Airbus crash.

[vintage1]

Picked up this interesting link somewhere today.

More of a 'well it wasn't this, this or this, and it could have been that'

But interesting none the less.

http://www.weathergraphics.com/tim/af447/

[Air Head]

It is very obvious to me that there are some really smart people out there. I see now that I am not one of them. I guess as a weather forecaster he should be able to put this sort of report togeter, but as a holder of a pilots license, I thought I had a bit of a grasp on this sort of thing.

Very Very impressive work.....Ill get back to sanding some foam and winding motors..

Thanks for that though....Great work.

While I am here, could it be boiled down a bit to a bottom line as to what is thought to have happened? I imagine its there, I just cant read it as fast as it was put together....

Flew through a Thunder Storm ??? I think this says ???


Impressive

[kcaldwel]

Or maybe this?:

http://news.yahoo.com/s/time/20090603/wl_time/08599190242100

[HELModels]

I got a few things out of that Wx guys report:

1. weather was a factor
2. Airbus ROHS compliant - not good in lightning?
3. maybe tried to fly over storm and encountered + lightning strike
4. :(

[vintage1]

I think that., working backwards, it certainly - or almost certainly - had serious structural failure at altitude.

It was unable to send any human origin radio signals. That in itself suggests not a slow sequence of events, but a single violent event with little warning.

Remember al lot of people with misplaced national pride, or a job to protect, want to see Airbus fail. Boeing is only beginning its own fly by wire program, and they do not use composites as much as Airbus, so its all grist to their mill to blame the electronics or the composites.

However if the software could be sent into weird land by an extreme attitude excursion..as might be encountered in a violent thunderstorm, that seems to be plausible.

I'll let the pundits have the last word, but it seems to me that an airliner at mach 0.7 or so going into an uncontrolled dive would very soon pass the point of no return.

Or it may simply have been ripped apart by extreme and highly localised turbulence.

Weather, the climatologists tell us, is getting bigger with global warming.

[rick.benjamin]

I heard something to the effect that the 2 debris fields
in relation to it's last position report
suggests an abrupt attempt to return to South America.

[Work in Progress]

It doesn't take global warming for thunderstorms to exist that can utterly overwhelm even the strongest aeroplanes. There are lots of sequences of events that may have led to the loss of this flight, and we may never know exactly what happened in this case. However, it is possible to address the general case.

Large thunderstorms are always dangerous. Lightning strikes are one hazard and have received a lot of attention in this case because the news media, like the general public, automatically think of lightning as the 'obvious' risk of thunderstorms, but complete aerodynamic upset, massive hail damage, overwhelming airframe icing, and/or catastrophic over-stressing of airframes are also possible.

Any aeroplane which for whatever reason flies into the heart of a large thunderstorm cell is at grave risk. Penetrating an active storm front depends on vectors from ground-based radar (of which there is none covering the mid-Atlantic) or use of on-board weather radar and other storm detection technology, such as lightning discharge sensors. Using these a crew may be able to navigate safely through the relatively benign clouds of a large frontal system using technology to avoid the active cu-nim cells which are invisibly embedded. If those aids are not available for any reason then it is a game of Russian roulette.

[vintage1]

Large thunderstorms are always dangerous. Lightning strikes are one hazard and have received a lot of attention in this case because the news media, like the general public, automatically think of lightning as the 'obvious' risk of thunderstorms, but complete aerodynamic upset, massive hail damage, overwhelming airframe icing, and/or catastrophic over-stressing of airframes are also possible.

.

However the great contribution of that article was to cast strong doubt on hail or icing at least.

But the global warming point was that thunderstorms capable of such damage are likely to become more frequent.

Whatever else may or may not happen, the real fact is that there is more energy in the atmosphere than there used to be.

[jfrickmann]

It could also be structural failure following heavy turbulence in combination with control surface input. That's what happened with AA587 - the one that crashed over Long Island after the rudder broke off. http://www.flyingmag.com/accidents/545/aa587-the-perils-of-flying-by-the-book.html

[vintage1]

Very good article. Thanks for that.

I'd read up the Fuji incident, but not that one.

Reminds me of that bitt in 'slide rule' where the R100 designers frantically went over their calculations on hearing that the servo assisted R101 had put in 'force limiting' on the rudders to prevent them being torn off..their simple mechanical system didn't need them. The pilot simply wouldn't be strong enough to move the rudders far enough to destroy them!

Anyway a ripped off tail will be one thing they will definitely be looking for. And ripped off engines too, as without a tail, its likely that the lateral forces would probably snap those off too.

However, I suspect that due to the location, they may never get to the bottom of this one. Not beyond reasonable doubt, anyway.

Keep the stuff coming in. I am always fascinated by forensic engineering as it were..

[Work in Progress]

However the great contribution of that article was to cast strong doubt on hail or icing at least.

But the global warming point was that thunderstorms capable of such damage are likely to become more frequent.

Whatever else may or may not happen, the real fact is that there is more energy in the atmosphere than there used to be.

I agree with all of that - just really wanting to make the general point about flight into thunderstorms always being exceptionally dangerous, as a lot of the general media seem to be reporting on the basis that modern airliners are designed to cope with anything the weather can do. Which is far from the case.

[vintage1]

I agree with all of that - just really wanting to make the general point about flight into thunderstorms always being exceptionally dangerous, as a lot of the general media seem to be reporting on the basis that modern airliners are designed to cope with anything the weather can do. Which is far from the case.

Well that's the usual 'don't frighten the horses, except with terrism, cos thats a vote winner' stuff.

I remember on flying to Johannesburg (in the bloody TAIL of a Jumbo, never again) being woken by the tail moving around, and I noticed we were turning and throttling back, and the horizon was full of flashes and dark clouds. We stooged around a bit and picked a route between them that wasn't TOO bad. We thumped and bumped, and the tail whizzed up and down a few miles it seemed. Vile. But safe.


I remember being surprised that a mere thunderstorm caused such concern...wasn't till many years later and after seeing those things at ground level..nothing beats a good tropical thunderstorm for sheer ferocity - I realised why.

[Work in Progress]

It seems to be a reasonable conclusion from the debris pattern that the Airbus came apart in a big way at fairly high altitude and high speed, rather than descending in mainly one piece. That could have many first causes, of course. Any major structural failure in the cruise, regardless of first cause, could lead to a high speed tumble and comprehensive break-up.

[vintage1]

yes.. bits seem to be widely scattered..seem to be.

[Jurgen Heilig]

...
Keep the stuff coming in. I am always fascinated by forensic engineering as it were..

The pilot sent a manual signal at 11 p.m. local time saying he was flying through an area of "CBs" - black, electrically charged cumulonimbus clouds that come with violent winds and lightning. Satellite data has shown that towering thunderheads were sending 100 mph (160 kph) updraft winds into the jet's flight path at the time.

Ten minutes later, a cascade of problems began: Automatic messages indicate the autopilot had disengaged, a key computer system switched to alternative power, and controls needed to keep the plane stable had been damaged. An alarm sounded indicating the deterioration of flight systems.

Three minutes after that, more automatic messages reported the failure of systems to monitor air speed, altitude and direction. Control of the main flight computer and wing spoilers failed as well.

The last automatic message, at 11:14 p.m., signaled loss of cabin pressure and complete electrical failure - catastrophic events in a plane that was likely already plunging toward the ocean.

"This clearly looks like the story of the airplane coming apart," the airline industry official told The Associated Press. "We just don't know why it did, but that is what the investigation will show."

French and Brazilian officials had already announced some of these details, but the more complete chronology was published Wednesday by Brazil's O Estado de S. Paulo newspaper, citing an unidentified Air France source, and confirmed to the AP by the aviation industry source.

[JetPlaneFlyer]

There is some plausible speculation that the plane stalled as a result of reduction in airspeed (which apparently is standard practice when flying through storms) coupled with severe turbulence.
Word is that Airbus are sending out a safety bulletin to all A330 operators reminding them of the need to maintain "adequate thrust and correct attitude" when flying through turbulence. If this is the case it certainly sounds like they are already pretty sure what caused the tragedy.

I guess it's quite possible that the plane, even if flying with a reasonable margin above stall speed in level flight, could have stalled if it flew into a area of rapidly rising air, or experienced a strong wind gust from the rear. Normal stall warning devices would be useless in this scenario, the stall could be sudden and violent. Even if the crew took the correct action I suppose that in a high speed stall at 35,000 feet the aircraft could have quickly exceeded its Vne and/or been exposed to loadings outside of design limits causing structural failure :( ..
The reported automated distress messages fit well with such a scenario.

http://www.timesonline.co.uk/tol/news/world/europe/article6430398.ece

Steve

[Work in Progress]

Steve,
That's all fair comment, and I can see why Airbus would wish to issue such advice, but they may be whistling in the wind even so. The real issue with operating at 35,000 feet in a determinedly subsonic aeroplane tends to be that the safe upper speed is not set by Vne but by Mmo, limiting Mach number. With high wing loading (and there was still an awful lot of fuel on this flight) the classic "coffin corner" gap between Mmo and 1G stall can be very narrow.

Vertical gust loads can give an aeroplane a savage beating, and the faster it is flying the more savage the beating because the onset is quicker as the airframe rapidly crosses the boundary between vertically neutral air and rising air, or moves from strong wing into neutral air. The shock becomes more 'square-edged', if you like. Even cruising along below a normal cumulus cloud street in light aeroplanes at 120 knots I've seen 3G or 4G shock loads, and in a big Cb you can see 90 or 100 knot updrafts. Airbuses and their like are designed to pretty modest ultimate loads, which is why the generic turbulence advice is to reduce speed... it is generally better to have the aeroplane stall at less than the ultimate load G limit, than to break the wings off. Of course, if it's *that* turbulent, recovering from a stall and the ensuing unusual attitude may be complicated by other factors, and if you are up in the tighter recesses of Coffin Corner, any sort of normal stall recovery attempt may rapidly lead to exceeding the maximum Mach number.

All good reasons to steer clear of Cb systems, alas.

[fnev]

Steve,
That's all fair comment, and I can see why Airbus would wish to issue such advice, but they may be whistling in the wind even so. The real issue with operating at 35,000 feet in a determinedly subsonic aeroplane tends to be that the safe upper speed is not set by Vne but by Mmo, limiting Mach number. With high wing loading (and there was still an awful lot of fuel on this flight) the classic "coffin corner" gap between Mmo and 1G stall can be very narrow.

Vertical gust loads can give an aeroplane a savage beating, and the faster it is flying the more savage the beating because the onset is quicker as the airframe rapidly crosses the boundary between vertically neutral air and rising air, or moves from strong wing into neutral air. The shock becomes more 'square-edged', if you like. Even cruising along below a normal cumulus cloud street in light aeroplanes at 120 knots I've seen 3G or 4G shock loads, and in a big Cb you can see 90 or 100 knot updrafts. Airbuses and their like are designed to pretty modest ultimate loads, which is why the generic turbulence advice is to reduce speed... it is generally better to have the aeroplane stall at less than the ultimate load G limit, than to break the wings off. Of course, if it's *that* turbulent, recovering from a stall and the ensuing unusual attitude may be complicated by other factors, and if you are up in the tighter recesses of Coffin Corner, any sort of normal stall recovery attempt may rapidly lead to exceeding the maximum Mach number.

All good reasons to steer clear of Cb systems, alas.


You sum it up very well within the (little) information available today. The crew was a 3 men crew with a senior captain (over 10,000 hours) a senior pilot (6,000 hours) and a junior pilot (2,000 hours). It seems that the captain was not at the controls when all the known events took place…

[HELModels]

No airspeed indicator.

[JetPlaneFlyer]

No airspeed indicator.

I'm sure it had lots of air speed indication but stall is not only related to airspeed. Given a sudden and strong enough updraft the plane could have stalled even if airspeed was well above normal stall speed in level flight for the altitude the plane was at.

The idea I've heard mentioned that the air speed indicators had somehow iced up does not sound likely because at that altitude and temperature liquid water could not exist so ice could not build up.... and there was no record of air speed indication failure.

A stall does appear the most likely explanation right now but things could change as further evidence comes to light........

Steve

[Work in Progress]

I'm sure it had lots of air speed indication but stall is not only related to airspeed. Given a sudden and strong enough updraft the plane could have stalled even if airspeed was well above normal stall speed in level flight for the altitude the plane was at.

The idea I've heard mentioned that the air speed indicators had somehow iced up does not sound likely because at that altitude and temperature liquid water could not exist so ice could not build up.... and there was no record of air speed indication failure.

A stall does appear the most likely explanation right now but things could change as further evidence comes to light........

Steve

Thinking specifically of Airbus issues rather than generic aviation issues, it's just occured to me that the Airbus family meters AoA directly for the benefit of the flight computers, as well as having pitot based airspeed indication.

The aeroplane also has alpha limiting protection built into the flight control software, meaning that nothing the pilot can do can stall the wing, providing a) that the systems are functioning correctly, and b) that the weather is within a range of conditions suitable for flight by the type. However, in heavy turbulence it is quite possible for an aeroplane to be stalled directly by gust effects regardless of control inputs, whether those inputs are computer-applied or human-applied.

[vintage1]

I am sure they will be running simulations right now to see what happens to the software if more violent than anticipated excursions take place.

Any news on the wreckage?

Oh.. I thought to look. This is a balanced enough report
http://news.yahoo.com/s/ap/20090604/ap_on_re_la_am_ca/brazil_plane

[Work in Progress]

"Aviation analyst Bill Voss said if the plane was traveling too fast in heavy turbulence, it could break apart. If traveling too slow, it could stall."

Correct, but as I was trying to drive at in my earlier post, if the weather is bad enough and you are at high altitude you reach a point where the definitions of "too fast" and "too slow" actually meet and overlap.

[Jurgen Heilig]

"Aviation analyst Bill Voss said if the plane was traveling too fast in heavy turbulence, it could break apart. If traveling too slow, it could stall."

Correct, but as I was trying to drive at in my earlier post, if the weather is bad enough and you are at high altitude you reach a point where the definitions of "too fast" and "too slow" actually meet and overlap.

The point were "too fast" and "too slow" meet, is the tip of your flight envelope. They can't overlap, you are just outside of the flight envelope then.

Modern airliners all have some kind of "electronic aids":

http://en.wikipedia.org/wiki/Flight_envelope_protection

but if nature acts up enough, even the best system (including the pilots) might not be able to keep an aircraft out of trouble.

:) Jürgen

[vintage1]

The point were "too fast" and "too slow" meet, is the tip of your flight envelope. They can't overlap, you are just outside of the flight envelope then.

Modern airliners all have some kind of "electronic aids":

http://en.wikipedia.org/wiki/Flight_envelope_protection

but if nature acts up enough, even the best system (including the pilots) might not be able to keep an aircraft out of trouble.

:) Jürgen

I think what WIP meant, was that the aircraft was forced, or found itself, outside the tip of that envelope..too fast to be safe, and too slow not to stall.

[Jurgen Heilig]

Well, if the weather is really bad, I would either go to the top edge of the flight envelope to avoid it, or stay well within the flight envelope, so that the weather won't knock me out of the envelope.

:) Jürgen

[Work in Progress]

The only safe thing to do is not to enter such a system You might get on top of a small thunderstorm but you can't get above a major cu-nim front. The tops can go to twice the ceiling of a commercial airliner. The flight enevlope at high altitude becomes much smaller than at low level, so you may not have the luxury of simply choosing a speed that will enable you to handle the weather that is ahead.

It you fly into heavy weather at high altitude there may not be any safe speed. By that I mean that a speed slow enough to prevent structural damage may actually be below the stalling speed. Remember that at high altitude your indicated air speed, which is the measure relevant to stall speed for a given loading, varies dramatically from true airspeed, which is the measure relevant to the onset of vertical gust shocks. At 40,000 feet, 200 knots indicated airspeed is around 400 knots true airspeed.

Meanwhile, the speed of sound at that altitude is only about 575 knots true, around 275 knots indicated. I don't know the 1G stall for a heavily loaded A330 in clean cruise consideration but it won't be far off 200 knots. So if you do have any kind of upset at that sort of altitude, which ends with the nose down, it would be very hard not to exceed limiting Mach, with potentially disastrous consequences.

[Jurgen Heilig]

The only safe thing to do is not to enter such a system. ...

Fully agree, but sometimes those bad weather areas are obviously to big to divert around them. Other aircraft have been on the same route, same day without major problems.

:) Jürgen

[HELModels]

I'm sure it had lots of air speed indication but stall is not only related to airspeed.

I'm not so sure it had any indication of anything except failures.

[Work in Progress]

Fully agree, but sometimes those bad weather areas are obviously to big to divert around them. Other aircraft have been on the same route, same day without major problems.

:) Jürgen


No sensible pilot ever leaves himself without an alternative, and in commercial air transport you are explicitly required to plan your diversions.

They had the option of diverting back to Brazil, or many other places on the eastern seaboard of South or Central America. If for whatever reason you are not equipped to avoid embedded CBs in a large storm front then you don't penetrate the storm front.

[JetPlaneFlyer]

I'm not so sure it had any indication of anything except failures.

There was no report of any failures until after the autopilot disabled itself, or if there were reports they have not yet been made public. The autopilot turning itself off would be the first signal sent out if the plane had stalled (or suffered a structural failure). The automatic failure messages that followed were consistant with a plane that was plummeting out of control then broke up.

Perhaps there was a problem with airspeed indication but nothing that's been made public so far really supports the theory. However the fact that Airbus appear to have issued guidance on what to do if airspeed indications are inconsistant does make one wonder if there is something they are not telling us?.

Steve

[vintage1]

I think the reality is that at one point, there are two conflicting airspeed indications. Perhaps the plane was in two pieces? :D

The short answer is that no one knows what happened, its not 'something they aren't telling us because they are covering up' ..its something they aren't telling us because they really do not know what it is'.

As far as being able to avoid the weather goes, its not that simple or that easy.

First of all, there is the commercial restraint. Pilots are not paid to not make schedules and deliver their passengers on time to where they are going.

Secondly, storms like this are common enough: Yes, pilots normally go off autopilot, and use whatever they have to navigate the best route through them, but they expect some buffeting.

Third, these storms are very dynamic I understand..conditions that look fine to start with, can rapidly shift and a good way in can become a trap with no way out but strap down and take the punishment.

By the very nature of statistics, a pilot or aircraft may eventually encounter a set of circumstances that are just plain bad luck..the one in ten thousand chance. The issue here is to establish if this was the sole cause, or whether equipment failure or pilot error contributed.

The speed with which the accident developed is of interest. There was no report of equipment malfunction - though I accept that radio transmission may have been compromised. No emergency was declared. One minute the plane is entering a storm, the next its on its way down with equipment out, conflicting indications from the rest, unpressurised, and dying.

Obviously at some point it fell out of the air: As to whether that was BECAUSE it fell apart first, or because some other factor caused it to stall or exceed limits due to pilot or avionics failure, is the only issue.. In the absence of evidence its all mere speculation.

[Jurgen Heilig]

No sensible pilot ever leaves himself without an alternative, and in commercial air transport you are explicitly required to plan your diversions.

They had the option of diverting back to Brazil, or many other places on the eastern seaboard of South or Central America. If for whatever reason you are not equipped to avoid embedded CBs in a large storm front then you don't penetrate the storm front.

Turning back may be an option, but as mentioned before, this was not the only aircraft on this route that day and as vintage1 put it:

... there is the commercial restraint. Pilots are not paid to not make schedules and deliver their passengers on time to where they are going.

:) Jürgen

[JetPlaneFlyer]

I think the reality is that at one point, there are two conflicting airspeed indications. Perhaps the plane was in two pieces? :D

The short answer is that no one knows what happened, its not 'something they aren't telling us because they are covering up' ..its something they aren't telling us because they really do not know what it is'.



I never suggested a cover up.. Obviously Airbus cant tell the public everything they know the instant they know it. However todays announcement by Airbus to the effect that there is a known an recurring problem with A330 sirspeed indication confirms my suspician that they did 'know something', hence the reason for the alert.

If it contributed to the crash time will probably tell..

From BBC web site;
Mr Arslanian (Airbus spokesman) confirmed that the missing jet had had a problem calculating its speed, adding that it was a recurring problem on the A330s and that Airbus was undertaking a replacement programme.

"We have seen a certain number of these types of faults on the A330," Mr Arslanian said. "There is a programme of replacement, of improvement."


Steve

[Jurgen Heilig]

Search teams have found the complete vertical stabilizer of AF447. Question of course is, whether the part came off in flight or on impact.

Without a vertical stabilizer, any aircraft is doomed - also see AA587:

http://www.rvs.uni-bielefeld.de/publications/Reports/CrashOfAA587.pdf

[JetPlaneFlyer]

Search teams have found the complete vertical stabilizer of AF447. Question of course is, whether the part came off in flight or on impact.

Without a vertical stabilizer, any aircraft is doomed - also see AA587:

http://www.rvs.uni-bielefeld.de/publications/Reports/CrashOfAA587.pdf

And even if it did break off in flight did it directly cause the crash or was it a secondary effect of some other upset condition like a stall?

I dont suppose we will have an answer until they find the flight data and voice recorders.

Steve

[CloudyIFR]

Wasn't there a B52 during Vietnam that made it home with little or no vertical flying surface? I'm sure that's quite rare!

Curtis
Montana

[Jurgen Heilig]

Wasn't there a B52 during Vietnam that made it home with little or no vertical flying surface? I'm sure that's quite rare!

Curtis
Montana

Ok, if the rear fuselage has large enough vertical sidewalls and the rest of the vertical stabilizer creates enough drag, you might get away with it:

http://www.youtube.com/watch?v=gGkKSk6fAvI

[Shedofdread]

From the vid, it appears the spoilers are deployed. This presumably will damp the aircraft in yaw. The Hortens used to do a similar thing with their designs. If they started to dutch roll, by opening both of the drag rudders, the oscilation was damped out.

S

[Cap_n_Dave]

As far as being able to avoid the weather goes, its not that simple or that easy.

Another possibility is that the weather radar may have been impaired by a lightning strike, reducing or eliminating the possibility that the aircrew could fly around the major convective cells.


No emergency was declared.

This piece of information is interesting. On the one hand, a variety of television interviews have documented pilots stating that 'communication is the last priority.'

On the other hand, this issue could indicate that the situation deteriorated very rapidly. It is difficult to say.

The automated maintenance transmissions are interesting ... I sincerely hope the investigative team is able to locate one or both of the black boxes in order to put the story together.

Of note there are reports today that 2 names on the passenger manifest match those on a terrorist watch list. So the possibility of terrorism is evidently not yet ruled out. Autopsies would hopefully confirm or deny a bomb as a cause through discovery of explosive residue on victims.

Time will tell.

[harveyweewax]

Wasn't there a B52 during Vietnam that made it home with little or no vertical flying surface? I'm sure that's quite rare!

Curtis
Montana

From this web page: http://www.talkingproud.us/HistoryB52NoTail.html

"On January 10, 1964, Boeing civilian test pilot Chuck Fisher and his three man crew lost their tail, the tail of their B-52H Stratofortress that is, at about 14,000 ft. over northern New Mexico's Sangre de Christo mountains."

"Six hours later and after a lot of engineering on the ground and in the air, Fisher brought his B-52 home, with the coveted data."

One tough airplane.

Regards,

Sven

[Brandano]

...
One tough airplane
...

Err.... one wonders how it came to lose the tail in turbulence, though..

[harveyweewax]

Err.... one wonders how it came to lose the tail in turbulence, though..

Per the web page I previously linked to: "A Boeing memorandum of January 24, 1964 purportedly said the following:

"... flown through an area containing the combined effects of a (wind) rotor associated with a mountain wave and lateral shear due to airflow around a large peak ... Gust initially built up from the right to a maximum of about 45 feet per second (TAS), then reversed to a maximum of 36 feet per second from the left, before swinging to a maximum of about 147 feet per second from the left followed by a return to 31 feet per second."
Our calculation of 147 feet per second is about 100 mph.

Fisher would later recount, as reported in Aerospace Safety, April 1964:

"As the encounter progressed, a very sharp- edged blow which was followed by many more. We developed an almost instantaneous rate of roll at fairly high rate. The roll was to the far left and the nose was swinging up and to the right at a rapid rate. During the second portion of the encounter, the airplane motions actually seemed to be negating my control inputs. I had the rudder to the firewall, the column in my lap, and full wheel, and I wasn’t having any luck righting the airplane."

Also "....data showed that turbulence would over-stress the rudder connection bolts, causing a rudder and then a tail failure. This report said the bolts were strengthened which fixed the problem"

The article also states that the Buff was repaired and was still in service as of 2007.

I wonder if something similar happened to the Airbus.

Regards,

Sven

[JetPlaneFlyer]

I wonder if something similar happened to the Airbus.


Unlikely as there are no mountains or peaks to cause wind rotors or wave turbulence in the middle of the Atlantic. I could be wrong but I would suspect that the type of storm the plane was in would cause mainly vertical wind velocities rather than anything severe horizontally... but i stand to be corrected if mistaken.

But perhaps if the pilot stomped on full rudder to correct some upset flying condition?...........

Steve

[CloudyIFR]

But perhaps if the pilot stomped on full rudder to correct some upset flying condition?...........

Steve

Hmmm, that goes back to the Airbus crash out of New York right after 911.

Curtis

[harveyweewax]

Unlikely as there are no mountains or peaks to cause wind rotors or wave turbulence in the middle of the Atlantic.

Well, duh :) I meant similar in effect. My bad for not being very clear.

Regards,

Sven

[vintage1]

Well, duh :) I meant similar in effect. My bad for not being very clear.

Regards,

Sven

And his point was that lateral wind shear, which you get off mountains, doesn't happen much in thunderstorms.

I.e. there isn't any 'similar in effect'.

Lateral wind shear is probably responsible for more crashes..I suppose people are not used to it, and maybe they don't stress for it either. Its typically around mountains, or crossing a jet wake..

[harveyweewax]

And his point was that lateral wind shear, which you get off mountains, doesn't happen much in thunderstorms.

I.e. there isn't any 'similar in effect'.

Lateral wind shear is probably responsible for more crashes..I suppose people are not used to it, and maybe they don't stress for it either. Its typically around mountains, or crossing a jet wake..

Ah, I understand now. Thanks for the explanation.

Regards,

Sven

[JetPlaneFlyer]

I read that the A330 fly-by-wire computer is programmed to limit rudder movement to prevent overstressing the vertical stab. It does this by looking at the airspeed and (regardless of pilot input) reducing maximum rudder deflection as airspeed increases so that the aerodynamic force generated stays within structural limits.
So it should have been 'fool proof'. The pilot should be able to stomp on the rudder pedals all he wants without fear of vertical stab failure.. But if the pitot tube that fed the computer it's airspeed was iced up.... :eek:

Just one of many possibilities at this stage i guess.

Steve

[Brandano]

Actually, as far as I know reduced control laws still maintain yaw dampening and a few other structural safeguards. Notwithstanding the seriously misleading anti-airbus trolling I have seen posted elsewhere, the fly by wire setup of the A3xx series ultimately degrades to a point where the plane is completely in the hands of the pilots. there's no point where the plane crashes because it won't do what the pilot tells it to do.

[CloudyIFR]

But if the pitot tube that fed the computer it's airspeed was iced up.... :eek:

Just one of many possibilities at this stage i guess.

Steve


I think Pitot tube icing in the mid 30's flight levels just isn't going to happen. The temperature is always below freezing above FL240 and in the mid 30's and above the temperature will be well below minus 20C and airframe or pitot icing just doesn't happen. At least with my 6,500 hours of experience. But I'm still learning! :)

Curtis
Montana

[WTFLYR]

I think Pitot tube icing in the mid 30's flight levels just isn't going to happen. The temperature is always below freezing above FL240 and in the mid 30's and above the temperature will be well below minus 20C and airframe or pitot icing just doesn't happen. At least with my 6,500 hours of experience. But I'm still learning! :)

Curtis
MontanaFlying at least an hour every day, for around 18 years!
Are you an airline pilot?

As for the rudder, there was an airline crash near where I live something like 10 years back, where the rudder stuck at defelection. Hopewell PA for search.

[Brandano]

possibly one of the string of accidents affecting the boeing 737 in the past? http://en.wikipedia.org/wiki/Boeing_737_rudder_issues
As far as I know the defect has been corrected.

[vintage1]

All this icing up of Pitot tubes is pure speculation based on ONE piece of evidence: namely that thelas data that the aircraft airspeed sensors sent back was conflicting data ..Now I don't know where they are, but if they are in the wings, and it was finless, rudderless and spinning..they probably would, wouldn't they?

The original link that I posted was a clear meteorological analysis that was very definite that icing was extremely unlikely.

I really think that it was either a lightning strike that totally messed the avionics, or simply that it hit turbulence it wasn't designed to handle. And tore apart.

Or there was a bomb on board.

But no one has claimed it, which rather reduces the terror impact.

Of course you might be a reader of thrillers, in which case it was murder on someone aboard :D

[JetPlaneFlyer]

Vintage,
What about the reports of problems with air speed indication on the A330 up to a year before this accident? And the fact that Airbus had already started replacement program?... This surely indicates that there is slightly more to the air speed indicator error theory than simply the transmitted data.

It is still no more than a possibility though and yes, icing would appear highly unlikely if not impossible at that altitude.

Steve

[CloudyIFR]

Flying at least an hour every day, for around 18 years!
Are you an airline pilot?



Airline pilot, no, I like my job. Ha ha.

Charter/Air Ambulance pilot yes.

Single Engine and Twin Engine Cessna's.
Piper Cheyenne's
Learjet 24D.

All single pilot Capt, well except for the Learjet.

Curtis
Montana

[nfhill]

Actually, as far as I know reduced control laws still maintain yaw dampening and a few other structural safeguards. Notwithstanding the seriously misleading anti-airbus trolling I have seen posted elsewhere, the fly by wire setup of the A3xx series ultimately degrades to a point where the plane is completely in the hands of the pilots. there's no point where the plane crashes because it won't do what the pilot tells it to do.

This is not an Airbus bash, but I believe this is not true. The Airbus flight control computers are always the final authority. All pilot control inputs are always subject to the flight control computer approval and can and will be overruled if the flight control computers don't agree.

This is the heart of the controversy about whether Airbus crashes are due to pilot error or computer error. So far, all have been ruled as pilot error.

[Brandano]

What I am referring to is this list:
http://www.airbusdriver.net/airbus_fltlaws.htm
As you will see, if there are no failure then the plane will obey its control laws, which prevent the pilot from entering into dangerous situations. If any system failure is detected the control laws degrade to the point where the pilot has direct control of the plane. Incidentally, I think that the FBW preventing the plane's stall played a major part in the successful ditching of US Airways Flight 1549

[nfhill]

One could say (a detractor) that this is like reading from a MS manual about how well Windows works.

I'm not personally acquainted with the Airbus flight control system. I'm just relating the industry 'buzz'. Particularly the talk after the '94 crash at Toulouse France. I was working at the DASA factory in Germany that day. You can well imagine how much 'discussion' took place afterwards. While the official cause was ruled as pilot error, there were many people in the industry that disagreed. There are professional airline pilots that will not fly Airbus planes.

For what it's worth, because the vertical stabilizer was found intact, it's worth noting that the rudder is not controlled 'by wire' and it is possible for the pilot to over control the rudder and cause the vertical stab to break off on these aircraft.

[WTFLYR]

Maybe not the problem in this case, but there's always engine problems. This just reminded me of a friend's experience. He was on an Airbus sitting on the wing seat (I think A330) coming back to the States from France, that had not gone too far from the airport. He was looking at the engine, and saw flames shooting out intermittently. :eek: He notified a stewardess, and they went to the cocpit. The plane turned back to France.

[Flight Engineer]

guys I've not posted on this thread as I keep my work and hobby separate as much as possible however:

The strongest mountain wave activity I've encountered in 20 years of military and civilian aviation was in the middle of the south atlantic ocean where two jet streams that had passes over the Andes merged and caused severe clear air turbulence and constant TAT fluctuations of +- 15c.

We don't use the term lateral wind shear. All wind shear is circular in nature the most dangerous being micro burst activity at low level. Often recognisable by positive shear (increasing head wind and up draughts) followed by negative shear (increasing tail wind and down draughts).

Similar phenomena may be experienced above a young growing CB.

The ITCZ can be testing sometimes. In the RAF I flew Brize to Ascension Island and back at least twice a month for 6 years transiting the ITCZ each time. My record was 200nm off track to navigate around the weather. other times we could get through with no deviation.

The A330 has a history of TAT and Pitot tube icing. The sequence of ACARS messages was immediately recognised as being the same as other Pitot tube icing events that did not result in accidents.

Last week EASA issued a safety bulletin advising airlines and manufacturers to have in place and remind crews of the correct procedures for erroneous airspeed indications.

All the commercial jets I have either flown or taught have Rudder limiters, either mechanical or FBW. They offer some protection. However there is a maximum certified speed for full control inputs called Vra. Above this speed all structural bets are off. Below this speed there is no guarantee for repeated end to end inputs (this is what did for the AA airbus, it was mishandling unfortunately taught by the airline).

AF have hastened the replacement of all Pitot tubes to a newer model on all their AB fleet. This mod was already in progress before this incident.

What exactly happened? We will know if and when the DVDRs are recovered.

[CloudyIFR]

Flight Engineer,

Ascension Island, I've been there. I was a radio operator/technician on EC-135's better know as ARIA, the big ole snoopy nose 707's. What a beautiful place!

Curtis
Montana

[Flight Engineer]

Flight Engineer,

Ascension Island, I've been there. I was a radio operator/technician on EC-135's better know as ARIA, the big ole snoopy nose 707's. What a beautiful place!

Curtis
Montana

Used to see them quite often. Normally the precurser to a fireworks display, best viewed from the Volcano Club.
:-)

I was on the RAF L1011s

[CloudyIFR]

Oh boy, the Volcano club!

Happy hour Red Stripe beer and you get 20 of them for $5.00!

Curtis

[JetPlaneFlyer]

Apparently the preliminary report is going to point the finger at iced up pitot tubes as suggested earlier in this thread. Probably blocked up by airborne ice crystals rather than the freezing of liquid water (which as pointed out could not exist at the altitude and temperature).

Airspeed indication failure caused the autopilot to disengage handing control over suddenly and without any warning to the pilot in the middle of a storm with false airspeed indication, flying in high altitude thin air, in the dark and with a cockpit full of warning sirens and flashing lights.
Apparently the procedure is to ignore the air speed indication and other warnings and fly the plane straight and level at the appropriate throttle setting for cruise flight. Basically trust the plane's trim and physics to maintain correct airspeed. Easier said than done in an emergency situation.

The worst thing is that this is not the first time it's happened but on previous occasions the pilots have managed to cope.

[jatur]

I received this in an email the other day. Anyone know how authentic it is? Could well be someone pushing a vested interest.
http://bellaciao.org/en/spip.php?article18909
If only partly true, it is a bit scary!.

[vintage1]

I received this in an email the other day. Anyone know how authentic it is? Could well be someone pushing a vested interest.
http://bellaciao.org/en/spip.php?article18909
If only partly true, it is a bit scary!.

Well there is a very bitter war between Boeing and Airbus, and selective editing of cats to paint a scary picture is just part of it. As they point out right at the start, the number of people killed in Boeing aircraft is similar.

All planes are flawed in one way and another, the whole point of accident investigation is to trace the chains of events that cause the final crash, and see where if anywhere, procedures can be changed, training amended or redesign or modification incorporated.

I didn't like the way that article was structured. All materials can fail, and they have cherry picked instances there in what appears to be a deliberate attempt to cast doubt over the use of composites in airliners.

What seems to be to be relevant is that there is some doubt over the stability of the rudder. It CAN be and has been able to move in such a way as to overstress the tail. Once over stressed, its not fair to blame the material for breaking when beyond design limits, which the article seems to do.

Personally I see it as a ruse to use what possibly is a real problem - how the rudder works - and turn it into a pseudo problem - the use of composites - because Boeing presumably have metal tails, ergo 'Boeing is safer'..

And another very nasty point. Boeing didn't do the main composite research in the US, NASA did, so to say that Airbus' research data is 'not as open' as NASA's and hint at commercial secrecy and a cover up, is pretty vicious. You can be sure that if Boeing had done, they wouldn't have published the results either.

Even the most balanced of the comments, is slanted:

While the overall number of accidents and fatalities are not disproportionate to the crash experience of Boeing aircraft, three of the Airbus crashes involved a separation of the composite vertical stabilizer (tail fin) from the fuselage. Five hundred, or one in five of the Airbus deaths, including 228 from Air France Flight 447, resulted from these three crashes.

Translated, Airbus aircraft have a no worse (perhaps they have a BETTER?) crash record than Boeings. 'Not disproportionate' is a funny phrase to use. Perhaps selected because, in fact overall Airbus' safety record is BETTER than Boeing?

I didn't like their 'Occams Razor' use either. A fairly complete misapplication of the principles of philosophy to engineering analysis.


So yes, whilst there is some useful information there, pointing at the rudder/fin failure as probably the first primary structural failure, there is no justification to cast doubt on the use of composites: Far more relevant is to work out WHY it separated.

I.e. was it a design or control flaw that resulted in excessive control movement, or was the plane simply overstressed by the nature of what it encountered.

[nfhill]

Without the flight data recorders, any conclusion about the cause of this crash (especially by uninformed layman like us) is speculation.

It is true that Airbus composite tails have had structural failure due to delamination and undetected voids during manufacture. It's true that Boeing has been slower to adopt the use of composites in critical structures.

The question of what inspection techniques are appropriate to detect delaminations is best left up to the experts. Inspecting composite structures after assembly is a tricky problem because the best inspection technology requires access to both sides of a layup and that isn't possible after assembly.

It's unlikely that either company has 'secret' knowledge on composite technology.

I sincerely hope the industry in general, and Boeing in particular, has adequate knowledge of composite's performance: the new Boeing 787 is primarily composed of composites. I'd really like them to stay profitable enough to pay my pension some day!

As for the relative safety records of Airbus vs Boeing, there are actual statistics kept and published regularly in the industry. One should be able to find this information. For what it's worth, the last time I saw the published safety data, in the mid '90's, Boeing aircraft had a better safety record.

[vintage1]

I heard a bit of news..apparently they are claiming it broke up on impact, not in the air.

http://news.bbc.co.uk/1/hi/world/americas/8131689.stm

[vintage1]

Another snippet. They have detected a beeping black box allegedly. Though strangely I cant find any online reports..heard it on teh beeb a couple of days ago? Maybe it was a stale story..

[Cap_n_Dave]

Another snippet. They have detected a beeping black box allegedly. Though strangely I cant find any online reports..heard it on teh beeb a couple of days ago? Maybe it was a stale story..

I heard a report about a beeping black box. I got excited that it might be from the Air France crash. As I listened to the report, they went on to state it was from the more recent Airbus crash off the coast of Africa.

[JetPlaneFlyer]

I heard a bit of news..apparently they are claiming it broke up on impact, not in the air.

http://news.bbc.co.uk/1/hi/world/americas/8131689.stm

This does not quite hang together for me.. I'm no aircrash investigator but the photo of the plane's galley unit intact, undeformed, and complete with drawers full of food still mounted in on their runners does not look like what I'd expect too see if the plane had impacted the water in one piece at high speed :confused:

Steve