Possible cause of AA flight 587 crash...a new thought

Vanity | 11/15/01 | Agent Smith

[EggsAckley]

Sabotage is certainly a possibility, but the list of suspects would be pretty short. These facilities operate 24/7 and the chances of an outsider entering and accomplishing this task unnoticed are remote.

I'm not so sure about this statement. An American Airline pilot friend of mine says that security is extremely lax on the ground, in areas where the public is not allowed. He has always been nervous about baggage handlers, mechanics, etc. due to the fact that they seem to be able to go wherevere they please, unrestricted.

[surfer]

in a cessna 172 the wake of a hot air balloon would toss you around...the wind shears and cross winds in New England are always strong as well...

[Fred Mertz]

Someone told me an F-16 took it down!

[Blueflag]

I agree. I recall the winds were out of the S- SW that day (thus the departure runway chosen). Also, the smoke from the fire was moving pretty rapidly ~100 - 300' AGL from west to east (generally). One could presume the winds aloft to maybe 800 - 900 feet were roughly the same, so the wake from the heavy should have progressed east as well. I have not seem the paths and times of the two aircraft, so this could be all wet. BUT ... It could be the A300 was inadvertently flown right into the WT of the '47, even though it turned short of its path (reportedly?).

[Agent Smith]

I agree with you. Sabotage is a very unlikey possibility. I am sorry if my post did not make this clear enough.

[1L]

Wake turbulence is left behind an aircraft

Would someone explain to me the physics behind wake turbulence? I can't understand how there could still be turbulence and jet wash from a plane that has left that immediate airspace 45 seconds ago -- even with no wind.

[MassLengthTime]

Re the delamination:

Meanwhile, in Tulsa, the maintenance records group discovered that one of the six main attachments that held the Flight 587 plane's tail to the fuselage underwent a significant repair in 1988, soon after the plane rolled off the assembly line but before it was delivered to American.

The left-center fitting "delaminated," and technicians in Toulouse, France, where the plane was built, added a "doubler" and rivets to reinforce the joint, Black said at the evening briefing. Airbus then delivered the plane to American but did not indicate that special inspections of the repaired area were necessary.

The attachments are to be checked every five years, Black said. The last check of the American A300-600's tail/fuselage attachment fittings took place in December, 1999, which is also when the plane had its last heavy maintenance visit.

So the last inspection of the 13 year-old repair was 2 years ago. How much experience is there with assessing incipient failures with this kind of repair? How did they pick a five year inspection interval?

[Blueflag]

Zordas--

"However, that also should have produced a prominent heading change, as a first event."

Absolutley-- matching the FDR data to the radar tracks will be crucial to making this theory plausible. If the aircaft were suddenly pitched/yawed/rolled, whatever, absent input from the flight deck, then we can legitimatley yell 'wake turbulence'. It is telling that the crew did just that-- they ID'd the behavior of the aircraft as wake turbulence.

Supposing we are right, the issues (to me) remain -- why did the VS fail, and why are A300s not grounded right now if they cannot, even in one instance, survive CAT/WT?

To American's credit, I believe THEY have grounded all A300s subject to sucessful inspection of the VS assembly.

[KirklandJunction]

LOL!
172's here in Arizona, especially summertime, I've often felt like the proverbial one tennis shoe in a commercial clothes drier, wishing my stomach was at sea level far far away.
...but nothing broke.
CAT can be a bitch.

[Blueflag]

I was agreeing with you already! No worries. Your post was clear, mine was not. An earlier poster had cried 'sabotuer!, not you.

[rogers21774]

What are your credentials? Do you have any specific expertise in the area of airline crashes?

[Pumba]

Clearly sabotage???? Have you ever seen aircraft parts up close? What is your basis for that allegation? Do you suspect that someone climbed up on the horizontal stab, accesed the vertical stab, somehow delaminated the composite with a heat gun or hammer unnoticed while the aircraft was in the hangar? or mabey it was the people in black helicopters that hovered over the airport, rappeled down and sabotaged the vert. stab.

Best bet is you are wrong, as an A&P mechanic, I HAVE seen delamination, and I KNOW what it takes to delaminate carbon fiber. It isn't easy. Also, in the area under discussion, it is almost impossible to discover delamination withought removing all of the access covers. This is normally done at a 'D' check which occours on a hours/cycles (landings) basis. If there has never been a problem with that area before it doesn't need to be specially checked again. After this incident, I am positive the area will be checked just like when all of the DC-9/ MD-80 series aircraft jackscrews were checked after the Alaska Airlines incident in California. Lets keep our heads on here people.

Yes, I concede the NTSB and FAA are torn between the airlines and safety but, let them do their job and keep your uninformed opinions to yourself.

[Pharmboy]

The assembly did not fail. Bolts still in place. My guess would be someone took a rasp to the stabilizer.

[Gadsden1st]

tossed around like a rag doll.
Did the tail of your aircraft fall off as a result? I have been in the wake of a large tug in a small (27') sail boat. My rudder didn't fall off, mast didn't fall. I don't recommend it as safe practice. In a narrow channel may get pushed off course and run aground. I do expect vessel to stay in one piece. I sure don't like the idea of flying if parts fall off encountering what I consider normal "extreme" conditions.

[Daffy]

How do you account for the large piece of wing retrieved from the bay? It would seem to me the wing piece knocked off the tail. (the photo shows a very large piece)

[Blueflag]

OK, just like boats leave a visible wake in the water, that is dependent upon speed, draft, angle of attack, shape of hull, etc., AND just like there is a very definitive edge to the wake, AND just like water waves of a wake are actually circular in motion (if you studied the physics of a standing wave in water)-- the same is true for airplanes--

A big heavy airplane, like a 747, moving through the air, has to produce a lot of thrust and lift to fly, so it has to move a lot of air from where it was to where it need to be to generate lift. In doing so, as the air encounters the slightly swept wing, flows over it, and then off the trailing edge, the overall mass effect of the air is that it forms highspeed whirlpools of air at the wing tips. These are analogous to the wake of a boat that you can see. Now, there is also disturbed air behind an aircraft that acts like the propwash area behind a large ship. Both the 'propwash' and the 'whirlpools' generate turbulence.

The whirlpools of spinning air exist for a while as part of the standing wave (the wake) generated by the aircraft. If the wake turbulence was visible to the eys (it is sometimes when you land on a moist air day-- as a streamer) you would see a corksrew of air behind the plane. The contrail of a high altitude jet is more indicative of the 'prop wash' than the whirlpool.

Hope that helped.