pilotbraden
pilotbraden HalfDork
6/6/11 9:39 a.m.

The black boxes from Air France 447, the Airbus A330 that crashed in the South Atlantic, have been recovered. The following is an update from the BEA. It seems like a scary 5 minute descent to the water.

http://www.avweb.com/pdf/447may27report.pdf

The following is a letter from an Airbus A330 captain

Letter of the Week: Airbuses Fly "Like a Video Game"

I would like to offer my comments and perspective with regard to the Air France Flight 447 accident. I have been a A-330 captain since 2003 and have over 4500 hours in the aircraft. While many A-320 pilots undoubtedly have more series time, I believe this probably makes me one of the most experienced A330 pilots in the world.

When asked how I like the aircraft, I tell people that there is likely no easier airplane to take over an ocean, and that the systems design and presentation is superb. That said, the automation is more complex and less intuitive than necessary, and the pilot-aircraft interface is unlike that of a conventional aircraft. Most important with regard to this accident is the fly-by-wire sidestick control. The sidestick itself has a very limited range of motion, making inadvertent over-control very easy. Of even greater significance, the stick itself provides no "feel" feedback to the pilot. That is, unlike a conventional aircraft, the pilot does not get a sense through pressure of how much input is being sent to the control surfaces. The most important advice I give to pilots new to the Airbus is to treat the aircraft not as an airplane, but as a video game. If you wait for the sidestick to tell you what you are doing, you will never get an answer.

Taking into consideration that Air France 447 was at FL 350 (where the safe speed envelope is relatively narrow), that they were in the weather at night with no visible horizon, and that they were likely experiencing at least moderate turbulence, it does not surprise me in the least that the pilots lost control of the aircraft shortly after the autopilot and autothrust disconnected.

Let's keep in mind that these are not ideal conditions for maintaining controlled flight manually, especially when faced with a sudden onslaught of warning messages, loss of autofllght, confusing airspeed indications, and reversion to "alternate law" flight control, in which certain flight envelope protections are lost.

A very bad Airbus design feature is thrust levers that do not move while in autothrust. They are instead set in a detent which would equal climb trust in manual mode. If the pilots did not reset the thrust levers to equal the last cruise power setting, they likely eventually ended up in climb power, making it difficult to reset the proper cruise power setting and adding to what was likely already a great deal of confusion.

But the real problem probably occurred immediately after the pilot flying grabbed the sidestick and took over manually. Unfortunately, airline pilots rarely practice hand-flying at high altitude, and almost never do so without autothrust engaged. As a result, we forget that the aircraft is very sensitive to control inputs at high altitude, and overcontrol is the usual result. Because the Airbus sidestick provides no feedback "feel" to the pilot, this problem is dramatically compounded in this aircraft.

I believe the Air France pilot grabbed the sidestick, made an immediate input (because as pilots, that's what we tend to do), and quickly became quite confused as to what the aircraft was truly doing. This confusion likely was exacerbated by fixating on airspeed indications that made no sense while trying to find a power setting with no airspeed guidance.

When transitioning from autopilot to manual control at altitude in the Airbus, the most important thing to do at first is nothing. Don't move a thing, and then when you do, gently take hold of the sidestick and make very small inputs, concentrating on the flight director (which, in altitude hold, should still have been providing good guidance). Of course, this is much easier said than done with bells and whistles going off all over the place, moderate turbulence and a bunch of thunderstorms in the area. As I said before, treat it like a video game.

So why did the Air France pilot find himself at the limits of sidestick travel, and then just stay there, maintaining a control input that simply could not logically be correct? When things go really bad and we are under intense pressure, it is human nature to revert to what we know from previous experience. Remember, the Airbus flies like no other aircraft in that the sidestick provides no feedback to the pilot. It is a video game, not an airplane.

I believe the Air France pilot unintentionally fell back on all of his previous flying experience, in which aircraft controls "talkedF" to him when he moved them. Distracted by many confusing inputs, he instinctively expected to be able to control the aircraft by "feel" while dividing his attention to address other matters. I've seen it happen in the simulator, and in an Airbus this is a sure way to lose control of the aircraft and is possibly the most dangerous aspect of Airbus design philosophy.

One last note: Airbus pilots often claim that the aircraft "can not be stalled." When the flight controls are in "normal law" this is a reasonably true statement. However, in "alternate law," as was the case here, stall protection can be lost. If we ever practiced this in the simulator, I don't remember it.

Lest anyone think I am blaming the Air France pilots for this accident, let me be clear. Despite all of my experience in the aircraft, I am not the least bit certain that I would have been able to maintain control under the same circumstances. I do feel certain that were you to spring this scenario on pilots in a simulator without warning less than half of them would have a successful outcome. Safely flying the 320, 330 and 340-series Airbus requires something of a non-pilot mindset.

Name Withheld

Editor's Note: We have spoken with the writer of this letter to confirm his identity and honored his request for anonymity. For another analysis of the trials and challenges of flying an A330, be sure to listen to Friday's podcast with airline pilot Jason Goldberg.

mad_machine
mad_machine GRM+ Memberand SuperDork
6/6/11 10:21 a.m.

scary stuff to build a plane that has no feedback... what were they thinking?

aircooled
aircooled SuperDork
6/6/11 10:21 a.m.

Let the pilots fly and drivers drive, I say.

The less you let them fly, or drive, the less they will be able to.

It seems like when Airbus designed those planes, they looked at all of the NTSB reports for crashed and noticed that almost all of them had "Pilot Error" noted as a major cause, so they figured "Hey, lets just remove the pilot from the equation as much as possible". What could go wrong?

The Airbus, to me, is like the new Mercedes, which might as well have the slogan "Don't worry if you can't be bothered to pay attention to your driving, you Mercedes will take car of it", what could be wrong with that.

z31maniac
z31maniac SuperDork
6/6/11 10:57 a.m.

So we have force feedback in a driving wheel for GT5, but the French couldn't handle that for multi-million dollar aircraft with hundreds of lives at stake?

Certainly pilots have mentioned this?

integraguy
integraguy Dork
6/6/11 11:14 a.m.

z31maniac...

AirBus is built by a EUROPEAN consortium (sp?) of aircraft companies, including those with British, French, and German home offices. To say "....that the FRENCH couldn't handle that...." leaves out the British, Germans, and any other company/country involved.

As cars and trucks become more and more "drive by wire" accidents like this will occur, albeit on a smaller scale.

ransom
ransom GRM+ Memberand Reader
6/6/11 11:39 a.m.

When I think of autonomous vehicles, and the idea of being a passenger in one, the worst-case scenario of realizing that things have gone wrong and that the controlling mechanism is about to get me killed (and that I can't do anything but watch it happen) springs to mind.

And it is truly terrifying. But...

It's hard to defend my terror of the automatic if, on average, it is safer than manual control. That is, it's hard to insist that I get to retain control because I find it a terrifying way to go, if the reality is that I'm more likely to kill someone else because I'm not as reliable as an automated system.

That being said, it does seem like in this case, a "best of both worlds" arrangement which provided suitable feedback to allow pilots a better chance of regaining control seems a no-brainer. I don't know what combination of technical hurdles, weight, cost, etc caused them not to pursue this path.

wlkelley3
wlkelley3 Dork
6/6/11 11:53 a.m.

Having done a few helicopter accident investigations and studied aircraft accident investigations, there is a slight misnomer on the term "pilot error". There are basically two types of pilot error. One is obviously the pilot messed up. Totally their fault. The other one (and most prevalent) is exceed capabilities. Now that can be broke down into two levels also. Exceed the pilots capability and training. Exceed human capability.

Modern aircraft is seeing more and more computerization to take over flying. All in the name of increasing safety and reducing pilot workload. Then there is a tendency to keep on adding things since the pilot workload is decreased, thus increasing pilot workload in the end because he has to do more. Modern pilots are computer programmers with pilot capability. It does make for safer flying and more accurate flight envelopes when everything works right. But with certain series of failures will lead to catastrophic events. After all, it's kinda difficult to pull over on the next cloud when something goes wrong. But in percentages, there are less aircraft accidents per flights than car accidents. Just more catastrophic in aircraft, it's a long way down.

aircooled
aircooled SuperDork
6/6/11 12:10 p.m.

Just to expand on my "pilot error" comment. That was meant to imply the designers miss-interpreted the note of Pilot Error.

Realistically, pretty much ANY accident will in someway be Pilot Error, for the simple fact that the pilot is ultimately responsible for the safe operation of the aircraft. That of course include ignoring regulations / rules in the interest of safety. E.g. If plane flies into a storm and the storm takes it out in someway, well certainly the storm caused the issue, but the Pilot probably had the option (and the responsibility if they thought it was necessary for safety) to fly around it, or, ultimately, not fly at all.

An interesting example of this was an accident report I read about a bombardier that crashed in 2004. The main cause was obviously the pilot being an asshat, but it is interesting to note that as the issue develops (they were flying the plane at it's service ceiling for no reason) they choose to stay at their assigned altitude waiting for clearance to descend rather then ignore the controller and just descend to save the engines (which may or may not have save them of course).

Here is the accident report. Interesting, and somewhat frustrating in it's stupidity, reading. Hey at least they didn't kill anyone else.

http://www.ntsb.gov/events/2005/Pinnacle/exhibits/CVR_Factual.pdf

(note, this links directly to a pdf doc)

benzbaron
benzbaron Dork
6/6/11 12:30 p.m.

I read an article in the WSJ and it sounds like the pilots fought the controls of the plane once disengaged from auto pilot. I guess the air speed indicators were faulty and and the plane basically fell out of the sky from lack of lift. It sounds like the way to maintain air speed and lift is to actually nose the plane down and change some of the 30000feet of altitude into air speed which give the plane lift. The thrust alone of the engine isn't enough to give the plane enough lift to power out of falling out of the sky. Sounds like the planes nose was pointed up the whole time while falling out of the sky and instead of nosing down and powering up the engine the pilots kept the nose up and basically tried to use the engine to stabilize the altitude and speed. A similar incident happened in Buffalo where a prop plane started to stall out when landing, but the plane automatically noses down when a stall warning is issued. The pilot fought the controls in Buffalo to maintain altitude and ended up stalling the plane the stuffing it. I guess the idea of nosing down and increasing engine thrust to stabilize a plane in a stall situation is standard operating procedure and deviating from it can cause catastrophic events like what happened in these two incidents.

Osterkraut
Osterkraut SuperDork
6/6/11 1:17 p.m.

The best planes have pointy vertical stabs.

Gearheadotaku
Gearheadotaku GRM+ Memberand Dork
6/6/11 10:41 p.m.

I'm no pilot, but whenever I hear a pilot speak about an airbus, they never have anything good to say. Lack of feedback is the biggest complaint. Saw a TV interview years back. Pilot said "I can fly a 747 with a cup of coffee in my hand, knee resting against the stick and and know exactly what that aircraft is doing. In an Airbus I'm just a passenger like everyone else." If the pilots don't like to fly in them, how am I supposed to feel as a passenger?

Kendall_Jones
Kendall_Jones Reader
6/6/11 10:57 p.m.

I can only imagine the terror of those final few minutes. F that S. I was on a flight to india where the turbulence was so bad that plane dropped so hard & fast that one guy was seated (not buckled) and flipped over his seat into the person behind him. That was done in an instant, those poor bastards had minutes of that.

Kendall

gamby
gamby SuperDork
6/6/11 11:07 p.m.
Kendall_Jones wrote: I can only imagine the terror of those final few minutes. F that S. I was on a flight to india where the turbulence was so bad that plane dropped so hard & fast that one guy was seated (not buckled) and flipped over his seat into the person behind him. That was done in an instant, those poor bastards had minutes of that. Kendall

Yeah--that pretty much tops my list of fears.

I can't think of a scarier way to go.

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