United Airlines jet landed after losing primary flight instruments

Besides the excellent rebuttals from others here, let me add that no Airbus crashed at the 1988 Paris Air Show for four good reasons:

1) No Airbus ever crashed at a Paris Air Show.
2) There was no Paris Air Show in 1988 (the show is held on odd-numbered years).
3) Air Show demos are not flown with passengers (Come one guys, try to think straight from time to time).
4) The accident happened at the airfield of Mulhouse-Habsheim in Alsace/France , at a minor club event. The Paris Air Show would never have approved such a dangerous maneuver from the pilot.

I suspect this common error about the "Paris Air Show" started when "someone" wrote that phony report: "I have a pilot friend... if it ain't Boeing, I ain't flying". (One pretty dumb thing to say)

1) The crew had licences and qualifications to undertake the flight but did not have the technical skills, the experience, and the methods of a test crew to use this flight programme, even if it was not a test flight.
2) The Airbus Customer Acceptance Manual specifies performing the low speed check in landing configuration at FL 140.
3) The crew decided, without preparation, and in particular without a call-out of the theoretical minimum speeds indicated in the OFC, to undertake the check of the low speed protections at an altitude of about 4,000 ft.

 

Some here have their minds made up and even the naked truth will not sway them. I was wondering where this was going until a Real Pilot stepped up and blessed us with the truth.

Good Post.

 

Wily, those are all accurate points, but unfortunately none of that is revelant. The crew did a lot of things wrong. I won't comment on their skills and absolutey they should have done the manuever at the correct altitude. Had they done that they would probably be alive today and we wouldn't be talking about this. The crew would have had a beer that night and written up the airplane for a problem with the AOA system and none of this would have come to light.

That is not the issue here. Please correct me if I am wrong, but the low speed check is designed to excecise, at a safe altitude, systems that are supposed protect the aircraft at low altitude and low airspeed situations. Those systems didn't work as designed. For whatever reason the aircraft approached a stall. The stall warning went off and the pilot initated a recovery using the recommended stall recovery procedure.

The aircraft didn't recover primarily because the automatic trim was disabled. Where it happened and to what crew it happened to isn't relevant. What is revelant is what actually happened and that the software that was designed to help fly the plane added workload just when the pilot didn't need it. It just as easily could have happened to a crew that had to do a last minute go around halfway down a wet runway just before they were going to flare, or for any one of a thousand other reasons. The low speed protection system is in the airplane because things like that happen, not to perform a test procedure.

There is no dispute that the aircraft approached stall and the pilot initiated a recovery, and subsequently entered a second stall that was unrecoverable. The second stall was directly the result of the elevator trim being set in the full nose up position. The disabled trim was a direct result of the speed sensors not being in agreement so the aircraft didn't know how fast it was going. Since it didn't know what to do, it stopped doing anything.

It is also important to note that even though, as the airspeed recovered (and presumably, came into agreement since the reason they disagreed went away), that the computer didn't recognize that fact and recover and take the control system back to normal law. Robust software will do that, most software today doesn't. Once you go to degraded mode you are stuck there until you tell the airplane it's OK to go back and if you are in a high workload situation that isn't going to happen.

So to recover they would have had to trim the nose down just as they were adding power and pushing the nose down. Since in normal situations the trim system would do that automatically, they would have had to look at the display warning and start trimming just as they were trying to push the nose down and push the throttles forward all while the stall horn was blairing. They didn't recognize that the trim was inop so they didin't retrim, and the rest is history.

We could all say "I'm so smart and such a good pilot that it can't happen to me, look at all the things those guys did that weren't to procedure". And they did a bunch of things wrong. But the real point is that these guys got the airplane into a near stall, they applied power pushed nose down, and the aircraft, instead of recovering, pitched up, stalled a second time and went right in.

What you have to ask yourself is, if that sequence of events had happened to you, assuming that you had a lot of time in the airplane, and had gotten very used to letting the airplane trim itself all the time, would you have caught the failed trim and done it right? I'm not sure anybody with a lot of time in the airplane would have been looking for the trim buttion in a stall since the airplane does that by itself essentially all the time.

We are all taught that we add stick force and then trim to reduce the force as the airspeed changes. When we learn stalls, we trim the aircraft back, pull up the nose, bleed off airspeed and execute the stall. When the stall breaks, we are taught to push down the nose, add full power, and then, as the airspeed increases and the stick force comes up, to retrim. Trimming in the stall isn't required because the airspeed hasn't come back up yet, and the stick forces are still low, so you could argue that having to trim as part of a stall recovery is not part of basic stall recovery training.

Just last year, Boeing and Airbus agreed on a recommended stall recovery procedure for aircraft with under wing mounted engines. This was done in response the Colgan Air crash and the crash of a DC-8 and recognizes the effects of the addition of takeoff power on the pitch attitude of the airplane during recovery. This new stall recovery procedure is centered on the application of nose down control inputs and avoids the application of takeoff power until the nose has pitched down and the airspeed has started to recover. It also recommends that if the pitch attitude does not come down, power should be REDUCED. The use of power in this case is exactly the opposite of the previous procedure. What is interesting to me is that this new procedure might have prevented the second stall that occurred in this case because if the elevator trim is stuck in the full up position, pulling back power will help the nose pitch down. The crew in this case followed the recommended stall recovery procedure that was in use at the time and that just caused a second stall event because of the trim being set to full nose up. You think maybe Airbus recommended this procedure because they can envision situations where their airplane can get close to a stall and the trim is disabled in the full nose up position?

 

Actually it is understandable... The recording starts with:

"497 we need to vector back to the airport. We have a smoke issue with the airplane." Then he asks for the longest runway and declares an emergency... So it makes sense for the paper to assume there was smoke and not just an alarm. Remember the early reports were based almost exclusivly on the recording from liveatc.com

 

So the airplane reported smoke that wasn't there, probably due to some faulty sensor? As far as I'm concerned, that would be another strike against Airbus.

 

I dont know which tire blew out but if they had massive electrical problems they probably lost anti-skid which usually results in multiple blowouts in emergency stop situations.

 

The NTSB released this information today about the incident.

http://www.flightglobal.com/articles/2011/04/08/355383/ntsb-no-signs-of-smoke-in-united-a320-emergency.html

 

"The CVR is of good quality and captured approximately 7 minutes and 30 seconds of the incident flight. The FDR contained in excess of 25 hours of data and captured approximately 18 minutes of data relevant to the incident flight. Both the CVR and FDR stopped recording data prior to landing."

http://www3.ntsb.gov/Pressrel/2011/110407.html

 

Here is a link to a UK investigation of what they describe as a serious incident on an A319 on Sept 15, 2006. The system failures that occurred on this fight are very similar to the problems that occurred on the flight that is the subject of this thread so it would appear that loss of a lot of electical systems can and has happened to Airbus aircraft.

http://www.aaib.gov.uk/cms_resources.cfm?file=/4-2009_G-EZAC.pdf

As you can see in this report, although no loss of life or damage to the aircraft occurred, it was a serious enough incident that it was investigated by the Air Accidents Investigation Branch (similar to our NTSB).

On this particular flight the crew was using the APU because one of the main generators had faulted (as allowed in the aircraft procedures and following the MEL for the aircraft). A second system faulted and then all hell broke loose when most of the electrical systems in the aircraft shut down.

The good reading is in the end where they list the systems that were lost following this malfunction of the bus system. Over 100 systems failed on this flight, including systems such as the passenger oxygen masks (both auto and manual deployment) the pilots display (copilot still had his) and lots of others.

What is interesting here is that there were only two failures, that were totally unrelated that caused this cascade of events. That is not supposed to happen. Two isolated single point failures aren't supposed to bring down the whole system. Just like this United flight where the pilots lost all displays and were flying the aircraft on the RAT (Which indicates that in this case the failures were more extensive than the UK incident).

Since we know little at this point why the United flight got to the point where most of the electrics shut down, I'm not going to speculate on the how it happened. I'm just saying that massive electrical system shutdowns have occurred in the past on Airbus aircraft. That is a fact and it is documented in the link above. Considering how reliant these aircraft are on their electrical systems you would think that they would be more robust, but they apparently are not.

Note too, that pilot error was not an issue here, the pilots did nothing wrong (other than to spend too much time trying to call ATC on dead radios... Oh yea, I forgot to mention that ALL the coms went dead and the transponder was off line for a while and while it was down they came within 19 seconds of a mid-air at 32k ft)....

The Air Accidents Investigation Branch classified this incident as Serious, and I don't think the United incident is any less serious.

 

Your are right, you should never fly an Airbus. They simply fall from the sky and Boeings do not. Come on. Lets look at system failures on all aircraft, they all have them. Let's talk about 737 yaw dampers. That didn't just cause an emergency landing, no in two seperate incidents it killed everyone on board. Additionally, there seems to be an problem with metal fatigue in Boeings and a pesky center fuel tank problem on 747s.

You insistance that the pilot at the air show in France was commanding the aircraft and it was not following his imputs is simply inaccurate. He did nothing and thought the airplane would respond the way it would at altitute, it did not, and when he finally took over it was too late. You fear that the airplane will not allow a pilot to fly it if there were an electrical failure is misplaced. In the United incident they were in an emergency electrical situation, the A320 is fly by wire, and there was no loss of flight control. The systems operated as it should when systems fail as they do in every aircraft. But go ahead and fear the airplane. But you must realize that if every airplane had the protections the Airbus has there would be fewer accidents... And I will repeat the Buffalo crash would never have happened.

 

In that incident, it cannot be proven or disproven what actually happened. According to several investigations the data from the flight recorders has been tampered with. We will never know concluisvely what happened.

Here is a 58 page analysis of all of the issues with the flight data records of that flight. Specifically there are issues with when power was applied and when the engines actually provided additional thrust. There are also discrepencies that have to do with how fast the aircraft decelerated from 140 kts, and in particular the CVR appears (page 48) to have been modified to shorten the distance between power application and the impact with the trees. In short your statement that the pilot did nothing cannot be proven or disproven, and my contention that the engines didn't accelerate cannot be proven or disproven. Any evidence that could prove that is gone.

http://www.crashdehabsheim.net/CRenglish%20phot.pdf

One thing that cannot be disputed is that the pilot never had access to the recorders. If they were tampered with it was by people who had a vested interest in making sure the aircraft wasn't blamed for the crash, and the pilot was.

 

That's because it didn't happen, you're lying again. They were not 'unrelated." The primary generator failed. Then the second generator failed. Trust me, they are related... The -causes- of the failures were unrelated but (Duh you nitwit) if they were related you'd be howling about a single point to fail... That's why they have redundant isolated systems.

Again, you're lying. The two failures did not "bring down the whole system." Some systems failed due to lack of power. (even some important ones!) The pilots felt it was safe to continue to the original destination rather than divert. The pilot's instruments failed but the FO's worked... There was no "bringing down the whole system" the redundant systems worked!

You nitwit, they have happened on every aircraft! I lost all power in a 172 back in the day... but somehow I managed to set it down in one piece. (although there was a Tomahawk that scared me when it took off from a runway I thought was clear)

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Your whole point is shot down by the very report you link.

Let's review what happened...
First, the primary generator failed. Then the second one failed concurrently.... STILL the redundant systems were robust enough the pilots decided they did not have to divert and they could continue on to their destination. The FO did a regular ILS landing.

In case the point is not clear... the redundant systems you keep saying don't exist, not only exist, they worked.

 

Sigh:

http://www.fss.aero/accident-reports/look.php?report_key=1388

http://www.fss.aero/accident-reports/look.php?report_key=1169

http://www.fss.aero/accident-reports/dvdfiles/US/1969-01-18-US.pdf

http://www.fss.aero/accident-reports/dvdfiles/US/1996-06-19-US.pdf

http://www.fss.aero/accident-reports/dvdfiles/US/2003-03-26-US.pdf

http://www.telegraph.co.uk/travel/739310/Boeing-777s-history-of-power-failure.html

http://www.dailytech.com/Boeing+787+Test+Aircraft+Makes+Emergency+Landing+after+Electrical+Fire/article20123.htm



I'm sorry solofast, I interrupted you... you were saying...

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Excuse me but that is the most idiotic and nonsensical statement that I have ever seen.

First I am not lying, please explain what statments of fact I have made in this case that are not absolutey factual.

Second you seem to be talking in circles. You say the failures are not "unrelated", but that the primary generator failed and then the secondary generator failed from different causes. You said trust me they are related. Please explain how they are related.

After the first generator failed the second is supposed to pick up the load. It did not. The reason it did not is not in any way related to the first failure other than the fact it was activated. This is the classical definition of two unrelated failures.

Let's go back to the beginning. One generator failed. That is a fact. When the second generator was demanded it also failed. That is a fact. The second generator failed for a different reason than the first. That is a fact. What you had was two generator failures for different reasons. The real problem came when the aircraft tried to compensate for the two different failures. Airbus admitted this and has made a modification to the aircraft to try to prevent this failure mode from reoccurring.

In the report Airbus agreed that they had a deficiency and have addressed it with the following modifications:

Finally, while the flight was successfully completed, the failures were significant enough for the board to investigate and Airbus to modify its systems. Your attempt to whitewash over the incident not withstanding, if the UK Air Accidents Investigation Branch thought it was a serious failure and Airbus modified the aircraft to attempt to preclude it from happening again, who are you to suggest that it wasn't.

My point in bringing this incident up was that the problem was failure of the bus control system to isolate and properly compensate for the generator failures that occurred. The report makes it clear that the system did not operate as designed, and Airbus has modified the system to attempt to address those faults.

You have brought up a littany of incidents where power was lost on different Boeing aircraft. Power losses have and will always occur. That's not the point. The point is, when they occur, do the systems operate as designed, or is the aircraft doing something that it isn't supposed to do? In this case the Investigation Branch and Airbus found that in this case they did not operate as designed. In the incidents you have mentioned, did each of the systems operate as designed? If they didn't then they have a problem too. I'm not suggesting that other aircraft don't have problems, but you can't suggest that just because other aircraft have problems that it is ok for Airbus to have a problem.

 

Dude, it's over. You was pwned in the post above your last one.

Now you're just making yourself look sad. And as you like to say.... That is a fact.

 

Are you aware that the pilot survived the crash? He provided quite a bit of evidence that he expected the aircraft to go into stall recovery and when the airplane did not, he tried to do it himself.

 

Yes he stedfastly maintains that he pushed the throttles full forward, which can be verified by the recording on the CVR. The question is when did that happen? Did it happen, as he maintiains in time to climb or did it happen when the CVR says it happened, a few seconds before impact? Since the CVR and the FDR don't sync, we will never know for sure and that is unfortuante.