Originally Posted by BOAC
- bottom of P90
Thanks, I missed that
Seems that someone at BEA messed up by providing ADR switching traces twice, instead of ADR and IR switching. They have time to fix it in final. As there were no IR failures or disagreements recorded, seems that switching of RH IR source from IR2 to IR3 wouldn't make a difference to displayed attitude.
Originally Posted by gums
For example, observe the Viper or Typhoon at your next airshow ( two FBW jets). Note how quickly the jet stops rolling. Lag? Yep
Did just that this summer at Zeltweg. Couldn't help but notice that both of them are combat airplanes, implying that they're on the opposite side of stability/maneuverability spectrum compared to passenger transports. If maneuverability is primary design concern, it's easy to reduce control lag by installing powerful hydraulic actuator. If not - weaker one will do just fine, it will be lighter, will strain hydro system less and require less beefing up of the structure it is attached to. That's why AF447 elevator traces shows gradual reduction from full nose down when forward stick was applied and not instant stop-to-stop wham.
Originally Posted by gums
Why ignore the AoA sensor inputs for stall prevention/ stall indications/displays?
Stall prevention - with pitot clogged there is no way for ADC to discern whether AoA or airspeed is faulty so it proclaims itself unreliable. With all three ADRs out, to reduce the risk of wrong protection kicking in, air data based protections shut off and leave the problem for intelligent beings to solve. That's basically what is meant by very technical term "Flight control laws"
Stall indications - it wasn't ignored. It worked properly.
Displays - no legal requirement for AoA displays to be fitted. With thousands of airliners flying safely every day without them and dozens of crews solving UAS just by reference to attitude and power, I don't find the logic behind not requiring AoA gauge in cockpit faulty.
Originally Posted by gums
Is the 60 knot speed doofer a poor design implementation versus a simple weight-on-wheels "switch"?
Not quite. Since you have to introduce ADR input into stall warning system to cope with Mach effect on critical AoA, having 60kt cutout is actually simpler than adding WoW input and with it another possible failure point.
Originally Posted by gums
The U.S. Navy jets had a full time AoA display called an "indexer" that told you to lower the nose or raise the nose.
Thanks for the info. On PC-9 indexer comes alive only when gear is lowered, I assumed it is just for landing on every military airplane.
Originally Posted by gums
I always wonder why the new airliners don't have a HUD.
I am afraid that we get new equipment only if it makes economical sense to someone in charge. I have Head-up Guidance System in my Q400 because it was cheaper to graft IRS and HGS on her to make her CAT3A capable than to develop autotorque and autoland-capable autopilot.
Originally Posted by gums
Sheesh, that HUD will spoil your crosscheck in a hurry, and it takes lottsa discipline to include the steam gauges.
Not to mention your landings will become more precise and softer with the help of the little birdie and then one day you'll be all f-ed up when your HGS gets MELed and it's back to switching between head down and up on landing again.
Originally Posted by jcjeant
Pilot handling was not exactly my point ...
Why? Pilot handling is exactly what put AF447 into trouble.
Originally Posted by jcjeant
For the Airbus when pitot tubes clogged you loss airspeed indication (visual) and also a important data needed for the automation system .. and that is the most important point (design of the automation system)
It would be important if A330 is impossible to fly without automatics. Well, it was designed to fly with computers and sensors badly shot up. It's not heuristics but many thousands of hours spent on carefully designing and testing the plane.
Originally Posted by jcjeant
I think (by what I read about reports and experience backup) that this event no deserve to be in a investigating entity archive
Reading the description, it could be either hitting the low G protection at -1G and that makes absolute hell of cabin even with everyone strapped in or serious failure of flight controls system. Where I live either option is heavy incident, will leave massive traces on QAR that would be picked up by the FDM so non-reporting would result in tea without biscuits and it has to be investigated by government appointed investigation commission.
Originally Posted by jcjeant
he was no more a pilot .. he forget he was a pilot ..
Since you say so, is this applicable to the case we're discussing, too?