Air France 447

Posted on 05. Jun, 2009 by in Featured

1. “The pilots flew into a level 5 storm.”
2. ”The auto pilot failed; at 35,000 the pilots would have their hands full.”
3. “The pilots may have stalled in turbulence. The high altitude stall would explain the break up.”

What is the common theme? Pilot error; it is being put forth subtly and not so subtly, through leaks and “bulletins”. The flight data recorder and cockpit voice recorder have not been recovered and yet the underlying thesis is; no matter what happened it was ultimately pilot error. Pilot error is the easiest way to make this go away with the smallest impact on governments, airlines and aircraft manufacturers.

There is a big problem with this thesis, two actually. It does not explain the flight control and attitude computer failures or the aircraft breaking up in flight in my opinion.

First, new satellite imaging does not show a level 5 or 6 thunderstorm event; and even if the A 330-200 had inadvertently flown into the thunderstorms present it should not have failed structurally, with all systems functioning normally. And again it does not seem to account for the attitude and subsequent flight control computer failures.

Second, it is legal (via the minimum equipment list) to dispatch many aircraft without a functioning auto pilot. When Eastern Airlines ordered their initial B-707s they ordered them without auto pilots. Auto pilots click off all the time, they routinely click off in turbulence. On my last flight the auto pilot turned itself off at 35,000, we did not have our hands full and the aircraft did not come apart. What would give the pilots a “hand full” is the cascading failure of the entire fly by wire system.

A stall at altitude in turbulence certainly is a possibility. 3 hours into the flight they were probably at or near their maximum altitude due to gross weight. This charted maximum altitude is lower in turbulence because the wing and flight control effectiveness is reduced in turbulent air. Had AF 447 suddenly encountered the turbulence it certainly could have stalled. However; stall recovery is the most basic requirement of both an aircraft and pilot in the certification process. A simple stall, even an accelerated stall, would not explain why the fly by wire system failures occurred in my opinion. I don’t think it explains why the aircraft came apart in mid air. Air Bus released a bulletin to all operators of the A 330, advising pilots to maintain turbulence penetration airspeeds. This seems premature, and it is the job of the crew to maintain the proper airspeeds. It is the same as telling the pilots, don’t stall. It seems more a subtle message to the press In my opinion.

If the evidence pointed to the crew (as it did in the Colgan 3407 accident), or if there was no evidence at all, then pilot error speculation would at least have some basis. The evidence transmitted by the ACARS points to a fly by wire system failure, followed by in flight break up. Pointing the finger at the crew either subtly or directly without the FDR or CVR is in my opinion irresponsible and unfounded at this time. The evidence shows the fly by wire system was cascading through its failure matrix; why should be the focal point of the investigation.

No Responses to “Air France 447”

  1. Rod Miller 5 June 2009 at 13:20 #

    Here’s my question (pardon my ignorance):

    If I understand correctly, the standby instruments were in some way dependent on computers. Doesn’t this defy the whole point of standby instruments, i.e. that when all the electronics pack it in, you at least have airspeed, altitude and attitude indicator?

    Barring a problem with pitot or static port (like that unlucky 757 in Lima), how could the grew be left with absolutely no instruments at all, which is what, I gather from a number of sources, is being suggested happened on AF447?

  2. Rick 5 June 2009 at 15:53 #

    Two excellent posts & observations in one day! Would daylight conditions have been any better for build-up avoidance? Is the weather radar enough that there is little if any difference? This incident increases my aversion to night flying…as have several incidents in the recent past, including the dumb mistake in Lexington, KY a couple of years ago.

  3. Rick 5 June 2009 at 17:31 #

    Now we’re seeing Airbus issue a directive to replace all A330 pitot tubes, which they think could have iced up and given a faulty airspeed indication. I wonder how they could have jumped to that conclusion and taken such a drastic step as that. Glad they’re doing it, but they must know something, wouldn’t one think?

  4. Chip 6 June 2009 at 06:11 #

    As Rick points out there is a bulletin to replace pitot tubes, because of multiple airspeeds being fed to computers.

    It seems to me they are jumping to conclusions, like the bulletin to pilots to maintain airspeed. That one seems a bit premature to say the least.

  5. Rod 6 June 2009 at 08:22 #

    My question was whether standby instruments in the fly-by-wire system aren’t INDEPENDENT of computers, precisely as a means of keeping an analogue alternative for when the digital system packs up. (Obviously, if all pitot tubes are iced up, no complete info will be available from any source.)

  6. Rick 6 June 2009 at 10:30 #

    I’m reading this morning the AD to replace pitot tubes was issued before this crash, and that this particular airplane had not yet complied with the AD. That sheds a lot of light on this…there was a known defect in the pitot tubes, probably the heating system.

  7. Chip 7 June 2009 at 14:01 #

    See my latest post. The ISIS system is seperate, it deepens the mistery.

Leave a Reply