"Airbuses fly like a video game ....."

[dbcunnz]

"Airbuses fly like a video game ....."

Most logical explanation I've heard to date .... and maybe now they'll consider going back to a system pilots can fly when all hell breaks loose ....

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 aeroplane 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 aeroplane, 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 thrust 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 aeroplane.

I believe the Air France pilot unintentionally fell back on all of his previous flying experience, in which aircraft controls "talked" 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 "cannot 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

[scaber]

An interestimg read Doug. Thanks for posting it.

[nzav8tor]

I don't think the eventual accident report will put it as succinctly.

[Splitpin]

Thanks Doug, its always nice to read something with a certain amount of authority in it for a change......nothing worse than speculation from the uninformed....and as nzav8tor said..."I don't think the eventual accident report will put it as succinctly"

Very interesting.

[Ian Warren]

Arbust Again , damn Video

[Charl]

The information and disinformation will come thick and fast now, as the various parties look at the size of the looming compensation claims.
http://www.stuff.co.nz/world/europe/538627...nce-crash-probe
Hats off to the investigators for finding the black boxes and wreckage after all this time.

[Ian Warren]

QUOTE (Charl @ Aug 4 2011,9:07 AM) <{POST_SNAPBACK}>

Hats off to the investigators for finding the black boxes and wreckage after all this time.

Little understated , it dose show you that technology works .
I think all passenger types should keep away from FBW , least under manual control as pointed out you feel the force feedback and it is quiet heavy doing a 15 Deg. turn and thats what you as the pilot is trained to do.

[cowpatz]

An interesting read Doug and his experienced views are similar to my own thoughts on the Airbus logic.
Unlike Boeing the basic design philosophy is reversed. Boeing assume that pilot input is correct and automatics are there to assist.
The basic Airbus philosophy assumes that the aircraft knows best and that any pilot input is through the automatics (and needs to be validated).
The basic feedback mechanisims that nearly all pilots experienced during training are no longer present.
1. No Q feel through the sidestick (control feel)
2. Autothrottles that dont move.
3. Autotrim
4. Pitch augmentation (No pitch change with thrust or L/D changes - flap/gear)
5. Very little engine or airframe sound. (Fewer seat of the pants clues as to power setting or airspeed)

Of course training ensures that pilots become familiar with the various aspects of a particular aircraft type and the Airbus is no different.
The basic problem is not with a normal line flight but when things start to go wrong. The Airbus flight law logic (at least 4) is extremely complex and not all of the degradation modes are routinely trained or even fully understood.
When I first started flying airliners an older and wiser Captain once remarked to me "Son you will soon need to be a lawyer to fly one of these things...." . This was in the days before Airbus and he was referring to the increasing complexities and litigious nature of aviation law, however given the Airbus control laws logic, he is still correct in his view, albeit in a different way.
The real problem is when things go wrong. The more the systems complexity, interconnection, interoperability, interdependibility and sub modes that there are the worse a significant non normal event usually becomes. Take a look at the recent QF A380 incident near Singapore. There were no less that 50 ECAM messages to deal with along with numerous electronic checklists some of which needed to be modified or ommitted due to the effect the resultant configurations may have on other systems or overall aircraft controllability. There were 5 of them on the flight deck. 1 flying with the others working through confusing and complex checklists. Now add into this mix a degradation in control law, altitude, night time, adverse weather and turbulence. All factors that almost gaurantee an unsuccessful outcome.

At the end of the day in a non FBW aircraft when it all turns to custard basic primary training takes over. Disconnect the AT's and AP pull or push on the contol column and the elevators will deflect proportionally as will the ailerons and rudder. Set the power by feel (comes instinctively) and you will hear it and feel it.

Of course there is no denying that FBW is the way of the future(even Boeing use it but still largely preserving their fundamental philosophy) but what will happen when the new breed of pilot that works his way through the system (with no non digital flight controls experience) hits the line. A pilot who has never had to recover from a stall (because it will never happen). Who has never had to recover from an unusual attitude or overspeed (because it can never happen). Where is that basic flight skill going to be when it's needed?
This should never happen? The crew of AF447 where probably thinking that as they plunged out of control into the sea.

[ZK-MAT]

That comment sounds like something I read on Flight Level 390's blog some time ago... it would be interesting if it was. I'd recommend http://flightlevel390.blogspot.com/ as a well written day by day account of an experienced Airbus Captain. Just make sure you have time to digest the site as you will probably, like me, get distracted and spend too long reading.

I've just done a search of 447 on that blog and cannot find the above article so I suspect that I read it elsewhere - but the entries here at http://flightlevel390.blogspot.com/search?q=447 make for good reading

[Charl]

Excellent blog, thanks for the link.
I read top to bottom, just as you warned!
I do find myself gagging on the topic of AF447, and in particular what the media do to the likes of
"retired pilot and American hero, Chesley "Sully" Sullenberger"
There's an incredibly extensive Air Accident Investigation underway.
It will come up with some findings, and when it does, that will be the time to comment.

There will most certainly be revised training requirements for pilots of future airliners.
Human-as-monitor-of-automated system, is very different from bugs-in-your-teeth magnificent man in his flying machine.