DUBAI, United Arab Emirates (AP) — Emirati investigators leading the probe into the deadly crash of a UPS plane in Dubai have sent the Boeing 747's flight data recorders to the U.S. as they try to determine what brought the three-year-old jet down.
Pilots onboard United Parcel Service Flight 6 reported smoke in the cockpit about 20 minutes after taking off from Dubai. They tried to return to the Gulf city-state but were unable to land on their first attempt and crashed into a military base shortly afterward. Both crew members were killed.
The UAE's General Civil Aviation Authority is leading the investigation with help from investigators at U.S. National Transportation Safety Board.
GCAA Director-General Saif al-Suwaidi told The Associated Press on Tuesday that both of the plane's flight recorders, known as "black boxes," were sent to a laboratory in the U.S. late last week for further analysis "under the custody of GCAA staff."
Investigators said they found the plane's cockpit voice recorder about six hours after the crash. The other black box — the digital flight data recorder — was recovered in "reasonable" condition days later.
Information on the devices could provide clues into what caused smoke to fill the cockpit shortly after the plane departed Sept. 3 on a flight to a UPS Inc. hub in Cologne, Germany.
For reasons still unclear, the crew was unable to switch their radio frequency back to the Dubai channel and could not communicate directly with air traffic controllers there as they attempted to land. They instead had to relay information through air traffic controllers in the nearby Gulf nation of Bahrain.
Data on the recorders will likely be compared with information already received from a sophisticated data transmission system installed on the plane. The system, known as an airplane health management system, is able to transmit performance information rapidly via satellite to UPS's airline operations headquarters in Louisville, Kentucky.
Accident investigators have told the AP that a fire appears to have begun in a cargo compartment just forward of the starboard wing. One theory being considered is that the plane may have been carrying lithium-ion batteries in the cargo hold. If a battery short-circuits, it can catch fire and ignite others.
Shortly after the crash, Al-Suwaidi said it appeared the plane was mainly carrying electronic goods, including toys and computer accessories. The manifest stated the 747-400 was carrying general cargo, he said.