News French plane lost over Atlantic

[Liberator]

Have any of you realized debris was found. It is a 3 mile long way of debris in the Atlantic.

 

[garyw]

Have any of you realized debris was found. It is a 3 mile long way of debris in the Atlantic.

Yes. Not yet confirmed that it's from the A330 though.

 

[Urwumpe]

Yes. Not yet confirmed that it's from the A330 though.

It is confirmed it is from the A330. An empty passenger seat was found.

What is not known yet, is how much of the aircraft the floating debris represents. Was this debris field all that there is, or are there more small debris fields? 5 km is a very tiny field after such a long time, if it is all of the plane, this means a very very steep impact angle.

 

[Linguofreak]

I've heard that there are 2 fields separated by 37 miles, pointing to a mid-air disintegration.

 

[Andy44]

Question: I have seen very light planes with water-activated emergency transmitters. One I saw had a sort of wax seal around it that disolved in seawater and allowed the device to float to the surface. Do jetliners have anything like this?

 

[Moonwalker]

Question: I have seen very light planes with water-activated emergency transmitters. One I saw had a sort of wax seal around it that disolved in seawater and allowed the device to float to the surface. Do jetliners have anything like this?

Boeing and Airbus aircraft are mostly equipped with ELTs (Emergency Locator Transmitter) by Honeywell (model RESCU 406, transmitting on 121.5, 243 and 406MHz). It weighs about 3kg and does not float as fas as I know.

ELT location on the A330:

 

[SiberianTiger]

I've heard that there are 2 fields separated by 37 miles, pointing to a mid-air disintegration.

This is raising the odds of the plane being blown up a notch.

 

[Graham2001]

This is raising the odds of the plane being blown up a notch.

Not necessarily, turbulence induced disintegration could have produced the same effect, but I can think of at least two incidences of strong wind gusts ripping aircraft apart.

One of those involved a plane trying to penetrate a thunderstorm between two cumulonimbus clouds, the wind gusts ripped off the elevators on the tail, the unbalanced stresses then ruptured the fuel tanks causing an explosion. (See: Wikipedia: Braniff Flight 250)

The other is the BOAC 707 crash near Mt Fuji, where the winds again ripped the tail off the aircraft causing disintegration at altitude. (See: Wikipedia: BOAC Flight 911)

 

[SiberianTiger]

If this is the case, it creates a bunch of problems for the EADS. Airplanes don't disintegrate because of flight stresses each other day.

 

[Linguofreak]

This is raising the odds of the plane being blown up a notch.

The problem with that is that the plane did transmit telemetry indicating a problem for four minutes before the loss of cabin pressure was recorded. A bomb would most likely have caused an immediate loss of cabin pressure, as it would go off in the fuselage somewhere. My theory remains storm related damage -> Loss of control -> Overspeed or other overstress -> Disintegration in mid air.

 

[Urwumpe]

If this is the case, it creates a bunch of problems for the EADS. Airplanes don't disintegrate because of flight stresses each other day.

No, it doesn't. The design specifications are not for keeping the plane intact in all possible circumstances. The planes are all world-wide designed for a known range of turbulences, and have to be tested for that. Particularly strong turbulences, especially if they are rare, are not part of the design specs. In this case, in the ITC, you can have turbulences, which are far stronger than the turbulences you are designed for. The normal turbulence there is already in the top range of the statistics, and you can have rare turbulences, which lay outside your range of known turbulences. But like always in statistics - if you would now set the maximum to the possible turbulence that possibly caused the crash, you have to expect still another even rarer turbulence, which is much stronger than this one.

The Airbus crash in Brooklyn is a fine example: The plane lost the stabilizer, because the pilot used the rudder from one extreme to the other, causing a destructive oscillation. This case is now not normal - there was a lot of piloting error involved, as the pilot unintentionally amplified the initial turbulence instead of dampening it.

Was the plane designed the wrong way? No. The opposite would be like equipping all planes with much stronger landing gear for compensating for bad landings. Or force them to have much much much more thrust, to have more freedom in the take-off phase.

 

[SiberianTiger]

The alternative is simple: it is either a human error which driven the airplane beyond a safety range allowed for by the specifications, or there was no human error, and in this case the assumptions made by the designers were an underestimation of the possible harshness of conditions.

The latter case is not favourable for the EADS.

 

[Graham2001]

If this is the case, it creates a bunch of problems for the EADS. Airplanes don't disintegrate because of flight stresses each other day.

It just depends on how they are flown, the Brooklyn Airbus crash is a classic example of how pilots can break aircraft.

An earlier example, and one which did involve a plane in bad weather scattered debris over a 20km area. (See: Pilotfriends: Northwest 705).

This is the one that lead to the now standard procedures for flying through storms

 

[Liberator]

An explosion would've resulted in immediate damage, but a small bomb could've caused parts of it to degrade along with the wind and electricity would've caused it to disintegrate. Also, a fuel leak could've caused it because if it hits electricity it could've caused a fire destroying the structure causing a loss of cabin pressure. (Right now, I'm studying all the ways the plane could've crashed. Along with the causes and effects.)

 

[Urwumpe]

The latter case is not favourable for the EADS.

Not EADS - the people who define how much stress an aircraft has to endure, are the important national transportation boards. Especially the US FAA.

If they would discover, that EADS build the A330 not according to the testing standards, it would be a EADS failure. If EADS followed the standards exactly (and the A330 is not one of the safest planes out of nowhere), the result would be that the turbulence standards for new aircraft designs need to be raised - or air traffic control has to stop flights through a region with such weather conditions (strong thunderstorm cluster). And this would mean: Brazil might be impossible to be reached in the European Summer on most days of the month.

Just taking one extreme and absurd example: Imagine the standard would be introduced that planes have to survive the explosion of 1 kg high-velocity explosives in the freight compartments. This would be possible to mitigate - you would need stronger structures and a new, less optimal shape for the cargo compartment to vent shockwaves. But the result would be much more expensive planes, more expensive plane tickets and less cargo per passenger. And could be broken by attackers using 2 kg or place multiple small bombs in the cargo.

 

[Moonwalker]

Well, the A330 is a beautiful wide body aircraft which has been well designed and certified. It is, beside the A340 (no personal injuries within 16 years of operation), one of the safest civil jet aircraft. Within about 15 years of operation there have been two accidents until last monday while one (for now) was caused by the aircraft (a fuel leak), which resulted in the longest glide of such an aircraft type ever followed by a safe emergency landing rescuing all 293 passengers. The aircraft still flies (no, it was indeed not the famous Gimli Glider). The first accident was caused by pilot error.

The latest and so third accident likely was caused by heavy storm which is part of human error and not related to bad limitations. Those heavy passenger aircraft by far are not designed to fly through storms safely, especially not through intertropical storms. I don't think it is adequate to discuss such limits. Flying through storms is never part of what such airplanes are designed for. Storms have to be avoided generally, as far as possible.

I guess the cause of the latest accident was indeed heavy lightning strikes, leading to multiple systems failures and uncontrollability of the aircraft, resulting in a fatal crash. The Pilot had more than 10.000 flying hours, and more than 1.000 hours on the A330.

 

[Dickie]

There is always the human factor when discussing the flight safety 'chain', the following struck me as a possibility after reading this thread over lunch:

Pilots are in the cockpit, flying into bad weather which for one reason or another, they have decided to fly through. They're IMC, at night, and presumably with frequent lightning flashes around them - the net result of which is zero visual references as to the attitude of the aircraft, the aircraft is also experiencing severe turbulence, which in turn reduces the pilot's ability to 'feel' what the aircraft is doing. Perhaps a single lightning strike hits the aircraft, not enough to cause catastrophic failure of the airframe but enough to cause the computers* to require a restart or whatever - this of course means the glass cockpit instruments in front of them are gone, which then means they are flying 'seat of the pants', only they can't without visual references or the feel of the aircraft.

It is worth pointing out now that it is not uncommon for pilots in these conditions to develop such things as 'the leans'; a condition where for whatever reason, when devoid of visual references the pilots intuition decided that 'up' is not where is should be thus causing severe disorientation (anyone who has flown in a manouvring aircraft in complete IMC will be know how disorienting it can be.)

So, what if when waiting for his glass cockpit to return, one of the pilots 'knows' that the aircraft is at the wrong attitude, and in his attempt to correct it, somehow either overstresses the airframe or flies his aircraft into the deck?

As far as a theory goes, it's just that, but as far as I can tell it does offer an explanation. Any thoughts?


*Whilst having some knowledge and experience of flying an aircraft, the exact systems of an A330 escape me, so I'm assuming something along these lines could happen?


(edit - I'm surprised civilian aircraft don't have to carry search and rescue beacons that activate on hitting the water and float?)

 

[Moonwalker]

The information regarding the cockpit voice recorder is not quite correct, as usual. The 30 minutes recording is an old standard. It is still mentioned basically because the last 30 minutes are recorded in high quality. But todays CVRs, especially those installed on Airbus, record 120 minutes all in all.

 

[Urwumpe]

Small update: The debris initially reported as from the Airbus, has now been reported to be not related to the accident. That means: back to the start. And again one day more lost in the race to find the flight recorders.

Also, to make the accident a bit more understandable, I have attached a page from the FCOM, which explains the first error message received: The automatic downmode of the flight control system from primary law to alternate law.

As you can see, this does not happen for small errors, and most causes are related to the hydraulic actuators and control surface and can be caused by heavy turbulence.

 

[Moonwalker]

It's actually called normal law rather than primary law. But this is just play of words.

Anyway, my doubts grow that we would ever be able to know what happened in detail. The more days go by, the more unlikely it gets to even find anything I think. Not to mention the black box especially if we consider the depth of the ocean. I fear the worst...