T-Storms Blamed For Jet Crash

[Chris Carter]

Some experienced pilots are saying that no pilot would dare attempt to punch through a thunderstorm of any kind, but some of them try to fly around the tops and sometimes can get caught in a updraft, this may have happened as i read somewhere that there was estimated 100mph winds within the storms.

 

[cdcollura]

Good day all,

Updraft speeds in a "hot tower", defined as any deep tropical thunderstorm which involves convection from the low level (boundary layer) up to and even exceeding the tropopause (50,000 - 60,000 feet). This is common with tropical cyclones as well.

Updrafts in these storms are anywhere from 50 to 100 MPH. In comparison, a supercell storm can have updrafts exceeding 150 MPH! With that, these updrafts are also "bounded" next to strong downdrafts as well, that means, if a plane is caught in a 80 MPH updraft, then suddenly flies out of it into a 80 MPH downdraft, the "shear" experienced by the plane is 160 MPH ... Loads induced SHOULD tear any non-fighter-jet type plane apart.

No commercial aircraft

 

[Anthony Petito]

http://www.time.com/time/world/article/0,8599,1902421,00.html

Found a Time article that references past findings on A330 and A340 models having issues with Air Data Inertial Reference Units (ADIRUs) and how the flight computer interprets/responds to data presented to it by these units. A330/340s have 3 of these units on board that help feed data into the flight computer. These units esentially feed the computer the data needed to keep the plane flying when autopilot is initiated. The flight computer algoithm is designed to gather data from all 3 units, however, it was also designed to throw out what it would consider "bad" data from one of the units. Instead, relying one the other 2 for accurate flight data.

It seems in past instances, the flight computer instead did the opposite by listening only to the ADIRU that was feeding bad data in the flight computer; which, in turn, caused the computer to immediately dive the plane. I'm not an expert, but in the instance references by Time, the flight computer responded to an ADIRU unit that reported lack of air over the wings, or measuring it's angle of attack (AOA). The response for such an event would be to dive so the plane doesn't stall.

After reading Tim's analysis, I would be intereted to see what would happen if the plane, flying at ~FL350 suddently dived below FL200 or lower. Depending on how deep the dive is, would there have been time for a mayday call? Would ice become a factor? Could the developing storms have produced enough shear to rip a plane apart?

I'm sure the weather played a pretty significant role in the crash, but my guess is that other events are at play here and the weather didn't do anyone a favor.

 

[Ryan Moats]

Well, through past events, being a pilot my self, i'm gonna suspect electrical fire
since fire seems to be the only thing in many past crashes to have slowly/quickly take out many electrical systems and overwhelm the plane.

The Swiss air flight, Valu JEt, etc which all went down because of a fire which slowly took out all electrical systems then flight controls and overwhelmed the plane.

Turblence, HAHAHA, no way did that take down the plane and especially nor did lighting. Check up the the 747 Evergreen jet that took off from alaska.

Almost every plane is struck by lighting and trust me, planes are DESIGNED to not be effected by lighting. Half the time, a plane gets hit and they crew doesn't even know it.
There are too many safegurads and redudant systems for just simply lighting to take out a highly advance jet liner.

My theory, Turbulence knocked around something causing whatever to start a fire. The fire slowly burned through the electrical system taking maybe the radios, avionics whatever first and slowly burning through the rest of the vital electrical systems which in turn power the flight control systems which and caused the plane to be doomed.

This would explain the messages being sent out before the messages stopped about electrical system failure. As the fire burned, it didn't burn the instrument wires to the device that monitors the electrical systems until the fire burned through the electrical part of that device.

A fire slowly kills power to each system on by one until overwhelming the plane. It could of take out the radios first or the Mayday never came from the pilots because where they where in the ocean, might of been no radio coverage. Hard to say.

We shall see over the next few weeks.

 

[Clarence Bennett]

Anyone see the Piece Dr. Forbes did on TWC? Was pretty basic and brief, but it seems to have shot the theory of lightning or updraft/downdraft all to you know what. Made sense to me. If they ever find the boxes, there is going to be alot more to this story I believe.

 

[Jay McCoy]

It depends on who you believe expert wise as to whether the plane broke apart or not. I dont buy a fire or lightning strike. New aircraft like this have very good fire suppresion systems and a lightning strike wouldnt cause loss of cabin pressure.

According to actual air safety experts and people from the airlines that messages sent from the plane indicate the plane was breaking apart in flight due to violent storms which jives with Tims great analysis.

http://www.foxnews.com/story/0,2933,525043,00.html?test=latestnews

If you read a report using Brazil's 'defense minister' the oil slick being in one place means the plane didnt break up. I dont give alot of credbility to a defense expert over people who actually fly or designed this aircraft or are aviation experts. Also the fact that automated messages indicated loss of cabin pressure and 2 seperate debris fields have been found so far indicating to me the plane breaking apart. If it came down in 1 piece then why 2 seperate fields?? Its amazing how the media can come to a conclusion using 1 "officials" comment when he isnt even in the aviation field.

http://www.cnn.com/2009/WORLD/americas/06/03/france.plane.memorial/index.html

 

[Anthony Petito]

If you read a report using Brazil's 'defense minister' the oil slick being in one place means the plane didnt break up.

I guess it depends on what they found in the debris field with the oil slick. Most of the fuel is stored in the wings and a center fuel tank that site between the wings in the lower hull of the aircraft. There's also a smaller tank in the tail section as well.

It could be that's where that the oil click they've found is where the either the tail or center/wings area of the plane fell.

The problem is that both Brazil and France are releasing conflicting reports. 1 says there will be no survivors while the other is holding hope, one says the plane was struck by lightning, the other says severe turbulence and no conflicting reports about what they're finding. It doesn't help matters when the US Media picks and chooses things to report and runs with it.

*sigh*

 

[Jay Bell]

Alright....

I'll chime in here. Having been a professional pilot of over 15 years ( read commercial/airline) and having flown over 21 years now, I can dispute the lightning myth completely. I have been struck in commercial aircraft over a dozen times....and NEVER lost anything that was critical to safe flight. Lightning does not "fry" entire electrical systems, or cause loss of pressurization, or any of the other issues reported to have occurred on the A330. What it does do is this...It creates structural "burn" damage. What i mean is this...there is, in general an entrance point and an exit point. These areas CAN create weak spots in aircraft skin (whether aluminum or composite) as well as can do damage to an individual component that is not properly grounded to the airframe ground. In fact, most times you don't even know you were hit until a maintenance inspection sometime later.

I don't like making conclusions or assumptions about an accident until all the facts are in. There is usually not one single "smoking gun". It is always a chain of events.

Let me give a scenario. Assume this aircraft was flying in the region of adverse weather at an altitude of, say 35,000 to 37,000 feet. This would be normal for this aircraft. Many have made the assumption that pilots fly around the worst thunderstorms (I read a few posts back "above level 3"). This is a very true statement. However, there is a problem with this in that airborne weather radars do NOT work well above 30,000 feet. Why? Quite simply because precipitation is frozen above this level. When the radar is tilted towards the surface, it paints only the precipitation core (and nearer the surface) but NOT the updraft region...which most likely is not the same area at that altitude. Now, if you are flying at 37,000 feet and in the clouds, you may not be able to visually "see" a 50,000 foot TRW. So, unless the radar is tilted far enough down to paint the lower core areas, it may never be seen until too late.

I have, in the past, inadvertently entered weather I wished I had not. Having said that...I could see how this accident "might" have transpired.

The idea has been implied that this aircraft was somehow "weaker" because it was made of composite materials. Truth be told, composite aircraft are somewhat stronger than aluminum framed aircraft. The A330 incidentally is only composite on the skin, and has an aluminum frame.

In any event, if indeed it was a thunderstorm encounter, supercell, or not, a storm that reaches 50,000 feet WILL bring down an airliner. It has happened before, will happen again, and "might" have happened in this event. Airliners are approved to FAR 25 standards which essentially design the aircraft for an operational limit of 2.5 g's and a maximum somewhere around 4g's (I believe). Military aircraft have experienced upwards of 8-10 g's in the updraft region of a thunderstorm. So, based on this, you can see even an airliner is no match for ma nature.

Jay

 

[cdcollura]

Good day all,

Excellent post, Jay ... And quite interesting.

The radar is misleading as "hydrometeor" sizes are also smaller, and ice crystals present very poor returns on radar displays. The SPEED of the air, however, moving up /down is a problem, and not necessarily reflected on what the radar "sees" at that height. A level 3 (from 1 to 6 VIP) storm at 35,000 feet is ALOT, and the question is what "level" will that same storm be just above MSL?

Second, I beleive all general aviation aircraft have a MAXIMUM load of 3.8 G's (4.3 for utility).

These G limits are way below the G forces a thunderstorm core encounter will present = Possible catastrophic failure.

 

[Chris Carter]

Hey, just a quick question here, werent they flying at night?

 

[Anthony Petito]

Hey, just a quick question here, werent they flying at night?

Yes, I believe it was about midnight local time in the area where they crashed.

 

[Jeff Russell]

Be careful when stating G load limits. Most limits are for safe flight. Limits experienced beyond those does not mean a failure will occur. Aircraft manufactures do jig test on test beds to determine actual loads were failure will occur. Search youtube and I'm sure you can find a video of this procedure. You will be amazed by how far the wings can bend upward before failure!

Jeff

 

[Jarrod Cook]

Interesting scenarios and commentary here. However, I think more focus should be placed on the in-flight depressurization. Sounds like it broke up one way or another structurally. They seem to want to rule out an explosion too due to so much fuel and oil found on the ocean surface. The fire theory sounded good, but would this cause rapid depressurization?

Unless they find the data recorders, we may never know truly what happened. I'm surprised so many underwater searches have taken place and *now* they are finally interested in designing floating "black" boxes.

 

[MClarkson]

I would think it is *possible* that an extraordinarily strong bolt of lightning managed to take out all or enough of the electronics that control the plane.

Of course it is possible that turbulence damaged the plane enough to doom it, perhaps in combination with improper crew response when entering turbulence.

While you probably wont find a pilot charging into the core of strong storm very often(although it happens by accident sometimes), you will find airliners routinely flying through the fringes or very close... Usually you can get away with it.

 

[Greg Campbell]

Today's big news is the recovery of the intact vertical stabilizer. It appears to have been sheared off at the base. Does anyone know if the victims were found in the same vicinity? If not, it's sure tempting to imagine that the tail broke off, causing the depressurization warning and subsequent crash. (I know this is an unjustified leap.)