reply to post by mikelee
, we (in the aviation community) are well aware of USAir 427.
Your short description only mentions its impact velocity as 261 knots. This is significantly slower than United 93's velocity at impact.
(Recall the formula for energy/velocity relationship in momentum, and kinetic).
Further, it's important to note the very different qualities of the terrain where each hit, and the separate reasons
for the two
accidents, for comparison.
(USAir was in controlled flight, being radar-vectored for an Approach to the Pittsburgh Airport, level and configured for "maneuvering speed"
prepatory to commencing the final approach procedure. Flaps/slats extended, and airspeed around 170-180 knots. The roll-over, and loss of control,
with the nose pointing at the extreme down attitude, relative to the horizon --- and the crew's inability, due to the initial low altitude above
ground, to effect recovery in time, meant that the airspeed built up due to gravity, alone. NOT from increased thrust from the engines, nor from
intentional maneuvering to hit the ground).
There was one other similar Boeing 737 rudder PCU-related crash, United 585 in Colorado Springs. Even lower altitude, airplane was fully configured
for landing, (speed about 140 kts) and the drop was only about 1,500 feet, from the within the turn from base leg to final approach.
Some HIGH-velocity "intact" (as opposed to in-fli8ght break ups) airplane impacts are PSA 1771, ValuJet 595, and SwissAir 111...and of course,
*(And the recent Iran flight)*.
PSA into a combination hard-packed dirt/rocky hillside/field, ValuJet into a swamp, and the other two into the ocean. *(Iran, into a plowed
Three loss of control due to onboard fires, and one a suicidal plunge initiated by the working and scheduled relief First Officer --- on EgyptAir.
PSA was also a suicide, disgruntled former employee.
Hitting the surface of the water at high speed in very much like hitting a solid surface, in that a great deal of fragmentation occurs. Look at
photos of the debris reconstruction that are available.
Comparing examples of airplane carshes, though, is not always helpful, since rarely are any two exqactly similar. Many variables at work.
But, it does provide some basis to extract clues, and inferences.
[edit on 8 July 2010 by weedwhacker]