OT: Airplane crash
- Thread starter RU1977
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I'd take issue with "very reliable plane".
Yes, it's very reliable when viewed from the overall context of the fleet size, passenger miles traveled and service record. But A-3xx series aircraft have a long history of issues with pitot-static systems and FBW software. Airbus has never addressed what I've long felt was a serious problem wherein under certain circumstances the pilot flying the aircraft will provide a control input for nose up or nose down and the FBW system says "yeah, so, um... no..."
Otherwise, there are a couple of curious things about the flight profile of this aircraft in particular.
The descent from FL380 was obviously a controlled descent. It suggests that the flight crew knew the aircraft was in trouble and they were dealing with it. What's a little odd is that they also knew they were flying directly toward mountainous terrain and yet made no attempt to turn the aircraft around. It's also more than a little odd that the descent was a cruise descent - the plane was traveling >400 kts until contact was lost. Generally speaking, if you're trying to work out a problem with an airplane that is intact and under control, you'd slow it down and convert airspeed to altitude.
The sequence suggests that they wanted to get to a lower altitude quickly, but the descent wasn't as fast as you might dial up in a "sudden loss of cabin pressure" situation.
One outside possibility is that they didn't know the aircraft was descending. This seems unlikely based on how the pitot-static system and the autopilot are tied together, but... it's technically possible.
This post was edited on 3/25 8:10 AM by RU4Real
The media LOVES to "interview 'eyewitnesses'" to plane crashes.
The NTSB will tell you that historically the statements of witnesses don't add significant value. No two ever see or hear the same thing and John Q. Public doesn't really know what an "unusual sound" is.
Not only that but eyewitnesses' descriptions of what they see is frequently faulty. In previous situations, eyewitnesses have reported things like fire, explosions, etc. but when the wreckage was recovered, there was no evidence of any of the things that eyewitnesses insist they say actually occurred.
The descent characteristics seems very unusual. If the plane was out of control and going down, it would have most likely accelerated and course varied. It appears from the initial information released that the plan was in a mostly steady (though somewhat steep but not overly steep) descent at a steady speed with a steady course, almost as if it was a controlled flight into terrain.
I'm no expert but one thing I heard that sounded plausible had to do with Ice buildup. Apparently there had been some concerns about cleaning crews allowing water to enter some "flap" underneath the belly of the plane. This water has been known to freeze affecting the planes ability to close the "flap". As a result, the planes computers think it should be descending for a normal landing. Playing into RU4Real's concerns, the pilots don't have the ability to easily override this process. Two organizations have been studying this "issue" and the initial data was sent to them not to long ago. Again, no expert and not sure if this has already been debunked but it seemed possible to me.
This, Whatever happened to the 'eyewitness' that saw MH370 flying low over the Maldives ? He said it was low enough to see the Malaysian Air markings on the fuselage..
How come plane manufacturers don't build this manual override function in? Is it a safety feature to save humans from human error? or just something the companies didn't feel is needed?
Can you provide more info on this? On the surface it doesn't make sense - anything on the underside of the fuselage would have to be an access door of some sort ("flaps" are a very specific thing and are located on the wings) and I don't know of anything like that which would be linked to the actual operation of the aircraft.
I suspect they were talking about the pitot tubes, part of the pitot-static system, which provides the atmospheric pressure inputs to determine altitude, airspeed and angle of attack.
Pitot tubes are prone to icing and have dedicated heater circuits to prevent it. Trouble is, you can't really run them all the time because they use a fair amount of power.
If the pitot tubes ice up then cockpit indications of altitude, airspeed and angle of attack will be erroneous. The autopilot (and the FBW system) will misinterpret these readings and direct the aircraft to respond in an inappropriate manner. Many Airbus planes have been lost in this fashion.
That was a stunning accident. I'm at a loss to understand how two guys can progress to flying heavy aircraft for a major carrier without actually knowing how to land one. Approach stabilization is... well, it's really pretty much the most important thing to know how to do. You do it over and over and over again. You can do it in your sleep. Yeah, sometimes the plane will get out of shape at some point or another, but... these guys had this thing f*cked up for MILES. Just mind boggling.
I am not a pilot, but I'd like to share my modest proposal for required pilot training. After some of the dumb accidents over the last few years, and with the increased automation of the planes, I sometimes wonder whether some of the pilots really know how to fly. (the hero of the Hudson notwithstanding) I realize that sounds crazy, but that San Francisco crash and the Buffalo crash a few years earlier made me scratch my head. I used to sail a lot, and sometimes it was helpful to just get back to basics in a small sunfish or laser. So, my proposal is that all commercial airline pilots, in addition to their time in sophisticated simulators, be required to log a certain amount of hours each year flying a single engine propeller plane - so that we have some assurance that they actually know how to fly. (Of course, there is no indication yet that pilot error was involved in the Germanwings crash).
I've done a lot of both (flying and sailing) and your comment is well-placed. It seems apparent to many people that the increase in automation has led to a certain general atrophy of skill levels when it comes to what we call "basic airmanship".
Back when pilots weren't mostly "B-scale" on the pay grades it was very common to see airline guys with their own planes, flying for the sheer enjoyment of it on their own time. I flew with a lot of those guys. It was a great experience and it was easy to see that they did what they did because they loved it and they were good at it.
Most of the younger pilots I've encountered have a similar sense of romanticism, but not nearly on the same scale. They don't make the same kind of money, their schedules are crazy and they don't have the same opportunity to fly the dream.
Interesting:
"Unconfirmed reports are circulating on professional pilot forums that the Germanwings plane, which crashed in the French Alps yesterday, may have suffered a catastrophic failure of its windshield, incapacitating the pilots."
"Unconfirmed reports are circulating on professional pilot forums that the Germanwings plane, which crashed in the French Alps yesterday, may have suffered a catastrophic failure of its windshield, incapacitating the pilots."
Is this big news? I don't watch news and generally check my local paper and Yahoo News. Did not show up right away on either site, but then again, I am not paying close attention to news today.
I have an in law who used to fly with one of the majors. He had concerns about Airbuses in general for the possibility of them "going HAL" for lack of a better phrase.
Once he "retired" I spoke to him at a family function where he had driven all the way from Maine. I said man you must enjoy driving (since he had recently driven to North Carolina on another trip). I figured it was a control thing but reading between the lines I don't think he had much confidence the new era of pilots on smaller regional aircraft.
Once he "retired" I spoke to him at a family function where he had driven all the way from Maine. I said man you must enjoy driving (since he had recently driven to North Carolina on another trip). I figured it was a control thing but reading between the lines I don't think he had much confidence the new era of pilots on smaller regional aircraft.
"I have an in law who used to fly with one of the majors. He had concerns about Airbuses in general for the possibility of them
"going HAL" for lack of a better phrase."
I recall they had issues in 80s with famous "chainsaw" crash...
This post was edited on 3/25 3:12 PM by RU0517581
Airbus A320 crash
"going HAL" for lack of a better phrase."
I recall they had issues in 80s with famous "chainsaw" crash...
This post was edited on 3/25 3:12 PM by RU0517581
Airbus A320 crash
If that's the same crash I remember from watching a cable show on it, the sophisticated computer system was foiled by the fact that the maintenance crew put a piece of tape over one of the areas the computer uses to draw information (to protect it during cleaning) and forgot to take it off (with the result that the computer was getting faulty inputs and giving crazy/contradictory instructions to the flight crew).
Air France (AF) 447 from Rio to Paris, 2009. I've written about it, here, a few times.
The aircraft encountered convective activity (thunderstorms) at cruise altitude over the Atlantic. It succumbed, initially, to pitot tube icing - which was a known problem on that generation of A-3xx aircraft and was well documented. In fact, the incident aircraft was due to have its pitot tubes replaced as soon as it returned to Paris on the trip in question.
Once presented with erroneous airspeed readings caused by the partial failure of the pitot-static system, the autopilot on the aircraft switched off and the FBW system flipped from "Normal Law" to "Alternate Law 2" - essentially, it swapped the fly-by-wire software and implemented a control routine that changes how the aircraft responds to control inputs.
At the time of the incident the A-330 was being flown by 2 co-pilots. As per policy, the duration of the flight (13 hours) dictated a 3 man crew so that one member could rest at any given time. The captain had briefed the two co-pilots on the weather and status of the aircraft and retired to the crew rest area.
We know that absent very rare and specific circumstances (Pan Am 103, et al), airplane crashes are not the result of a single event, but rather the unfortunate culmination of a sequence of events. In this case the pitot tube icing was the a key element in kickstarting the chain of events, but its tragic conclusion was brought about as a result of a crew failure.
When the autopilot kicked off and the flight crew realized the airspeed indicators (and altitude indicators) were unreliable, the responded by adding power and commanding a nose-up attitude. They did this secure in the knowledge that the A-330 FBW system does not accept control inputs that can result in an airframe stall.
In Normal Law.
What they forgot was that in Alternate Law (1 or 2) that capability is lost. So they stalled the airplane. And rode the stall all the way to the ground - never realizing, at any point, that they were the one causing the rapid, flat descent into the ocean.
Ru4real. thanks so much for sharing your knowledge....I had read about the pilot error on AF 447 but know I get what the problem was.....is it procedure to check the status of the FBW? What you are basically saying is that not only AF 447 pilots screwed up, but they had ample opportunity to address and rectify the problem...
I did not know that a plane of that size can stall so easily....
I did not know that a plane of that size can stall so easily....
There's an indicator on the panel that shows the current FBW rule and there's an audible warning when it changes.
This is the CVR transcript from AF447. You don't have to read the whole thing, you can skip to the last few pages. It shows the horrific level of unknowngness that existed in that cockpit.
All planes stall very easily at 30+ thousand feet. The air is thinner, stall speed increases relative to air pressure. The margin for error is much narrower at high altitudes. That can explain why the aircraft got out of shape, initially. Shit happens, no harm no foul. The ensuing inability to figure it out... that was the real tragedy.
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