Actually, there are three modes: "normal", "alternate", and "direct". I forget the specifics of how the displays work, but there is an indication when the aircraft is no longer is "normal law", which yes, does prevent the pilots from exceeding the normal flight envelope. Alternate and direct law provide increasingly less envelope protection, with "direct" providing nearly zero protection.

The averaging of the two controls is dumb, though. Pilot A: Left! Pilot B: No, right! Computer: Ok, straight!

It's worse than that, Jim

There's at least one more: 'direct' law. In normal law (which is all you'd ever expect to see, unless there had been multiple failures in redundant systems - pilots only encounter 'alternate' law in the sim) it is (almost) impossible to exceed the safe envelope. So heaving back on the stick (while bad practice and utterly alien to anyone who'd learnt to fly on, say, a Cessna) is normally quite safe - but in this case it was fatal. The change from normal to alternate law is shown on the flight computer, but there were a lot of simultaneous announcements when the problem occurred - before the recovery of the black boxes, the only data was from the in flight transmission of engineering data which showed about 80 (IIRC) warnings in a few seconds.

You're quite right that only one pilot should be handling the aircraft at any one time - which is why the behaviour of the sidestick controls is not normally a problem. But this does highlight the lack of tactile feedback for the non-handling pilot, which those brought up on Boeings tend to dislike.

Despite all this, it should have been a non-event. All pilots are supposed to have memorised the appropriate settings of power and aircraft pitch to be used in the event of failure of the airspeed indication, which would have allowed AF447 to simply fly through the cloud until the pitots unfroze and all returned to normal. No-one has come up with a very satisfactory explanation of why the handling pilot reacted as he did.

Pilots *can't* exceed the flight envelope under the normal law; that's what it is for. (The autopilot can't exceed the envelope either; if it tries under normal law, it's automatically disengaged and a warning horn sounds.)

Alternate law exists for cases in which the ship's computer system isn't getting enough information to be certain it can fly the aircraft safely -- as, for example, in the case of pitot tube icing, which was what happened here. It's the computer's way of telling the pilot "look, I'm not sure I know what's going on correctly, so you'd better take over."

I'm not sure whether there's a clear indication in the cockpit of when the flight control law changes, but it would very much surprise me if there weren't; after all, switching off part or all of the fly-by-wire system is going to significantly change the aircraft's behavior, wouldn't you say?

But I *am* sure that Airbus doesn't deserve blame for the crash, not least because Boeing's fly-by-wire aircraft use a very similar arrangement for graceful degradation of that system in case of malfunction or untrustworthy data inputs. Judging by the transcript, the fault clearly belongs to Bonin, who either wasn't properly trained or who failed to keep his head in the situation, at the cost of over two hundred lives including his own.

It actually has more than two modes, depending on what systems are available. In 'normal' the computers shouldn't allow you to conduct manoeuvres that will depart from controlled flight, e.g. it won't let you stall, if you pull fully back on the stick the computer will only let the airframe achieve the AoA for maximum lift no more. Effectively the pilots are allowed freedom of operation inside the safe flight envelope, the computers prevent the aircraft going beyond that.

In 'alternate' mode, recognising that some systems have failed and that it's unable to provide full flight envelope protection the aircraft reacts in a more traditional way, obviously it's important that the pilots recognise this.

Dual control inputs, yes, otherwise it's a bit pointless having two pilots, I did have the whole thing explained to me a while back, I can't remember the exact details but I'm fairly sure there's an over ride so one of the controls can have primacy.

That is in fact unfair.

Of COURSE a plane out of autopilot is in a different regime and I am sure they were aware of what not being in normal law meant - theoretically. Its probably in the manual somewhere.

The fact is they were not awarer - or one of them was not aware - that it applied at this point, and they seem to have displayed no sense of being trained in its use.

there is a little of blame attached to airbus..the sticks not being tied is one..but its mostly a terrible lack of training and a terrible casualness when faced with a situation outside the normal..as if they relied on the plane to fly itself out of trouble when it had told them it couldn't.

And that's fair and square in the court of ALL modern pilots who simply don't fly seat of the pants planes enough - if at all - to understand what the instruments put together are telling them.

Or at least fly enough emergencies in the simulators to effectively give them that experience.

Uhh come again?

Humans took over a plane and crashed it, and that's your reason why humans should be able to manually take control of plans?

I'm not disagreeing but this article dosen't seem to help your case.

But

I read in another source if the "Pilots" had switch the Autopilot back on when the pitot tubes started working the computer would have sorted it out and had the plane flying true in seconds.

Airbus needs to work on their Autopilots work- there was another crash in Russia of an Airbus when some pilot let his kid fly the jet (commercial) and the kid "partially" disengaged the Autopilot and there was no warning. Plane impacted the ground at a high rate of speed. Ground won.

I wonder how good the Autopilot is on the A380 .................

and also....

... the LOT pilot who did a superb job of putting a 767 down at Warsaw when its undercarriage failed to come down.

http://airpigz.com/blog/2011/11/2/2-videos-lot-767-lands-wheels-up-in-warsaw-poland-11-1-11.html

The second video, taken from outside the airfield, catches the touchdown perfectly. The pilot put it right on the threshold with the exact amount of flare to grease it on. Its hard to imagine how it could have been done better.

I hear that, like Sully, he is a glider pilot...

@Tony

The good news is that Capt Burkill got his job back at BA and is back flying 777s. Highly recommend his book "Thirty Seconds to Impact".

Not miraculous, just down to damn good flying.

the airbus's avionics had as much to do with the successful outcome of us1549 as the undoubted skill of the pilots. the avionics "flew" the plane -- keeping the optimal angle of attack until the last few seconds -- while the pilots figured out where and how they'd get the plane down as well as run through the emergency ditch and shutdown procedures in much less time than these procedures need. if the pilots had to control the plane all that time as well, there was a good chance something would have been overlooked in the tiny amount of time they had to do anything. so we'd have been talking about pilot error being a contributing factor in the loss of life from that one-in-a-million freak event.

"...the crash of a fully functional commercial airliner..." Part 2

Okay then, let me be even more emphatic about the distinction between Airbus and Boeing:

Observation 1: *Most* (significantly more than 50%) Airbus major crashes involve aircraft that are essentially in good mechanical condition in the millisecond before impact.

Observation 2: *Most* (significantly more than 50%) Boeing major crashes involve aircraft that are already significantly damaged, mechanically, long before they hit the ground.

Based on everything I've seen, I strongly believe that the two observations above are in fact true. I'm not saying one cause of disaster is better than the other. But the root causes appear to have an obvious divergence. Not "all", just 'most'. Downvote me all you want. Facts is facts.

Flight 447 is just the latest in a long sequence of famous Airbus CFIT incidents.

I don't see any facts

Citations please? Rather than your "gut".

Stick priority.

If both side sticks are moved at the same time an aural warning "dual input" is given by the aircraft.

In addition to this, there is also a visual warning light on the glare shield, just below the pilots' eye line, that illuminates to indicate that the other pilot is making control inputs.

Pressing the red button on the side stick gives that stick priority and cancels out the inputs from the other stick.

@b166er

Wow, you should be an aircraft systems designer - no-one ever thought of an altitude display, at least not until 1904. They knew their height and they knew they were descending, what they were (apparently) unable to recognise was that the plane was stalled and no amount of pulling back on the stick and firewalling the engines was going to change that.

"E.g. synchronising joysticks should not be necessary as only one pilot is ever needed on the yoke at a time, but it *should* be a requirement that BOTH pilots are involved in transferring control from one position to the other: it should be impossible for either one to just seize control of the plane without the other pilot even knowing about it. THAT is poor interface design."

Did you think about this before writing it? Just wondering how your excellent system will cope when the plane is in a crisis situation and the person who was flying the damned thing has passed out/had a heart attack/is otherwise incapacitated and unable to nicely pass on control to his co-pilot? Would you be bleating about the stupid requirement for BOTH pilots being involved in transferring control then? The current design is fine in principle (though not so sure about the averaging of inputs) - it just requires that 2 people talk to each other (which, according to other posters, is standard practice) in order to work out that control is being passed on and to whom.

As for the rest of the rant, do you really think that anyone should be able to just walk in and fly a plane? That it should be so easy that a child could walk in and go "yup, got it!"? Pilots are quite well paid - and rightly so - because they have (or are supposed to have) specialist skills in, and a lot of experience of, how to fly planes, including how to handle emergency scenarios. In fact, they are paid to read and understand those manuals you complain about - it's called "knowing what you're doing" and is quite important in most jobs.

It seems that these days the pilot's job is not much to do with the normal running of the plane - they seem, mostly, to do that pretty well themselves - but to take over when something unexpected happens. The pilots involved here obviously weren't up to that job.