Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: TUESDAY, January 24, 1995 TAG: 9501240124
SECTION: NATIONAL/INTERNATIONAL PAGE: A1 EDITION: METRO
SOURCE: CHICAGO TRIBUNE
DATELINE: PITTSBURGH LENGTH: Medium
By itself, the ``wake vortex'' from a Delta Air Lines passenger plane should not have caused the crew of the USAir Boeing 737 to lose control, the experts said. But investigators from the National Transportation Safety Board are trying to determine whether it could have triggered a chain of events that caused the fatal plunge near Aliquippa, Pa., on Sept. 8.
All 132 people aboard the plane, bound from Chicago to Pittsburgh, were killed in the worst U.S. aviation accident in seven years.
Investigators have learned that the Delta plane, a Boeing 727, had preceded the USAir jet on the approach to Pittsburgh International Airport by about 70 seconds on a path 300 feet higher.
Big planes generate a wake vortex - a swirling mass of air - from the trailing edge of each wingtip, said George Green, a NASA expert who testified at the NTSB hearing in Pittsburgh. The strong winds, also called ``horizontal tornadoes,'' descend from the planes that create them, he said.
James Kerrigan, an aerodynamics, stability and control expert with the Boeing Commercial Airplane Group, the 737's manufacturer, said any turbulence from the Delta jet would have hit Flight 427 at just the time that computer simulations indicate it first experienced control problems.
Earlier at the hearing, a computer-generated video depicting the plane's nose dive was projected onto a huge screen as more than 100 survivors of crash victims, sitting in a reserved section of the hearing room, watched. One woman dabbed her eyes with a tissue while another looked at the floor and choked back tears.
The tape from Flight 427's cockpit voice recorder was not played at the hearing, but the safety board released a printed transcript of what was said in the plane's final hour, including the 26 seconds between the onset of the mysterious control problems and the crash.
Everything seemed normal on USAir Flight 427 until three clicks were heard in the cockpit. ``Sheez,'' the captain said.
A second later, a thump, then clicking were audible. As someone in the cockpit began breathing hard, a second thump and more clicks were heard. It took less than a half-minute for the plane to roll to the left and plunge a mile to the ground.
The clicks and thumps have baffled investigators.
``We've listened to them over and over again and we can't tell what they are,'' said Thomas Haueter, the NTSB's chief investigator for the crash.
Nor could the crew, apparently.
``Whoa,'' Capt. Peter Germano said.
``Hang on, hang on, hang on,'' he said a second later as a wail signaled the disconnection of the autopilot. ``What the hell is this?''
``Oh [expletive]'' First Officer Charles B. Emmett said.
Germano or co-pilot Charles Emmett III then said, ``Traffic, traffic, traffic, traffic.'' The term typically is used to describe other airplanes in the area, but investigators believe no other craft were in the immediate vicinity.
``Oh God, oh God,'' Germano said.
Screams were heard next and, less than a half-second before the recording ended, Emmett said a simple ``No.''
The Associated Press contributed to this story.
Keywords:
FATALITY
by CNB