"The typical cruise speed of a Boeing 767-200 at 35,000 feet is 530 m.p.h. The lower the plane goes, however, the thicker the air becomes, so the slower the plane must travel to avoid excessive stress.
"Flying a Boeing 767 straight ahead at 1,000 to 1,500 feet would not be too difficult, even at more than 580 m.p.h., and it would most likely not threaten the structural integrity of the plane, a
half a dozen pilots and a Boeing. .spokeswoman said.
"But accurately turning the plane at that speed and maintaining the proper pitch, or up and down movement, is difficult, the pilots said, particularly for a novice pilot, and turning at that speed would have put excessive stress on the plane.
"An automatic pilot device could have directed the hijacked planes to Manhattan, if the hijackers knew how to enter certain coordinates into the computerized flight management system. But as they approached the city, the hijackers. .almost certainly had to take manual control of the. .aircraft, because the automatic pilot in mavigation mode is not accurate enough to target the center of building, pilots said.
"Video of the approach of United Flight 175 to the south tower shows that it banked westward in the final moments, its right wing going up, its left wing down. That maneuver may have been intended to maximize damage to the building.. .But it has been interpreted by some pilots as a sign that the hijacker nearly missed the tower.
""It was unfortunate luck," said Richard Fariello, a retired T.W.A. captain who works as a consultant to NASA. "The way he was headed, he could have just clipped it perhaps with one wing. There is a good chance that would have been the. .case."
http://www.pprune.org/rumours-news/3903-wtc-ua-175-speed-exceeded-767-design-limits.html
