Investigators Leave Charlotte Crash Scene, Though Work Far From Over
Posted January 12, 2003 11:51 a.m. EST
CHARLOTTE, N.C. — Field investigators packed up debris and headed home Sunday for more detective work into the cause of a fatal commuter airline crash that killed all 21 people aboard.
US Airways Express Flight 5481 crashed 37 seconds into its flight Wednesday, preliminary data show. A final conclusion about what happened could take months or even years after investigators finish reviewing maintenance records, testing the charred debris and running computer simulations.
In four days, investigators looked at factors such as the plane's weight and balance, recent maintenance and whether a larger jet could have buffeted it with enough turbulence to cause the crash.
They scrutinized a West Virginia facility that serviced the aircraft Monday night and interviewed baggage handlers about a pre-takeoff discussion of how much baggage could go on board.
The crash team from the National Transportation Safety Board will ship some key parts to Washington, D.C., where technicians in the board's materials lab can examine metal parts for cracks with microscopes, X-ray machines and ultrasound equipment, said Bill Waldock, an aeronautical science professor in Prescott, Ariz., who has assisted in NTSB probes.
Often in a crash, two pieces of metal bang together and leave a scar known as a "witness mark," he said. From these marks, investigators could tell the position of the plane's elevator and horizontal stabilizer at the time of impact.
Technicians will analyze the cockpit voice and flight data recorders. Inside the so-called "black boxes" are memory modules, either on tape or computer chips.
Investigators can do a sound spectrum analysis of the voice recorder, searching for vibrations and other noises, Waldock said.
They will plot the plane's actions from the flight data recorder, which will then be matched with the cockpit voice recording.
"That gives investigators a good picture of what transpired during the flight, and what kind of action and reaction the crew took," said Greg Feith, a former senior NTSB air safety investigator who led the probe of a 1994 USAir crash in Charlotte that killed 37 people.
The engines will be sent to the manufacturer's facility in Canada, where NTSB investigators will take them apart.
After about six to nine months, the NTSB probe will lead to a collection of the facts, without any analysis.
Then investigators will analyze that data and compile a draft of the final report, which takes another six to nine months. If the agency finds problems needing immediate attention, the NTSB will issue emergency recommendations.
The initial report, which includes a probable cause, recommendations and any other conclusions, is then reviewed by the safety board in a public meeting. The board will discuss the report and vote on the findings.
Probing the Alaska Airlines crash off the coast of California took almost three years, ending just last month.