Air France crash?
Air France crash?
(OP)
Now that pitot tube icing has been confirmed, were the pilots pulling up to slow their speed?
Why don't pilots carry an aircraft capable GPS with them in the cockpit to see their ground speed? I say aircraft capable because one pilot I knew bought a $120 GPS that had a software load which would not display speeds above 100 mph, just to make you buy the much more expensive $400 aircraft GPS.
Why don't pilots carry an aircraft capable GPS with them in the cockpit to see their ground speed? I say aircraft capable because one pilot I knew bought a $120 GPS that had a software load which would not display speeds above 100 mph, just to make you buy the much more expensive $400 aircraft GPS.





RE: Air France crash?
And, they already should have a GPS system, since we can access similar data from our seats in the passenger compartment on certain airplanes.
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RE: Air France crash?
a different question is why did they pull up when the plane was stalled (or at least the cockpit instruments said it was) ? with a frozen pitot tube mis-reporting the airspeed, i'd've thought you'd've the wings riped off from an overspeed ... plane is flying straight and level at M.8, instruments indicate a stall, stick forward, airspeed (in reality) exceeds Vd ...
and you see all the little unforeseen real world events ... the cockpit warnings cease at sometime 'cause the airspeed is less than some software minimum limit ... that probably confused them too ... "great, we've fixed that stall warning (somehow)", "oh great, no we didn't ..."
RE: Air France crash?
It must be horrible for the families to find out recently that pushing down on the stick likely would have saved everyone.
RE: Air France crash?
The pilots were already confused by conflicting information.
RE: Air France crash?
American Airlines flight 587
http://www.ntsb.gov/Pressrel/2004/041026.htm
Airbus aircraft have had rudder/vertical stabilizer issues in the past. Is the airspeed from the pitot tubes the only input to the rudder travel limiting system? This would make any rudder input during an iceup at highspeed extremely dangerous.
Comprehension is not understanding. Understanding is not wisdom. And it is wisdom that gives us the ability to apply what we know, to our real world situations
RE: Air France crash?
if they had pushed the stick it would have been a race, between thawing the pitot tubes (and reacting quickly to the new condition of the airplane) and ripping the wings off.
we are unfortunately a business of ambulance chasers ... rule changes are predicted by the number of smoking holes in the ground ... no disrespect at all to any involved. I understand that Air France declined to change the pitot tubes, presumably 'cause they had no -ve experience (before now) to drive the change.
RE: Air France crash?
I realize that living in a hellish situation is extremely complicated, especially when your life is ending.
Tough job being a pilot, apologies to pilots reading this thread if my statements seem callous.
Based on news reports, I would bet the families will think pilot error caused the crash. I'd bet my life earnings that lawyers will think that.
RE: Air France crash?
yeah, it'll be a field day for the lawyers. practically speaking, once the pitot system "crashed" they had just about no chance. just maybe they could retain situation awareness (at night over the ocean, in a storm ...) but the plane's computers would be telling them garbage and quite possibly limiting what they could do.
then the lawyers will leap onto why didn't Air France improve the pitot tube (with the Airbus SB, i believe) ? it wasn't serious enough for EASA to make it an AD (mandatory change). great think the lawyers ... bigger pockets to leech off.
i think it was bad luck in a very unforgiving environment.
RE: Air France crash?
I've been to their website before and downloaded all the same reports they had for the Nova reenactment of the investigation.
The media is really bad at this sort of thing.
The Nova show was awful too.
RE: Air France crash?
http://w
The crucial bits from the above link:
-
2:10:05
"
The autopilot then auto-thrust disengaged and the PF said "I have the controls".
Investigators have not confirmed why the autopilot and autothrust disengaged, although this is a normal response of the A330 if its computers detect inconsistency in the airspeed data received from the pitot tubes on the nose.
The airplane began to roll to the right and the PF made a left nose-up input. The stall warning sounded twice in a row.
While the pilot appears to have rolled the aircraft to the left, to counter a roll to the right, he also pulled the aircraft's nose upwards - for reasons yet to be explained."
...
2:10:51
"The trimmable horizontal stabilizer (THS) passed from 3 to 13 degrees nose-up in about 1 minute and remained in the latter position until the end of the flight. Around fifteen seconds later, the speed displayed on the ISIS increased sharply towards 185 kt; it was then consistent with the other recorded speed. The PF continued to make nose-up inputs. The airplane's altitude reached its maximum of about 38,000 ft, its pitch attitude and angle of attack being 16 degrees.
The aircraft automatically trims itself to correspond with the nose-up attitude. In the meantime the standby airspeed indicator's reading suddenly rises, bringing it into line with the reading on the captain's display; the two speeds have been inconsistent for less than a minute.
Despite the stall condition the flying pilot still holds the nose of the aircraft upwards."
-
Don't see any way to read it other than they flew the plane into a stall. Iced pitots likely started the chain of events, but didn't cause the stall.
I recall reading something at the time about AF being unique in that the co-pilot keeps his seat when the captain goes on rest and the relief pilot takes the captain seat (instead of the co-pilot sliding into the captains seat). I can't seem to find the link now, but the story begs the question of who was at the control and how experienced they were.
RE: Air France crash?
It appears that the crew forgot rule #1 and focused on troubleshooting the failed systems. This situation was made worse by the darkness and weather that obscured the horizon and ocean. It appears AF447 simply pancaked onto the ocean at an extremely high rate of descent, wings level, nose high, slow forward airspeed.
An EAL L-1011 crashed in the everglades for fundamentally the same reason: crew was distracted while troubleshooting a balky nose landing gear, late at night over an area area of FL with little or no visual reference [IE: few lights and non-reflective surface]. The entire crew focused on "the problem"... and simply allowed the jet to drift into the ground. http://
There are similar horror stories... such as:
The Air New Zealand crash on Mt Erebus ( http:
or (possibly) the crash that killed Sen stevens in AK last year (http://e
Regards, Wil Taylor
Trust - But Verify!
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For those who believe, no proof is required; for those who cannot believe, no proof is possible.
RE: Air France crash?
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RE: Air France crash?
http://www.youtube.com/watch?v=33NUAy3eomg
RE: Air France crash?
Does the A330 have a pitch indicator? If so between that and rate of descent information you might have hoped they could've done a better job, but still no guarantees by the sounds of it.
Even with artificial horizons etc, disorientation of pilots is still a leading cause of accidents as best I recall it from uni & flying training.
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RE: Air France crash?
I suppose you'd have the altimeter and angle of attack indications that you could still trust.
I figure idle-thrust and a conservative amount of nose down at a reasonable AoA to descend to a safer altitude would have been the solution.
Of course the big problem is figuring out which instruments are lying to you and which you can trust quickly enough to be able to do something with the information.
RE: Air France crash?
An attitude indicator doesn't "need" any pitot inputs. Not sure if Airbus tries anything clever.
Wings level, nose on the horizon and cruse thrust shouldn't get you in too much trouble.
RE: Air France crash?
I was thinking of trying to adopt the optimum glide profile until the pitots cleared but it's probably a lot easier said than done.
From memory the envelope at the speeds & altitudes they fly are on the narrow side.
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RE: Air France crash?
IMHO the whole aircraft is "clever".
Maybe TOO "clever" ?
I bet there was a cascade of annunciators and shed systems that these poor guys were just overloaded.
RE: Air France crash?
B757 took-off at night [in WX, low/poor visibility] and encountered erratic pressure instrument readings. The crew was unable to control the airspeed and altitude readings were totally unreliable... and the aircraft ended-up in the ocean.
When the wreckage and FDR/CVR were discovered [Wikipedia]... "investigation into the accident revealed that masking tape was accidentally left over some or all of the static ports (on the bottom side of the fuselage) after cleaning the aircraft that eventually led to the crash."
htt
Disorientation and/or distraction [such as messing with the radio or NAV system or texting while driving], can be fatal rapidly.
Regards, Wil Taylor
Trust - But Verify!
We believe to be true what we prefer to be true.
For those who believe, no proof is required; for those who cannot believe, no proof is possible.
RE: Air France crash?
but when your attitude indicator is telling you garbage, and you're trained to believe the instrument over your personal "attitude indicator", and you're flying at night over the ocean in a storm ...
what chance do you have to level the wings or point the nose at the horizon ? "old" planes had "stick free" stability ... do fly-by-wire ? and how does a flight control computer behave when it's getting zero input ? or inputs that are highly different (if it senses both pitots, and only one froze) ?
there was an accident out of Cuba, a B757 i think, where the pilot's pitot was malfunctioning ('cause a spider had made a nest in it ... you can't dream this stuff up !). i thought one of the conclusions of the investigation was the flight control computer should sense both pitots ... i think it was sensing only one. similarly why record only one ??
RE: Air France crash?
In this case it was the EPR probes that iced up, making the pilots believe they were at takeoff power settings.
RE: Air France crash?
But then it also seems odd to me that applying power would be used to recover from a stall at those flying conditions.
I've always thought following this rule was a major factor in how Captain Sullenberger was able to successfully ditch 1549 in the Hudson.
RE: Air France crash?
I know that GPS can be used for attitude sensing (<1 degree accuracy in pitch roll and yaw), maybe one should be added to aircraft as a simple backup system. GPS can be jammed electrically, so that is a hazard.
RE: Air France crash?
But I haven't seen anything that suggests that the attitude indicator was malfunctioning. To the best of my knowledge an attitude indicator does not have any connection to the pitot system, so it would be unaffected by pitot icing. But if I'm wrong here please correct me.
They seemed to be able to keep the wings level. With no visible references it's likely that they were using the attitude indicator for that. Or does the Airbus also have an old-fashioned turn and bank indicator too?
So why did they believe the attitude indicator for roll, but not for pitch?
RE: Air France crash?
Regards, Wil Taylor
Trust - But Verify!
We believe to be true what we prefer to be true.
For those who believe, no proof is required; for those who cannot believe, no proof is possible.
RE: Air France crash?
RE: Air France crash?
h
One thing that came out in the papers is that commercial/civil pilots are not trained to fly by AOA (military pilots are), nor are commercial aircraft IIRC equipped w/ AOA instrumentation. In aero class at least, it's all about alpha which tells you so much. Dunno how it's justified not to give pilots something so useful.
RE: Air France crash?
http://www
The link is for page 22, which is around the release date of the BEA report so the discussion is more about the known data rather than wild speculation from the past three years.
RE: Air France crash?
Interesting that reacting to a stall has changed from priority of Increased Power to new priority of Nose Down. Although if you don't know your altitude, that can be scary (carry two personal GPS's, at least you'll have your altitude handy).
thanks for the links.
RE: Air France crash?
(from the NTSB report)
"Unfortunately, instead of following the established stall recovery procedure of adding full power and lowering the nose to prevent the stall, the captain only added about 75% power and continued applying nose-up inputs. As the aircraft came even closer to stalling the stick pusher activated. The stick pusher is designed as a last ditch effort to lower the airplane's attitude to fly out of the stall. The captain overrode the pusher and continued pulling on the control yoke resulting in the upset and subsequent loss of control"
Which at first glance by a rank amateur, seems like is what was happening on the Air France accident.
RE: Air France crash?
RE: Air France crash?
Transport category aircraft do have a third attitude indicator to allow the flight crew to choose "best two out of three" on the theory that two of the three won't die at the same time.
Attitude indicating systems are not connected to the air data systems in any manner that should allow the air data system outputs to influence the attitude displays. Generally the attitude indicators link directly to the inertial platforms and any air data information in the attitude indicator system is normally only data passed to the indicator for display and cannot modify the basic attitude indication.
That being said, the Airbus series of aircraft do not have control cables where as a last resort the flight crew can ignore all system inputs and place the flight controls exactly where their trained instinct tells them to set the controls. What I mean byt that is while I am NOT a software expert, i believe in any fly by wire system somewhere, somehow an electronic circuit passes judgment on the pilot input and decides whether to allow, modify or deny that control movement.
So one possible scenario could be: probes ice over and air data inputs begin to change, causing flght control software to make decisions on what to believe and what not to believe, causing flight controls systems to accept/modify/deny pilot inputs based on the software laws.
Note that I am not speaking of the autopilot and autothrottle systems as those systems disengaged, presumably as intended by design when the inputs became unbelievable. I am speaking of the electronic systems that interpret the signals from the side yoke, rudder pedals and throttles to develop and send signals to the flight control actuators.
Note that I am neither involved in the investigation nor am I a trained investigator. Consequently feel free to take my input with a grain of salt, and you would not be out of line to tell me I am full of it if your knowledge of Airbus systems is greater than mine (which would not take much).
The biggest flaw in my scenario from the available data is that the recorded data shows the pilot flying deliberately applied nose up input, and there was no indication that what the pilot was commanding was refused or modified by the fly-by-wire system. I only present my scenario to note that (in my opinion) we have taken the flight crew too far out of the control loop and if I were a pilot I would feel much better if there were mechanical cables between my controls and the flight control surfaces. And I think that mindset is reflected in flight crews that don't seem to go back to basic stick and rudder with complex failures.
I would think that basic stick and rudder skills would dictate the Attitude + Power = Performance could have helped, but I don't know that flight crews today pay that much attention to it with all the eletronic systems doing the monitoring. Flight crews from olden days could normally recite "at this weight at this altitude I use this throttle setting and this attitude." In these new electronic aircraft I don't know if the flight crews do that nowadays.
Also keep in mind that I have hundreds of hours on the flight deck observing and interacting with flight crews, but that has not occurred for at least 15 years. Thus I have NO flight deck time on a fly by wire aircraft from which to draw conclusions. Just one more reason to write off my comments if they don't apply to today's flight deck environment. I confess I am rapidly reaching dinosaur status in aviation.
RE: Air France crash?
Only when you're not stalled, which is what they were. Not that they were applying full power, though. They were falling at 10,000 ft/min for a solid 3 minutes because they were stalled out.
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RE: Air France crash?
Watch the Mayday/Air Crash Investigation episode on AeroPeru 603: http://youtu.be/pXTbseOEFdQ
RE: Air France crash?
The B-52 crews I used to work with had a saying, "When you have multiple emergency warnings, break out the flight lunches". In other words, don't start making changes without thinking things through to confirm a genuine emergency.
But your point is very well taken that once they were in the stall, the equation Atitude + Power = Performance no longer had any validity at all.
RE: Air France crash?
I would see the major difference here as the AF crew had several hours of an airworthy, operational aircraft before the confusing warnings, and thus I would have expected the most experienced crew member at the moment (in this case the Pilot Not Flying as the Captain was off the flight deck) would have said, "Don't change anything until we sort this out". Obviously since the autopilot and autothrottle disengaged, the admonition "Don't change anything" should be interpreted to mean "grab the controls but maintain attitude, throttle position and wings level until we can verify a problem." The AeroPeru crew effectively NEVER had reliable information after liftoff.
But of course I am not sitting in a thunderstorm at night with a flight deck full of jangling alarms and the responsibility for several hundred people riding on my shoulders, so what may sound reasonable now was obviously hidden for the real players during their emergency. Otherwise they would be going about their daily lives today and remembering their close call.
RE: Air France crash?
I disagree.
I wouldn't think the airspeed indication would respond in ANY normal fashion with the static ports sealed. I really don't see how how they would have known where V1 was on the roll (or any of the other takeoff critical "V speeds" published in the POH) in this condition.
RE: Air France crash?
RE: Air France crash?
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RE: Air France crash?
if the static ports are stuck at SL, your computer is going to have trouble understanding a -ve dynamic pressure.
RE: Air France crash?
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RE: Air France crash?
example, if I hook up my Barfield pitot/static tester to an aircraft's airdats system (and for the sake of this example, lets not have an air data computer in the mix), and I apply NEGATIVE pressure ie, below field elevation, to the STATIC port, the apparent airspeed of the indicator will increase.
Conversely, if (after returning the system to field elevation) I close off the static port reference, and attempt to add pitot pressure, it would require a much higher pitot pressure to achieve n airspeed (on the indicator), then if the static port is open to ambient pressure.
RE: Air France crash?
After shaking my head on what's coming out of the CVRs and the black boxes, I'll go out on a limb and make a prediction on how the flight management computers will be upgraded to help prevent future occurrences.
1) enable the flight control system to record GPS and INS vertical/horizontal data;
2) by comparison of GPS and INS speed data to the aircraft's ADC, the FMS can calculate *and store* the corresponding winds aloft components;
3) should a failure occur in the ADC, the FMS could then step down to output speeds provided by both GPS and INS, adjusted by the stored wind data in order to display semi-accurate computed horizontal/vertical airspeeds. I believe the computed airspeeds would accurate enough to fly the plane safely.
Obviously the accuracy of the stored winds aloft data would degrade as the aircraft moved to a different geographic zone, but that occurs over many minutes during which the crew would be able to sort themselves out to prevent the type of situation that befell AF447.
Does anyone know if this has already been tried out?
RE: Air France crash?
maybe they should get a bigger dog ... the joke being the plane's computers fly the plane quite well enough, and they put a dog on the flight deck to prevent the pilot's from touching anything.
RE: Air France crash?
Dik
RE: Air France crash?
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Air France crash?
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RE: Air France crash?
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RE: Air France crash?
Ref. Coffin Corner
http://
RE: Air France crash?
RE: Air France crash?
I think there is a distinct correlation between pressure and speed. Several could be combined to determine overall flying condition.
They are also light weight and relatively inexpensive for the ones I've seen literature on.
Dik
RE: Air France crash?
There's a distinct correlation between pressure DROP and speed. That's the whole point of a Pitot tube.
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RE: Air France crash?
dynamic pressure = 1/2*rho*V^2
IKYK
RE: Air France crash?
I highly recommend reading this article becasue if he truly is an A330 pilot, his perspective is far more valuable than mine.
http://
RE: Air France crash?
Dik
RE: Air France crash?
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RE: Air France crash?
Ok what am I missing here? I thought a pitot tube measured dynamic pressure. I thought a static port measured static pressure.
The fact that the two are frequently incorporated into one sensor head, I though was co incidental.
B.E.
The good engineer does not need to memorize every formula; he just needs to know where he can find them when he needs them. Old professor
RE: Air France crash?
"tests confirm GPS jamming by LightSquared" ...
"Initial testing of GPS receivers confirms aircraft navigation systems will experience significant jamming from thousands of broadband-wireless transmitters planned to be deployed across the U.S."
RE: Air France crash?
Are you talking about this?
The AOPA is already popping and spitting about it.
B.E.
LIGHT ADVISORY LightSquare Testing May 16, 2011 – May 27, 2011 Boulder City, NV
Notice Number: NOTC2978
FLIGHT ADVISORY
LightSquared Testing at BVU
May 16, 2011 – May 27, 2011 Boulder City, NV
LightSquare (mobile broadband service) testing is scheduled as follows and may result in unreliable or unavailable GPS signal.
More information can be downloaded from the link below.
https:
The good engineer does not need to memorize every formula; he just needs to know where he can find them when he needs them. Old professor
RE: Air France crash?
It doesen't make any sense to me.
I believe there is more to it, no telling what though.
RE: Air France crash?
Nose Up, still falling like a rock; Oh, maybe I fubar'd and stalled out the plane.
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RE: Air France crash?
FWIW, i think they "deep stalled" the plane ... and odd thing to do with a low tailplane.
RE: Air France crash?
This is pure speculation, but I would think that full throttle on a set of pod mounted engines would tend to push the nose up.
With the pilots also applying up elevator, it would produce a result like an old man trying to climb over a gate.
B.E.
The good engineer does not need to memorize every formula; he just needs to know where he can find them when he needs them. Old professor
RE: Air France crash?
http:/
RE: Air France crash?
You still need to poke a tube out into the airstream, and oriented along the forward flight direction (x axis), in order to measure the total (stagnation) pressure. It's the tube that potentially ices up, blocking the transmission of that pressure to the sensor face.
RE: Air France crash?
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RE: Air France crash?
That would be a better stall indicator. The wing always stalls at given AOA. Airspeed and pitch for a given airspeed vary with weight.
Indicated airspeed is used as an indicator of AOA when aircraft weight doesen't vary much.
Granted critical speeds should all be calculated for the weight
before takeoff.
I believe the AC computers recovered from the AOA issues and the crew inputs kept it in stall for a very very long time.
I wonder what kept a wing from dropping allowing the aircraft to enter a spin.
I've gone up in a Decathlon for spin practice. We practiced a manuver called rudder stalls. You basically stall the airplane but apply opposite rudder every time a wing starts to drop.
The aircraft wing remains in a stall, the aircraft porpoises its way through the sky, +/- less than 100 ft, all the while loosing altitude because the wing has no lift.
RE: Air France crash?
Yaw damper?