US Airways Express Flight 5481 crashed 37 seconds into itsflight Wednesday, preliminary data show. A final conclusion aboutwhat happened could take months or even years after investigatorsfinish reviewing maintenance records, testing the charred debrisand running computer simulations.
In four days, investigators looked at factors such as theplane's weight and balance, recent maintenance and whether a largerjet could have buffeted it with enough turbulence to cause thecrash.
They scrutinized a West Virginia facility that serviced theaircraft Monday night and interviewed baggage handlers about apre-takeoff discussion of how much baggage could go on board.
The crash team from the National Transportation Safety Boardwill ship some key parts to Washington, D.C., where technicians inthe board's materials lab can examine metal parts for cracks withmicroscopes, X-ray machines and ultrasound equipment, said BillWaldock, an aeronautical science professor in Prescott, Ariz., whohas assisted in NTSB probes.
Often in a crash, two pieces of metal bang together and leave ascar known as a "witness mark," he said. From these marks,investigators could tell the position of the plane's elevator andhorizontal stabilizer at the time of impact.
Technicians will analyze the cockpit voice and flight datarecorders. Inside the so-called "black boxes" are memory modules,either on tape or computer chips.
Investigators can do a sound spectrum analysis of the voicerecorder, searching for vibrations and other noises, Waldock said.
They will plot the plane's actions from the flight datarecorder, which will then be matched with the cockpit voicerecording.
"That gives investigators a good picture of what transpiredduring the flight, and what kind of action and reaction the crewtook," said Greg Feith, a former senior NTSB air safetyinvestigator who led the probe of a 1994 USAir crash in Charlottethat killed 37 people.
The engines will be sent to the manufacturer's facility inCanada, where NTSB investigators will take them apart.
After about six to nine months, the NTSB probe will lead to acollection of the facts, without any analysis.
Then investigators will analyze that data and compile a draft ofthe final report, which takes another six to nine months. If theagency finds problems needing immediate attention, the NTSB willissue emergency recommendations.
The initial report, which includes a probable cause,recommendations and any other conclusions, is then reviewed by thesafety board in a public meeting. The board will discuss the reportand vote on the findings.
Probing the Alaska Airlines crash off the coast of Californiatook almost three years, ending just last month.
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