Originally Posted by CONF iture
Starting with the autotrim under manual flying ... who needs anything like it ?
To have to trim under manual flying has always been part of the pleasure and understanding of what it's all about piloting.
Raise your hand if you thought that an autotrim under manual flying was a necessity (Remember your time on the other types ...)
Auto-trim is necessary in order to implement a load factor demand pitch law. The aim is to get a constant path free stick behavior, i.e. a path independent of speed, thrust or configuration. I didn’t try it myself but it could well be that with a sidestick controller such a behavior is better and preferred compared to a more conventional “trim to speed” system. However, you need to add protections at both ends of the longitudinal flight envelope if you want the system certified for commercial operations, hence the high speed and high angle of attack protections.
Problems appear at less than Normal Law due to protections removed but then basic certification requirements don’t apply. You are left with stall warning only in ALT 2 law.
AF447 has been autotrimmed to the max up position under STALL WRN ... something is awfully wrong here !
At least, leave to the pilots that responsabillity if such was really their wish ...
100% agreed.
There is something paradoxical with this new “space aged” flight control system. Certainly the airplane is easy to hand-fly in normal mode, perhaps a bit more “touchy” in alternate mode where default gains are used and again more sensitive in direct mode. Easiness has been used as a commercial argument to customers, suggesting savings in training. We, old pilots, having used “dinosaur” flight control systems regularly disconnected automation, even at altitude, when we felt we could do better manually, which was often the case. At the time, we were never really in need to “update” our skills in this respect and today the background experience is still there.
Now think about the current situation of young pilots. They are just given a taste of direct law in the sim, not necessarily at altitude, a few minutes once every 4 or 5 training session and the rest of their hand-flying life is Easy Law, follow-the-FD-it-is!!! Yet, they are supposed to have a decent level of flying skills when they are abruptly passed a less than optimal system. The paradox is that making the task easier erodes the necessary skills i.e. does not systematically result in enhanced safety.