Did laptop batteries aboard a UPS cargo plane catch fire, causing it to ignite into flames? The National Transportation Safety Board began looking into the question at a hearing Wednesday.
All three crew members on the plane were treated for minor injuries after it made an emergency landing shortly after midnight Feb. 8 at the Philadelphia airport.
Several other incidents have occurred in recent years in which lithium batteries - used in laptops and cell phones - have caught fire aboard airplanes.
Less than two months ago in Chicago, a spare laptop battery packed in a bag stored in an overhead bin started emitting smoke, chief crash investigator Frank Hilldrup of the NTSB testified Wednesday.
A flight attendant used an extinguisher and the bag was removed, but the bag caught fire on a ramp, Hilldrup said.
Investigators in the Philadelphia fire found that several computer laptop batteries were on board the plane, and that in many cases portions of the laptop batteries had burned, he said.
"It is not known at this time the role these batteries may have played in the fire," Hilldrup said.
Lithium ion batteries are sometimes referred to as "rechargeable" or "secondary" lithium batteries. They, along with primary or "non-rechargeable" lithium batteries, can present fire hazards because of the heat often generated when they are damaged or suffer a short circuit.
It is expected to take several months for the NTSB to reach a conclusion about the cause of the fire in Philadelphia, although several hazardous materials on board the plane have been determined not to be the cause. The NTSB is also examining other related issues such what can be done to make cargo flights safer and the overall emergency response to the incident.
In 1999, a shipment of lithium batteries ignited after it was unloaded from a passenger jet at Los Angeles International Airport. Another shipment erupted into flames in Memphis in 2004 when it was being loaded onto a FedEx plane bound for Paris.
In the case of the UPS cargo plane, the crew declared an emergency on approach into Philadelphia. Fire and rescue crews met the four-engine jet, a DC-8 that originated in Atlanta, when it touched down shortly after midnight.
Firefighters said the blaze was under control about four hours later, although the charred plane smoldered for hours.
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