Vic,
Yes, indeed. The plot thickens. I applaud you
for applying your brain and persistence to this
incident!
Given the facts of the transcript and timeline,
there clearly must be another precipitating cause.
But I don't think you need a rocket scientist to
make that conclusion!
But, if you want one, I am here! "I confidently
say that your analysis is sound and deserving of
serious attention. It sheds new light on the
reported facts, and raises questions about the
validity and direction of the current investigation."
The vertical tail assembly of an aircraft, moving in excess
of 200 miles an
hour, is not designed to survive the aerodynamic forces that would
occur if
a plane were to rotate in a flat spin that reached 90 degrees.
Wind
resistance would blow off the vertical tail assembly in a way
not unlike a
child would blow out a candle on a birthday cake. The broken off
tail
assembly, found so far away from the crash site, indicates that
the flat
spin occurred close to the time when the pilot first lost control
of the
aircraft.
Confirmation of the flat spin should be evident by closely
examining the
flight data recorder altimeter readings. The construction of the
outside
altimeter sensor, located on the side of the aircraft, would make
the
altimeter artificially react to a flat spin. The forward momentum
of the
aircraft would subject the altimeter sensor to an overpressure
reading when
the sensor faced the direction of the plane's forward movement.
An
under-pressure reading would occur when the sensor faced away
from the
plane's forward movement.
Now what could cause the aircraft to snap into a flat spin?
The only thing
I can imagine would be the deployment of an engine reverse-thrust
cowling.
But if that happened, the flight data recorder would indicate
the
corresponding pressure measurements from the engine pressure sensors.
But imputing all of this from just a picture is just a wild
guess. We put
flight data recorders on our aircraft to eliminate the need for
guessing.
What does it say?
In a press conference the NTSB has proposed that pilot inputs
tore the
rudder and vertical stabilizer off AA 587. This is their tentative
scenario:
1. AA 587 encounters wake turbulence generated by the JAL 747
five miles
ahead.
2. The AA aircraft is sufficiently disturbed that the pilot takes
extreme
corrective action.
3. This takes the form of applying full left rudder, causing the
airplane to
go into a sideslip. He holds the rudder until the sideslip reaches
maximum,
which is about 10 degrees, equal to the maximum rudder deflection
at this
airspeed. When the sideslip is established at this maximum, the
pilot
suddenly applies full right rudder.
4. Although heretofore unknown, this combination of rudder movements
is
sufficient to stress the vertical fin beyond its design limits.
This
analysis was published in the January 21, 2002 issue of Aviation
Week & space
Technology, and is cited by the NTSB.
5. Implied but not stated by the NTSB is that the loss of the
tail fin
caused the crash.
I have the following comments. A series of improbable events
occurred,
if the NTSB scenario is correct. First, pilots routinely fly through
wake
turbulence. It is rare to take off or land without following another
aircraft, because the airports are so busy. The effect of wake
turbulence on
a large transport category aircraft like the A300 is nothing more
than
momentary turbulence. But in this case the turbulence must have
been
extraordinary (highly improbable but not impossible). We know
it was
extraordinarily severe because the pilot took extraordinary steps
to control
the aircraft. That is, this is the necessary initializing event
for the NTSB
scenario.
Second, the use of rudder to control the airplane is most unusual.
The
wing tip vortices produce a rolling motion in the air mass, and
thus a series
of rolling forces on the wings and fuselage. This is clearly distinguishable
from a force causing a yaw. To the extent that much control movement
is
required for such an encounter, it is aileron movement and possibly
some
elevator movement.
Third, even if rudder was applied, the use of extreme "to
the stop"
rudder is inexplicable. When the airplane had achieved a ten-degree
sideslip, moving it back to balanced flight could have and should
have been
done by simply (and gently) releasing the rudder force. But the
NTSB
scenario requires that the pilot quickly reversed the rudder input,
forcing
the opposite (right) pedal all the way and holding it there. Simply
put, I
can't imagine a situation where a pilot would do this, other than
possibly on
an engineering test flight for initial certification. Air carrier
pilots
constantly practice being as "smooth" as possible, mainly
in order to
maximize passenger comfort. But it is also a sign of professionalism
and
individual pride.
Fourth, it is far from clear why the loss of the tail fin caused
the
crash. The fin weighs much, and has a long moment arm to the center
of
gravity of the airplane. So we could expect the nose to drop when
the tail
departed. Would the elevator and movable stabilizer have enough
authority
to hold the airplane level? This is, I suspect, not a difficult
question to
answer, but apparently it has not been addressed. In other words,
just
because the fin fell off it does not automatically follow that
the airplane
should crash. We need more on this from the NTSB.
I need to remind this group that the fire and the engine being
slung off
are not in the "official" record. Nor is it likely these
two items will ever
appear as "facts." They derive from witness testimony,
and at the earliest
stages of the NTSB investigation the witness testimony was trivialized.
Whether the engine could have been slung off due to the side
loads on the
pylon caused by the alleged extreme rudder inputs is another issue
that
should be amenable to engineering analysis. But this won't be
done simply
because the engine never fell off, you see.
The Aviation Week article should be studied with care by all
in this
group. I don't think it was "faked" in any way. And
I am now quite sure the
NTSB will use it as the "probable cause" of the accident.
On the other hand, I expect Airbus Industrie to raise hell,
and probably
to counter the Aviation Week analysis. For example, it may be
that the
actual proprietary design load limit exceeds the failure point
found in the
Av Week article. There is a hint that this is the case with Boeing's
rudder-vertical stabilizer systems.
Another party that will be heard from is the Allied Pilots
Association,
which is the pilots' union at American Airlines. They may be joined
by the
Air Line Pilots Association, which has a formidable engineering/accident
investigation cadre. This is because, regardless of how it is
glossed, the
NTSB scenario bottom-lines at pilot error. And in a sense the
worst kind of
pilot error, in that the maneuvers allegedly performed are such
that they
would be surprising if done by a candidate for a private pilot's
license.
Finally, it seems to me that the voice recorder should tell
us if
anything like the NTSB scenario was underway. The missing last
ten seconds
are unfortunate, but the extreme wake turbulence followed by extreme
pilot-induced yaws must have occurred prior to CVR cutoff, and
would almost
certainly have resulted in comments from both pilots. Or so 31
years in the
cockpit tells me.
--Bob Durant
I was at the crash scene the day this crash occurred.The vertical
fin was
extracted from the bay completely in tact. The rudder surface
was not
attached to the fin.This demonstrates RUDDER FAILURE.If this were
vertical
fin failure, segments of the rudder would have still been attached
to the
fin.Barring sabotage,I speculate severe rudder surface FLUTTER,
continuing a
damaging progression to the integrity of the fin, loss of the
vertical
surface and yaw control...side loading the engines along with
gyroscopic
rotation give way to both engine pylon failures, followed by complete
loss of
the flight.
I'm no rocket scientist but I'll bet my life that an initial event
caused the above.
(much like flight 800)...I've been a pilot for eighteen years
and a published
aviation photographer for eleven of those years.That vertical
fin was
designed to withstand the loads of spin recovery,50 times that
of wake
turbulence from a 747 400 WITH winglets which by design, REDUCE
wake
turbulence.
Thoughts from Peter (Bronx, NY) on February 3rd
Last week, I traveled to Santo Domingo, Dominican Republic on business on an American Airlines A300. Needless to say, I was quite reserved about even getting on the plane but thank God, everything went well. This was my first flight since the September 11th attacks and as would be expected, I was a bit nervous and visually checking everyone out.
Based on what I have read about this incident, I sincerely believe that this was an act of terrorism. My theory and thoughts on the incident seem to be supported by all of the eyewitness accounts .
Having just recently traveled to Santo Domingo on an A300, I took the opportunity to look over the plane and figure out, in layman terms, why there would be explosions, engines would fall off, and fire would be seen spewing out of one side of the plane. My thoughts went out to the victims of this incident as I sat in the plane and imagined what they had experienced that morning.
My theory about this incident is as follows. I understand it, there are aviation professionals who visit this site. Maybe you can discuss this with them for their opinion and not make these thoughts public. My intention is not that of creating hysteria but rather a great sense of getting to the truth of this matter.
a) On September 11, airliners were used as missiles on New York and Washington landmarks. On November 12, an Airliner was used as a bomb into a new York neighborhood.
b) The person(s) who executed this "bombing" knew two things: Security at Kennedy Airport, particularly for Caribbean flights, is lax, to say the least. I know this first hand. I have gone through those gates about 10 times in the past 4 years.
Two, that they only had minutes before they were over water and their "bomb" would not be as effective. They therefore had to execute their terrorism within the first 1 - 5 minutes of the flight.
c) While on the A300 recently, I noticed that there is a bathroom located on either side of the plane just forward of each wing. It is my belief that an explosive device, whether it was just placed there or was attached to a person, was detonated from this location. The person(s) would have entered the bathroom just prior to take off and stayed there. In this case, it would have been the bathroom on the right side of the plane.
d) Upon detonation, whether there was one or two of them, the
explosive blew a hole through the fuselage. Debris from this explosion
was sucked in by the right engine which in turn caused the fire
and smoke which was seen coming from the right side.
I think that we know the rest. The pilots lost control of the
aircraft, tried several maneuvers to no avail and the plane came
crashing down. In the process, the airplane lost tail, engine,
etc...
I believe that the NTSB and US government in general would be rather reserved and embarrassed to admit that this was an act of terrorism having already been on high alert and having deployed the Reserves just months prior.
As I have read on this site, the NTSB drew their conclusion before the black boxes were recovered and while the plane was still smoking. This is an absolute miscarriage of an investigation...drawing a conclusion before even beginning to look at the facts.
Furthermore, we are in a war environment. This investigation, if it really is one, is taking way to long to produce its conclusion. We can not afford the comfort of a stretched out, long term investigation with no clear conclusion.
We need the truth NOW!!!
Thanks for listening Vic. I hope to get the thoughts of your
professional readers.
I believe and trust that most (if not all) Americans would
be more
comfortable with the idea of the plane being taken down by a terrorist
than
by the tail falling off arbitrarily, or some random explosion
of unknown
origin on the plane.
Our policy makers and business leaders in government apparently
believe that
by misleading the public and distorting the facts of flight 587,
will make
the problem go away. This approach will not. If it was not so
serious, it
would be funny how these bureaucrats continue to fool the public.
Those of
us in the scientific community are not fooled by any of this.
What we are
seeing here is a decision based on potential bankruptcies of airlines,
cruise ship businesses and in short, another melt down of the
stock market. I
guess only the educated and strong survive.