Air France plane missing?

[beachfront]

Well you can e.g. look at the aviation safety statistics here, showing all the multi-engine jetliner accidents of 2005 (preceding years are also available on the same source). Using 2005, there were 35 accidents with a total of 1059 people killed. Of these 35 accidents, 6 involved Boeing aircraft, and none an Airbus. Have a look at page 9 of that report, you'll find a tabel with fatal accidents broken down by manufacturer. Here's an excerpt showing the two companies under discussion here for "cheap" designing...

1999: Airbus: 0 Boeing: 5
2000: Airbus: 2 Boeing: 3
2001: Airbus: 1 Boeing: 6
2002: Airbus: 0 Boeing: 7
2003: Airbus: 0 Boeing: 3
2004: Airbus: 0 Boeing: 2
2005: Airbus: 0 Boeing: 6

Cheers

m.

You can take it one step further to help clarify things...
Per the Boeing/Airbus websites

Since 1980 - using this year as a cut off for commercial aircraft in service -- up to 2007

Boeing - approx 13,600 orders and 10,852 deliveries
Airbus - Approx 9,000 orders and 5050 deliveries

This does not include any planes built before 1980 that may have been in service during any losses

[Leightman]

Antennae

Thanks P3: Vstab only has HF and VOR antennas. The rest of the antennas are on the tube, either upper or lower.

ACARS uses which antenna?

[Leightman]

Victim injuries; scenario hypothesis

Wannabe quotes in #1480: "3) Broken arms (mid arm) and legs (femur/thighbone): The fractures found also indicates a typical crash with passengers still inside the cabin..."

This info is a bit different than earlier reports that included lack of clothing. My point here is that fractures in #3 above are implicitly associated with impacts similar to a crash landing, where the longitudinal axis of the plane at impact is more or less that of normal flightm bnot completely vertical or sideways. This is only a small clue at this point but does suggest a scenario.

I for one would like to suppose for the time being that the pilots were not average, or only competent, but that their performance was exemplary. I prefer to think all airline pilots are very good at what they do. I am entertaining the hypothesis that the aircraft did lose its vertical fin due to whatever cause, but that somehow the pilots managed to maintain a semblance of control and made it through and out (at least for a short period of time) of the turbulence that apparently contributed to their situation. I am further wondering whether they managed to initiate a semi-controlled, non-standard emergency descent, and to reduce airspeed, and that a subsequent episode of turbulence made them lose control for a final time. I think this scenario could be an unlikely but possible sequence that might help explain the amount of time ACARS continued to broadcast, the hypoxic tooth color (the result of a slower rate of descent than a standard emergency descent, due to compromised controls, and a longer period of time at altitude), and the large pieces of debris (galley). It certainly appears the fuselage did break up, with a portion impacting hte ocean at high speed, and another portion impacting at a much slower speed. Throw darts if you like; certainly it is just an unlikely supposition at this point. But the most common sequences conflict with some of the information we now have.

[Fear_of_Flying]

Another article about the tail fin, an idea that is gaining traction in the media. From today's CS Monitor:

http://www.csmonitor.com/2009/0619/p02s01-usgn.html

[P3_Super_Bee]

ACARS uses which antenna?

Depends. Normally overland VHF, Overseas SATCOM, and polar routes HF. Not all aircraft equipped with HF Datalink.

[wannabe_A&P_girl]

I for one would like to suppose for the time being that the pilots were not average, or only competent, but that their performance was exemplary. I prefer to think all airline pilots are very good at what they do. I am entertaining the hypothesis that the aircraft did lose its vertical fin due to whatever cause, but that somehow the pilots managed to maintain a semblance of control and made it through and out (at least for a short period of time) of the turbulence that apparently contributed to their situation. I am further wondering whether they managed to initiate a semi-controlled, non-standard emergency descent, and to reduce airspeed, and that a subsequent episode of turbulence made them lose control for a final time. I think this scenario could be an unlikely but possible sequence that might help explain the amount of time ACARS continued to broadcast, the hypoxic tooth color (the result of a slower rate of descent than a standard emergency descent, due to compromised controls, and a longer period of time at altitude), and the large pieces of debris (galley). It certainly appears the fuselage did break up, with a portion impacting hte ocean at high speed, and another portion impacting at a much slower speed. Throw darts if you like; certainly it is just an unlikely supposition at this point. But the most common sequences conflict with some of the information we now have.

I have spoken to my friends and family that work in the industry. They all agree, my friend with about 30 years A&P and avionics experience in particular, that the vertical fin departed the plane due to overspeed and inadvertant or perhaps unwanted rudder input. My friend thinks that the crew was working with inaccurate data. I have to tell you, this guy is a life-long mechanic, and he is not placing blame on the pilots. He and his high-seniority mechanic friends hypothesize basically the same situation that you have described above. They do not think the pitot tubes were faulty and that for some reason AF/AB is trying to use that as a diversion from any other possibilities.
Leightman, I think you are on the right track and I agree with you. Many people here may be reluctant to agree, but that's ok. We will have to see what the investigation reveals.

[Theoddkiwi]

I am a Licenced Aircraft Maintenance Engineer, and i dont think the Vstab snapped off first causing the crash.

My experience is in the Avionics field, and have a pretty comprensive understanding of how the various sensors and electronics work, and how the failure of those sensors would affect many of the components within the aircraft systems.

Loss of air data either by icing or computer failure is the simplest and most plausible explanation. I see both scenarios in my proffesional experience on a regular enough basis to be comfortable that the combination of these will make it difficult for a pilot to fly an aircraft particularly at night in a storm.

Occams Razor, is the principle that "entities should not be multiplied unnecessarily." The principle states that the explanation of any phenomenon should make as few assumptions as possible, eliminating those that make no difference in the observable predictions of the explanatory theory.

We have photos of a largely intact Vertical Stab, so people have now assumed that it fell off causing the crash.

When multiple competing hypotheses are equal in other respects, the principle recommends selecting the hypothesis that introduces the fewest assumptions and postulates the fewest entities.the most simplest theory to an event.

Loss of the Vertical Stab is simple too complicated a scenario when combined with the other evidence, there are too many conflicting pieces to support it.
- The ACARS messages do not make any suggestion of a loss of the V Stab
- The Fact that the aircraft structure is still attached to the V Stab does not support the mountings failing.
- Just because we have photos of an intact V Stab does not mean it fell of first. It fell off, that is all we can be sure of, but when is any bodies guess.

The simplest scenario is:
The aircraft flew into and area of extreme icing within a storm system.
The pitot probe heating could not overcome the conditions (There have been previous examples of this happening in this type of aircraft), and there was sufficient blockage ( you really don't need much to cause a disagree)
The Blockage produce a differences in the pilots airspeed information.
The aircraft systems began to disengage as the data the computers use was becoming uncertain. (This is bread and butter avionics system behaviour)
The pilots took over manual flying and began trouble shooting, perhaps they forgot to fly it. (we have seen that time and time again)
The pilots got behind the aircraft and eventually lost control of the aircraft as systems continued to shut down.
The aircraft broke up after exiting the safe flying envelope and wandered past its structural design limits.

The Vstab on its own explains the crash, but not when combined with the other evidence.

Eg Why did TCAS fail if the V Stab fell off, it has nothing to do with it.

[mawheatley]

I am entertaining the hypothesis that the aircraft did lose its vertical fin due to whatever cause, but that somehow the pilots managed to maintain a semblance of control and made it through and out (at least for a short period of time) of the turbulence that apparently contributed to their situation. I am further wondering whether they managed to initiate a semi-controlled, non-standard emergency descent, and to reduce airspeed, and that a subsequent episode of turbulence made them lose control for a final time. I think this scenario could be an unlikely but possible sequence that might help explain the amount of time ACARS continued to broadcast, the hypoxic tooth color (the result of a slower rate of descent than a standard emergency descent, due to compromised controls, and a longer period of time at altitude), and the large pieces of debris (galley).

I'm not a pilot, but my understanding is that if the vertical fin were to depart completely the aeroplane would be uncontrollable. I'm fairly sure I read this after AA587. Air Transat managed to keep going because it was only the rudder and not the whole fin that went. As for ACARS sending out information and teeth turning pink, there would be time for that. Even in free fall it would take a few minutes to fall from 35,000ft. I'm tending to agree with your diagnosis, but I don't think they'd have had any chance at controlling the aeroplane. As I said, non-expert opinion here and I'd welcome backup/contradiction from one who is.

[Fear_of_Flying]

I disagree with elements of both wannabe's and theoddkiwi's posts above.

Wannabe:

They do not think the pitot tubes were faulty and that for some reason AF/AB is trying to use that as a diversion from any other possibilities.

This does not sound like a very professional opinion. One of the few scraps of evidence we actually have in this incident are the messages referring to airspeed indicator disagree. You have to have some other way to explain this if you're going to maintain the sensors were functioning properly, other than a cover-up theory.

Theoddkiwi:

The simplest scenario is:
The aircraft flew into and area of extreme icing within a storm system.
The pitot probe heating could not overcome the conditions (There have been previous examples of this happening in this type of aircraft), and there was sufficient blockage ( you really don't need much to cause a disagree)
The Blockage produce a differences in the pilots airspeed information.
The aircraft systems began to disengage as the data the computers use was becoming uncertain. (This is bread and butter avionics system behaviour)
The pilots took over manual flying and began trouble shooting

I have no problem with your speculation up to there. But:

...perhaps they forgot to fly it. (we have seen that time and time again)
The pilots got behind the aircraft and eventually lost control of the aircraft as systems continued to shut down.
The aircraft broke up after exiting the safe flying envelope and wandered past its structural design limits.

I think that part of the scenario is weak. The pilots "forgot" to fly and the plane "wandered" close to supersonic speeds? That is not as elegant a hypothesis to me as the pilots in an effort to handfly and trouble-shoot overstressed the rudder.

[Theoddkiwi]

The last bits of the scenario obviously are purely my own ramblings so i take complete ownership.

But my point is that, based on past events, somewhat controllable situations have got out of hand because the pilots have been either too slow or too preoccupied with the failures and getting to far behind the aircraft to be able to recover.

Like or not as much as we would like all pilots to be infellable, they like all humans make mistakes durign times of stress, trainings helps the vast majority of the time to minimise the mistakes. But on the very odd occasion some pilots like all human are unable to make the right decisions at the right time.

This not Pilot bashing, but i work with pilots day in and day out. I can tell you there are definately pilots i would rather be at the controls in a bad situation over others, most are fine, but some are just plane scary. This is the same with my own engineering mates, some are frankly better than others.

We all make mistakes, its just a matter of making the right mistakes at the right time as opposed to making the wrong mistakes at the wrong time.

Like it or not the Crew actions will play a big part in this accident.

[Gabriel]

The Vstab on its own explains the crash, but not when combined with the other evidence.

Eg Why did TCAS fail if the V Stab fell off, it has nothing to do with it.

Theod, your scenario looks good for me.

About the fin failing early during the events, ITS proposed that after loosing the fin the plane entered a severe Dutch roll. According to his scenario, the intense alternative sideslip angles and alternative side motion of the nose during the Dutch roll would have distorted the total air pressure sensed by the pitots and put some dynamic pressure on the static port which should read only static pressure. Due to the oscillatory motion and the fact that the pitots and static ports are placed on opposite sides of the fuselage, the variations in the pressures sensed by the pitots and static ports would be oscillating and of different sign between both sides. That would make altitude and speed readings erratic and different between systems, triggering the ADR disagree and all the sequence of system failures and shut down, just as if the pitots would have been blocked with ice.

About Occam's razor, the Dutch roll would be a direct and expectable consequence of the failure of the fin, so no additional assumptions there. What I don't know is if the total and static pressure errors during such Dutch roll would be really that large to trigger an ADR disagree. So for me by now that IS an additional assumption.

[Leightman]

Suppositions

Theo, I appreciate your measured reply and the background from which it comes. I don't think the vfin detachment was the initial accident cause either, as in: tail fell off, plane crashed. Blame may some day be laid on airspeed disagreements rendering the plane ultimately uncontrollable, but the pilots may have had enough intermittent info to maintain marginal control. There are still things about timing that don't add up. Timing acording to ACARS is about four minutes duration, beginning with instrument problems and ending with an assumption (?) that the cabin pressure alert referred to loss of pressurization and very serious problems. That meant the crew managed to fly the plane for four minutes, during which we have inklings, but no multiple message corroboration, that the vertical fin MIGHT have departed. So the vertical fin may not have departed until 0214 when ACARS information ends, or even later. ACARS may well not have able to keep up with all the messages it was asked to transmit. I haven't gotten a solid answer yet on how the message queue works for untransmitted messages. It does appear clear that the ACARS timestamp is of the alert occurance, not the time of transmission. Specifically, if ACARS got 15 alerts in the first minute, did the five it did not have time to transmit in the first minute get queued to the top of the list the second minute (and then bump out others), or did they get dumped for a new priority list? The heavy inference is that events occurred faster than ACARS could transmit. Still, cabin pressure loss still didn't come til 0214.
While an emergency descent might have been desirable as early as 0210, the pilots' need to control the plane with instrument conflicts AND manage speed and not allow attitude to go negative (or preferably to increase AOA RE the std procedure for unreliable airspeed) suggests that speed reduction trumped the desire to descend, that attitude may have actually increased and not much altitude is likely to have been lost in the first four minutes. At 0214 the plane is flying slower, but still high, and our info ends. At that point, the problem with the scenario of loss of control, overspeed, and airframe failure is the evidence of the galley, jump seat bulkhead, and victim injuries that are more consistent with a slower water impact. The only way I see to resolve this conflict is if the forward fuselage broke off, and the rest of the plane, wings and horiz stab largely intact, maple leafed or flat spun down. But the resulting impact would disagree with the forward impact nature of the latest victim injuries. I don't want to make too muich out of pjnk teeth, but hypoxia might not have been due to lack of oxygen (we've seen the mask pics) but rather too low an ambient pressure fot he 02 to be ingested. Especially if the descent rate was maple leaf slow. Yeah I know, lots of speculation here.

[Leightman]

Airspeed disagree

Theo's airspeed disagree due to icing may be most likely, but I cannot yet rule out violent lateral shear which could cause disagree and vstab damage (though on my last post I had those occuring at different times)

[P3_Super_Bee]

I am a Licenced Aircraft Maintenance Engineer, and i dont think the Vstab snapped off first causing the crash.

My experience is in the Avionics field, and have a pretty comprensive understanding of how the various sensors and electronics work, and how the failure of those sensors would affect many of the components within the aircraft systems.

In 20 years as a structural mech, the only thing structurally, tron chaser are good for is stripping screws. Just kidding.. LOL.

- The ACARS messages do not make any suggestion of a loss of the V Stab

Do we know we have every ACARS message generated? No. ACARS is not an FDR.

- The Fact that the aircraft structure is still attached to the V Stab does not support the mountings failing.

Not all of the structure is there only a portion. of it. Looking at the Vstab. There is structure pieces at the aft end of the vstab. There is the lower portion of the rudder broken off. It looks like the Vstab maybe came loose fro the forward end and tipped back as it came off the aircraft to the aft.

- Just because we have photos of an intact V Stab does not mean it fell of first. It fell off, that is all we can be sure of, but when is any bodies guess.

I agree.


Playing a little devil's advocate here...

[Theoddkiwi]

In 20 years as a structural mech, the only thing structurally the only thing a tron chasers are good for is stripping screws. Just kidding.. LOL.

Have you been talking to mechanics i work with? I catagoricaly deny having any involvement in the stripping of screw heads.

The 737 Logo light panel on the lower surface of the hori stab has two screw in the corners of the panel which have a thicker shank than the rest of the screws. Some clowns tighten these ones up so much that i probably have an issue getting them undone once every other month. Of course i get all the blame.

The bane of my existance

I have no probs with the devil and his jolly advocates