Tbird
Topic Author
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Wake Turbulence Cause Of AA587

Thu Nov 15, 2001 6:08 am

Greetings:

More and more news agencies are reporting that wake turbulence may have been the cause of AA587's crash. CNN reported that a JAL 744 was only 90 sec's ahead of AA587 which is to close. I could see wake turbulence affecting a smaller jet but an A300 is rather large to be affected that much by a 744's wake. A few years ago NASA tested the wake turbulence theory in a USair crash where they flew two 737 less then a mile from each other and nothing major happened. What does everybody think of this theory?

Thanx
Tom
 
ryu2
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RE: Wake Turbulence Cause Of AA587

Thu Nov 15, 2001 6:12 am

There was a rattling sound heard over the CVR or so reports say.

But what if the wake turbulance somehow induced vibrations in the airframe at the critical resonance frequency, thus causing the vibratings to increase rapidly, leading to structural failure?

Has this fundamental physical phenomenon ever led to a airplane crash before, I wonder?
 
777236ER
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RE: Wake Turbulence Cause Of AA587

Thu Nov 15, 2001 6:13 am

Firstly, a question mark in front of the topic title?

Secondly, wake turbulance can be a big problem, usually though an A300 wouldn't be severly effected by even the greatest 747 wake turbulence/vortex. Lol, they'll be those who say the Wake Turbulance is the last resort of the NTSB. A 737 rudder hard-overs was blamed for a LONG time on wake vorticies.....
Your bone's got a little machine
 
chepos
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RE: Wake Turbulence Cause Of AA587

Thu Nov 15, 2001 6:16 am

I think its better for people to stop speculating. I've heard so many things righht now from bird ingestion to a possible bomb. The media speculating and the people repeating this is making people not wanting to fly anymore.
Chepos
Fly the Flag!!!!
 
777236ER
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RE: Wake Turbulence Cause Of AA587

Thu Nov 15, 2001 6:18 am

The rattling could be a stickshaker. Remember that. And yeah, Chepos, no more speculating people please.

Yeah, yeah, i'm aware of the irony of that, considering the start of my post  Smile
Your bone's got a little machine
 
flysab
Posts: 102
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RE: Wake Turbulence Cause Of AA587

Thu Nov 15, 2001 6:27 am

Wake turbulence appears only from the point of rotation of the aircraft and stays under the flight path.
As the A300 rotated for sure (except if it took off from an intersection, but then you normally have to wait 3 minutes to start the take off roll behind a heavy) farther from the end of the runway than the 747, and then climbed with a better rate, the wake turbulence theory is probably not funded.
 
Red Panda
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RE: Wake Turbulence Cause Of AA587

Thu Nov 15, 2001 6:33 am

I doubt. If it was a small prop, then I would believe wake turbulence is the cause. But, here, pple, it's A300, which is a wide-body and heavy. Can it be so easily affected? I doubt.

Is NTSB hiding the real cause by throwing out this theory?

I guess so.
r panda

Sorry, NTSB, and those working hard in the investigation.
 
heavymetal
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RE: Wake Turbulence Cause Of AA587

Thu Nov 15, 2001 6:36 am

Speculate away. The NTSB is doing the same thing we are. Rule nothing in. Rule nothing out.

Speculation means theory and theory gets proven into fact and fact is what fixes things.
 
777236ER
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RE: Wake Turbulence Cause Of AA587

Thu Nov 15, 2001 6:38 am

Red Panda, it didn't say the NTSB were covering this up. I merely noted that somepeople may start churning out the conspiracy theories after ther wake-turbulance comment.
Your bone's got a little machine
 
AWspicious
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RE: Wake Turbulence Cause Of AA587

Thu Nov 15, 2001 6:53 am

I'm wouldn't be surprised if these pages are being monitored.... in light of recent developments. However, I gotta frown about the wake turbulence 'query'. The plane apparently only achieved an altitude of 2800 ft. Could it break apart so much and so soon? Would wake turbulence cause an A300 to break apart in the air? I'm of the assumption if the plane was to experience abnormal dynamic forces at a much higher altitude - say, the 13000 587 was cleared for - I could see there being enough time for the aircraft to become over stressed and break apart. Or, if it was wake turbulence at the suggested 2800 ft. she'd just loose it and fall to the ground.... intact till impact.
I wonder if perhaps the harmonics heard wasn't the tail section coming apart.... or, the initial cause of the tail section seperating.
Look, I don't think anyone is saying this or that IS what happened. all we're doing is wondering if this or that could possibly be a cause/contributing factor. Perhaps, some of us might learn something from these posts, no?
Nevermind political correctness - Envision using your turn signals!
 
VirginFlyer
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RE: Wake Turbulence Cause Of AA587

Thu Nov 15, 2001 7:03 am

I think the wake turbulence is credible, for exactly the reason you said: if it was wake turbulence at the suggested 2800 ft. she'd just loose it and fall to the ground.... intact till impact

The aircraft did come down intact, other than the vertical stabiliser and the engines. As said on other posts, if the vert stab somehow came off, the wake turbulence could have caused a side slip, which would have torn off the engines, and resulted in the rest of the aircraft coming down in one place. Which is pretty much what the debris field indicates.

The wake turbulence is definitely a factor. Whether it caused the vert stab to come off or not is unknown, but once the vert stab was gone, wake turbulence, or indeed any unsettled air, would have led to the crash.

V/F
"So powerful is the light of unity that it can illuminate the whole earth." - Bahá'u'lláh
 
AirT85
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RE: Wake Turbulence Cause Of AA587

Thu Nov 15, 2001 7:32 am

MSNBC reported that this airplane had an encounter with wake turbulence in 1994. Although the guy said the plane would have been inspected, which im sure it has been, could a second encounter possibly weaken the planes resistance to the vibration of encountering the wake? Im not trying to add to speculation, just asking a question.
Tony
Why would God make us all so different, if He wanted us to be the same?
 
Red Panda
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RE: Wake Turbulence Cause Of AA587

Thu Nov 15, 2001 7:44 am

I don't know whether NTSB is covering up some inside stories or not, but I am quite disappointed in their investigation of TWA800.

Will NTSB ever find the true cause(s) of the accident?
also, will the public be informed about the true cause(s)?

I just have too much question marks and disappointment in my head.

r panda
 
Guest

RE: Wake Turbulence Cause Of AA587

Thu Nov 15, 2001 7:57 am

I don't buy the wake turbulence story either... remember also that wake-turbulence descends at a rate of 200ft a minute I beleive... The JAL 747 must have taken off at a later point on the runway as the A-300 did... it had aslower rate of climb and subtract 300ft. for the 90 second time span. So unless the A-300 had a poor (which the A-300 doesn't) or restricted rate of climb, it seems very unlikely that it should have flown into the wake of the 747. Furthermore, and as stated before the A-300 must have been quite close to the 170,000kg. mark. To shake this heavy Airbus around and cause it to crash??? Very far fetched theory if you ask me...

Vibrations can mean many things such as an imminent stall or engine failure...

In the twin engine airplane I'm getting my multi rating in right now (Piper Aztec) if you are in a nose up attitude (climbing) and the critical engine fails and the pilots don't recognize or take appropriate action the plane will turn upside down and start an unrecoverable nose dive within seconds. Don't know if this is true in the A-300 however.

In my opinion, a plane that looses it's rudder will not go down nose first!!!

Don't know if this is true with the A-300 however...
 
crank
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RE: Wake Turbulence Cause Of AA587

Thu Nov 15, 2001 9:33 am

I dont know what a 744's turbuence could do on an A300, but I've experienced wake turbulence on a DC-9 this summer. It was about 90 seconds after takeoff, we entered turbulence for about 20 seconds and after it was gone. An Azores A310 had taken off about 2 or 3 minutes before us so I guess that's why.

Though, I hardly doubt this could cause an airplane to crash
 
flightsimfreak
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RE: Wake Turbulence Cause Of AA587

Thu Nov 15, 2001 10:27 am

In the AIM, Paragraph 7-3-2, it says "In rare instances a wake encounter could cause inflight structural damage of catastrophic proportions." Now, I'de have to agree that the A300 would be in the air long before that 747, and would be climbing much faster then him, so this is unlikely. But, if ATC had put a restriction on his climb for trafic or other reasons, he could have easily flown through that 747's wake.
 
che
Posts: 516
Joined: Wed Feb 09, 2000 10:02 am

RE: Wake Turbulence Cause Of AA587

Thu Nov 15, 2001 10:58 am

A theory and just that. But its does need to be throughly invetigated. Any lead at this point should be followed up and investigated. Now is the time for the "I think this might have happend but why and how" and also the "this might of happend because of that" type of queations.

As for the wake turbulance theory. I think it should be checked out. The A300 is rather beefy and I don't see how a 747's wake could really affect an A300 too severely. But then again I could be wrong.

che
 
PANYNJ
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Joined: Fri Sep 21, 2001 5:03 am

RE: Wake Turbulence Cause Of AA587

Thu Nov 15, 2001 11:05 am

THE VERTICAL STABILIZER SEPARATED FROM THE AIRFRAME!

This hasn't happened in like 50 years.
 
tygue
Posts: 220
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RE: Wake Turbulence Cause Of AA587

Thu Nov 15, 2001 11:46 am

Compressor Stall? Failure and injestion of an N1 blade?


Just wondering aloud...
 
tygue
Posts: 220
Joined: Sun Jul 18, 1999 4:42 pm

RE: Wake Turbulence Cause Of AA587

Thu Nov 15, 2001 11:52 am

Also, we can pretty much credit the crash itself with the loss of differential power compounded with no control over yaw, seeing as the number one engine and vertical stabilizer were both found over a mile from the main impact site. The aircraft should've been nearly impossible to control without two engines or a rudder.

What caused either of these events is beyond all of us.

However... aircraft engines are designed to fly up over the wing and fall to the ground SHOULD a seperation occur... this is what happened in the AA Flt 191 incident in 1979. The engine lifted and flew back as it should have, but struck the leading edge slats on it's way off which causes the slat disagreement. Perhaps something not unlike Flt191 occured in this case.

Although, had the engine hit the tail on the way off... would it not have as well been found in Jamaica Bay?

Again... just thinking out loud.
 
seagull
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RE: Wake Turbulence Cause Of AA587

Thu Nov 15, 2001 11:57 am

NTSB never said that wake was the cause, only that the crew mentioned it in conversation. TWA 800 was not a coverup, NTSB did a pretty good job with that.
 
tygue
Posts: 220
Joined: Sun Jul 18, 1999 4:42 pm

RE: Wake Turbulence Cause Of AA587

Thu Nov 15, 2001 12:02 pm

I'm getting quite a kick out of the TWA800 comments.

Have you any idea how difficult it would be to determine the cause of a crash that left absolutely no clear clues?
 
delta-flyer
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RE: Wake Turbulence Cause Of AA587

Thu Nov 15, 2001 12:04 pm

Try reading a source that is a little more credible, such as AW&ST. Here is a link to the AA587 acident:

http://www.aviationnow.com/avnow/spSec/aaqueens.jsp

Pete
"In God we trust, everyone else bring data"
 
Guest

RE: Wake Turbulence Cause Of AA587

Thu Nov 15, 2001 1:08 pm

is wake turbulence like when a plane is by you and you get turbulence from it? when we were on the ground in mpls, i was going back to rochester and i was in an RJ-85(avro) and like a DC-9 or like a 727 was ahead of us and the plane was shaking, it was annoying
 
spacecadet
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RE: Wake Turbulence Cause Of AA587

Thu Nov 15, 2001 4:47 pm

Red Panda: Have you actually read the TWA 800 accident report?
I'm tired of being a wanna-be league bowler. I wanna be a league bowler!
 
lehpron
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RE: Wake Turbulence Cause Of AA587

Thu Nov 15, 2001 5:28 pm

A few years ago NASA tested the wake turbulence theory in a USair crash where they flew two 737 less then a mile from each other and nothing major happened.

Actually NASA tested the 737 behind a 727, slightly larger, but not each other and certainly not a 747. Not that you've implied or suggested. IMO, wake drag is a funny force, in rare cases, size might not matter at all.
The meaning of life is curiosity; we were put on this planet to explore opportunities.
 
N400QX
Posts: 1981
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RE: Wake Turbulence Cause Of AA587

Thu Nov 15, 2001 5:41 pm

Damn, I was really hoping to post some relevant information here, but thanks to Bove this thread will probably be deleted. Oh well, I'll try anyway--

First, I don't exactly like the topic-- its misleading. It is WAY too early in the investigation to make comments like that.

Second,

>CNN reported that a JAL 744 was only 90 sec's ahead of AA587 which is to close

Well, I heard otherwise. The last I heard from the media was 9 minutes. Thats quite a difference. And the media isn't always right.

I really doubt wake turbulence was the cause of this crash. It isn't to be ruled out, I just don't think it was the cause-- its just unprecedented. I have found the media is jumping around in their conclusions even more and worse than a 'regular' incident, which is irresponsible.

Let's just wait to see what the NTSB says? Although, my confidence in them isn't total-- that NTSB woman at the press conference said (this is the day of the crash) that terrorism was not the cause. It may not be, but the same day isn't the day to be making nearly unfounded claims. Ugh... we'll just have to sit tight.
 
IHadAPheo
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RE: Wake Turbulence Cause Of AA587

Thu Nov 15, 2001 6:04 pm

N400QX, hopefully the powers that be are wise enough to only delete the post with the vile photos (I wonder if Bove understands that the photos are copywrited material) and not the fine post in which it is sadly posted. (I hope this made some sense)
Pray hard but pray with care For the tears that you are crying now Are just your answered prayers
 
CV990
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RE: Wake Turbulence Cause Of AA587

Thu Nov 15, 2001 6:54 pm


Hi!

This accident reminds me another one that happened some almost 40 years ago in Japan, this time it was a B. 707-436 from BOAC - G-APFE - that passed very close to Mount Fuji and the winds - called rotor winds - just smashed the tail of the Boeing, then all the engines where pulled by enourmous g forces and the plane crashed almost in flat configuration, also we have some cases that the wake turbulence generated by bigger airlines have donne disastrous effects in airplanes, first of them was in Dallas when a Delta DC-9 crashed because the minimum separation between that plane and the America DC-10 was not corrected, so for me the conjunctions of the wake turbulance and eventually some windy conditions lead to the A300 from American to crash, unfortunetly even today and with the crews beeing aware of the effects we still see inocent people beeing sacrificed, I'm sure if the American Airbus delayed 1 or 2 more minutes the take-off perhaps we wouldn't be here talking abaout this tragedy. Finnally as we know the plane was delayed, so also the crew was also stressed and wanted the best way they could to recover that delay taking off as soon as possible.
Regards
CV990, the Maserati of the skies!

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