I'd like to answer
this question:
Quote:
Originally Posted by silverelise
SLF question about ditching in the Airbus (mods feel free to move somewhere more apt if needs be).
Do you have to override any of the flight management systems or change to one of the different "laws" in order to get the aircraft near the ground without being in a landing configuration (eg. gear still up etc).
Well, if you've heard about Airbus' "Flight Control Laws", you might have read at a bit more on it. Some of the basics ideas are certainly available on-line.
The difference between conventionally controlled and Airbus fly-by-wire could be summarized (somewhat simplified) thus:
- In a conventionally controlled aircraft the flight controls deflect the control surfaces with a fixed ratio, and aerodynamic forces move and turn the aircraft. It is the pilot's responsibility to compensate for varying conditions.
- in an Airbus FBW aircraft the flight controls tell the computer how the pilot wants the plane to move and turn, and the computers deflect the control surfaces in such a way that it moves and turns exactly as requested, with the computer(s) compensating for varying conditions.
That said, any aircraft will fly wherever the pilot tells it to fly, including straight into a mountain or smoothly down onto the Hudson.
It will give you a warning when you get too low to the ground with the gear and/or flaps retracted, or approach terrain too fast, but all modern airliners will do that, it's part of the EGPWS, and not Airbus-specific. For a forced landing/ditching some or all of these warnings can be disabled to avoid distractions.
What someone has pointed out, the ability of the Airbus to maintain the bank angle (even automatically return it to 0 if it is below 5 degrees) may have helped a bit with the ditching, but in relatively calm conditions the differences to, say, a 737 shouldn't be dramatic.
Cheers,
Bernd
...With
this quote:
Great Job!
This is really a great piece of airmanship work and although cabin crew deserve a word of gratitude (their work was also so important to evacuate all passengers alive!) I must tell you that, I am fascinated by the great job, done on the cockpit.
Yesterday I went to bed still frilled by the outcome of that accident and I have tried to make the exercise of positioning myself in the seat of that captain...it wasn't easy, I must concede. Those who are not pilots and are not familiar with flying a powerless A320 have no idea of the complexity of handling that "glider" (together with the completion of check-lists and the handling of the situation with the chief purser, ATC and Pax.). In the flight Simulator, at Green Dot Speed, one gets a rate of descent of approximately 1800/2200' per minute and the the simple fact of trying to "recover" about five Knots, for instance, will result in the increase of that rate to 2500/2800' sometimes 3000' per minute! Further, as far as I remember, one would be receiving partial hydraulic power trough windmilling and the RAT (minimum speed for power 140Kts) so Slats/Flaps selection would have to be done with parsimony, (at the right altitude, to allow for profile upsets) would come slowly and would influence not only the profile itself, but the Flight Controls behavior also...
Flight Simulators seem to be not prepared for the training of ditching maneuvers, therefore we usually train double engine failures (sometimes with ditching preparation) and subsequent landing on a field witch require planning for touching down on the first segment of the runway. In the present Hudson River case, the "runway" was long, but time was short. No time for mistakes, no second chance for a perfect landing.
They have done well. More than that, they have restored faith on our profession!
Congratulations on a Job Well Done.
Fly Safe
Įgua d'Alte
...and would like to add, that:
One can always look for mistakes, bad decisions, alternatives and "luck", with all the time of the world, behind our desks, with a glass of good wine in our hands...
When a once in a lifetime occasion like this, happens to a Pilot, he/she has to take a decision that may turn to be a good or a bad one. I do think that Captain
Chesley Sullenberg 's early and prompt decision is the key for his success. Could he have done more? Could his First Officer have done more? Maybe. As far as I am concerned I do think they have done great!
And NO. Those computers "don't fly for you" in a double engine failure! You have to fly the aircraft "the old fashion way"! A320's (generally) go to a "direct law" mode in case of dual engine failure, which includes now, manual trimming of the aircraft (throughout the trim-wheel) and direct input control of the flight control surfaces of the aircraft. That's why we all should encourage Airline Pilots to fly general aviation, single engine and gliders as a hobby. But that's another story...
Fly Safe
Įgua d'Alte