Any updates on the Airbus lost in the Atlantic?

I just came across this item......

http://www.flightglobal.com/articles/2011/06/01/357394/stalled-af447-did-not-switch-to-abnormal-attitude-law.html

 

Well, they obviously have some inside information or they just made that up!

 

This is a prime example of "if it aint broke dont fix it" The more advanced these airplanes become the more screwed up they get. You can have the best in avionics and computers etc. etc. but they should just leave the good old, time tested, old fasioned cables from the yoke to the flight controls.

 

Yep! Just like the 777.

 

Based on the BEA report, and keeping in mind that I wasn't in that cockpit, the answer is: YES. He could have reduced back pressure on the side stick (or even pushed forward slightly), and flown the airplane out of the stall.

I think they had valid airspeed data for most the descent as well.

 

There has been much discussion about frozen pitot tubes preventing air speed inputs to the computers, resulting in the disengagement of autopilot and autothrust which occurred at 2h 10 min 05. This occurred just after a 12 degree left turn, although there is no indication or description in the preliminary report about what caused the systems to disengage.

That said, the report goes on to indicate speeds were being indicated on the PFD and ISIS.

Does this mean that the pitot tubes were not a root cause and that there was no loss of air speed information to the computers - or have I missed something?

The inconsistency I can't reconcile is that the report seems to indicate that flight speed data was being relayed to the instruments, but the VDR has PNF saying ""so, we’ve lost the speeds" then "alternate law […]" at 2 h 10min 16.

I'd understand if the air speed information was been incorporated into the report from the FDR after the fact, but the report does not simply indicate what the speeds were at certain times, but also that the information was being indicated on the instruments.

Again, have I missed something obvious?

CG

 

Yes, you missed the fact that the pitot system resumed providing valid airspeed information after about one minute.

They thought the speeds were invalid because they were so low, but it looks to me that the speeds were so low because the airplane was stalled (take a glance at the airspeed indicator in a stall sometime).

The sequence was, pitot tubes were blocked (most likely by ice), airspeed data became invalid. Autopilot and autothrottles disconnected.

The airplane went into alternate law when they lost airspeed indication.

While the airplane was stalled, the pitot system started to work again-- at least, that's what it looks like to me (I could be wrong).

 

Um, no thank you.

I filled my "boarding pass" on a demonstration flight with the Canadian Snowbirds after a series of admittedly benign 4.0 g banked turns.

I appreciate the clarification.

CG

 

No, more like the 717.

 

If I remember correctly, the 777 has cable connections to the outboard spoilers and the horizontal tail trim. Yaw control and pitch control when everything else is dead.

 

Don- That aircraft had a least three systems providing velocity data, the pitot system, the INS (ground speed) and the GPS (also ground speed). If the system determined the air data system was inop, Kalman had two other sources of speed data it could have provided to the aircrew, assuming Kalman weighting did not throw them out. Depending on algorithms, the INS and GPS could also provide airspeed base on altitude and last temperature data, also available from both sources.

So they may have been looking at velocity data from an alternate source, which they promptly disregarded as unreliable because how could a 300,000 lb airplane be going only 60 knots or so? Have seen 60 knots several times in a climbing F-15, but that aircraft was still controllable at 60 knots as long as you did not do anythig stupid.

Taz
Terry Phillips

 

Sounds very Boeing like.

 

I think we're roughly in agreement on this, although it reads to me that airspeed data became valid.

An internet acquaintance of mine who works on the 787 said that it has a "synthetic airspeed" display that it can show in the event of invalid airspeed data.

Unfortunately, these guys seem to have gone down the wrong mental path (by that, I mean that their theory of what was going on was not correct), which really started as soon as they lost the automation. With three reliable sources of pitch data, and reliable and operating engines, there is really no good excuse for failing to recover the aircraft.

One theory I have heard is that the Captain may have been concerned about structural damage to the tail. Of course, it doesn't appear that he verbalized his concerns, or that any of them did much discussion or verbalization of what was going on.

I was once in a cockpit under similar circumstances (fortunately a simulator). We were descending rapidly and out of control from around 15,000 feet-- I think maybe in a flat spin. It was really something to watch the altimeter spin down, and everything you try to do to recover the airplane have no effect, until you crash.

To make matters worse, or add a small bit of realism, I was taking a checkride, and failure meant I would have to stay at the training center for several more days (not pleasant).

Fortunately, I passed the checkride in spite of crashing! And from the toughest examiner in the system, at that time.

 

Early in the 777 program Boeing was chided for not being modern with a totally computerized system but management issued a very firm directive that there WOULD be direct connections to the afore mentioned controls. We didn't hear anymore derisive comments after an Airbus had an in-flight complete electrical power loss for several minutes.

 

I don't think there is any evidence that the control system would have inhibited recovery in any way, other than the fact that the airplane was way out of trim and the control system may have inadvertently put it there. They could have retrimmed manually, though.

Far more likely is the idea that the crew THOUGHT (incorrectly) that the automated systems would keep them from stalling.

 

Hello all,

I had not planned to return to F-Chat but I got some clarification on the autotrim issue and (as I've said) I'm a freak about solving mysteries and getting to the bottom of things so I'd figure I'd share now that I had reliable data.

I knew a buddy of mine was flying commercial after he left the AF but I did not know what or where. Through some friends I tracked him down and he's a 320 Captain. (note AF 447 was an A330) He had already read the report etc and said there were only 3 possible explanations:

1) Spontaneous coincidental mechanical failure of the autotrim (not very likely of course)
2) Pilot input
3) The autotrim did not 'freeze' as many have said, it just never moved. (got that?)

Here's the deal... If the autotrim was not disabled by the pilots and they pulled full back for 30 seconds it very well may have trimmed full nose up. The report clearly shows they applied nose down after that... but the plane did not re-trim. (as I assumed) I asked why... He said on the 320 if you apply nose down but do not apply enough to make the elevator move to a neutral or negative position, the plane will hold the trim. Had they ever moved the stick down long enough for the elevator to go neutral or slightly negative it would have returned to neutral and if they held down long enough the THS would have gone negative.

He said it was likely that the nose down mentioned in the report was so minimal that it had no effect.

He said, "this [the trim data] tells me basically they held the stick back all the way down."

Asked if he thought a full nose down would have saved them and he said that if you assume the plane auto-trimmed up, you could only assume it would autotrim down and that yes, a simple nose down or even if they had left it neutral the story would have ended differently.

I asked and he reconfirmed that last part, his guess was that even a neutral stick would have saved them.

That's all folks.

 

Did you ask him if it would have auto-trimmed down if, at the time of the full nose down, it was in abnormal alternate law or direct law?

 

The findings of this accident will actually be good news and bad news for Airbus. The good news is the aircraft was fully capable of recovering from the departed controlled flight condition, so the accident has to be ruled as aircrew error as the primary cause. Bad news for Airbus because you had very highly trained aircrew members who could not recognize what was happening to them from the displays at their command, and who consequently did not apply control inputs that would have regained controlled flight.

All the news for Air france is bad from any angle you approach the accident, aircrew error and failure to quickly change out a known faulty component.

A preventable tragedy, which is the sad part.

Taz
Terry Phillips

 

Yes, they do, and in the case of this one, it went off several times.

 

From an Airbus Captain in another forum........

 

(Kind of) Same with the 330 and 340s.

"As with the A320 series, mechanical signalling is used for the rudder and for the horizontal stabilizer trim backup."

From: "New Avionics Systems —Airbus A330/A340"
J.P. Potocki de Montalk
Airbus Industrie
http://www.davi.ws/avionics/TheAvionicsHandbook_Cap_30.pdf

 

So it appears that the bottom line cause that led to everything else was: insufficient pilot training? Looks like the airline is in deep doodoo.