system in the Viper, it was that HAL would use every control surface available to achieve the trimmed gee ( ours could be trimmed, but the 'bus was one gee all the time, corrected for pitch attitude). So simply relaxing the stick pressure would let HAL do what he was supposed to, allowing you to figure out what the hell was going on.

Another poster provided an excellent discussion of AoA WRT mach and altitude and such. But I am personally here to tell you that our primitive system handled the problem really well. We never exceeded the AoA limits while hard maneuvering, and the only way we got into a true "deep stall" was to hold a high pitch attitude as our energy decayed faster than the control system could get the nose down. Sound familiar?

Gotta go. Dodging hurricane in Florida.

Addendum:

It still distrubs me to see some pilots here that don't seem to understand how their jet flies. The new jets, with all the augmentation and such, may appear to be real easy to fly. Then you look into all the control laws and such and see what HAL is doing.

What do you do when HAL gives up?

I can't find one commercial jet with FBW or basic/advanced augmentation that doesn't fly like we old dinosaurs were used to.

As several here have pointed out, the 'bus is a basic "direct law" until well up in the air or in the "flare" ( not sure what the flare mode does, but whatthehell).

Ours was "direct" until weight off wheels. Then it was blended AoA, pitch rate and gee command until gear was fully up. Worked for me, and thousands of fighter pilots that have flown the jet since 1973.

I have a lot more confidence as a SLF after reading some of the "war stories" here from the professional pilots than I had three years ago. But make no mistake! If I am on board and you are the PF/PIC/AC or whatever, I shall be back there analyzing every move you make, heh heh.