As federal investigators focus on how heavy weight andimproper balance may have combined with a mechanical failure tocause the Jan. 8 crash of US Airways Express Flight 5481, observerssay those conditions could be recreated on any of thousands ofcommuter-plane flights that take off each day.
"I think it's one of the things that may make commuter flyingriskier," said Jim Burnett, a formerchairman of the National Transportation Safety Board, "especially when you're flying with a loaded airplance - the possibility that it could be out of weight or out of (itscenter of gravity) because of variations in the average passengerweight and the distribution of weight."
Federal investigators have said they are examining maintenancethat was done Jan. 6 on the Beech 1900's elevator assembly - whichcontrols the vertical movement of the plane's nose - as well asweight and balance issues in their probe of the crash.
Among the weight and balance concerns:
John Goglia, the NTSB member who headed the crash sceneinvestigation, said a member of the ground crew believed the planewas limited to 26 bags. He said Capt. Katie Leslie determined that all 31 checkedbags could remain on board.
According to Goglia, pilots and others interviewed in the investigation said they thought the plane "looked heavy" as it prepared for takeoff.Goglia also has said the early stages of the NTSB'sinvestigation indicated the 17,000-pound plane was 100 pounds belowits maximum weight and within one percent of the rearward limit forits center of gravity.
Given those conditions, said Paul Czysz, a professor emeritus ofaviation and engineering at St. Louis University, anymiscalculation of the center of gravity or loading that pushedunanticipated weight toward the rear could have made the planeunbalanced.
Problems could have included too many bags in the rearbaggage compartment or simply having several heavy-set men seatedin the rear.
Czysz and others said that airplane weight limits generally havea built-in safety margin, much like the "empty" line onautomobile gas tanks.
The location of a plane's center of gravity is not asforgiving. The FAA said a pilot may not fly a plane if its centerof gravity is beyond its forward or aft limit, because such a planecan be uncontrollable once airborne.
"It's a very black-and-white thing," Czysz said.
Mary Schiavo, a former inspector general for the FederalTransportation Department, said margins of error are thin incommuter planes like the 19-passenger Beech 1900.
"The small plane, being so light ... you don't have a lot ofleeway," said Schiavo, now a Los Angeles-based lawyer wholitigates air disaster cases.
A small-plane crash in the Bahamas that killed singer Aaliyahand eight others in 2001 was blamed in part on a plane that wasoverloaded by at least 700 pounds.
David Stempler, president of the Washington-based Air TravelersAssociation, a passenger-advocacy group, said he has heard foryears from commuter pilots concerned about weight and balanceissues. Last week's crash heightened worries, he said.
"I think what we need to do for planes under 30 seats is weighall checked and carry-on bags that go into the cargo compartment,"he said.
The industry likely would resist change. Air carriers alreadyoperate on extremely thin profit margins; telling them they mustreduce the number of passengers or the amount of cargo they carrywould only further harm a financially ailing industry.
Passengers already dealing with stepped-up security screeningsare unlikely to put up with being weighed before boarding a plane,and studies have shown people do not accurately self-report theirweight.
In-ground scales that weigh planes and measure their weightdistribution as they head for the runway - double-checking the workof pilots and load managers who currently perform such calculations- are prohibitively expensive.
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