Walter Vollenweider said that investigators were trying to find the "black boxes" of Flight 111 - the plane's flight data recorder and cockpit voice recorder - which contain records of the flight and cockpit conversations of the final 30 minutes.
The plane left New York's John F. Kennedy Airport at 8:18 p.m. EDT Wednesday and should have arrived in Geneva at 9:30 a.m. local time Thursday, Vollenweider said.
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Speaking at a news conference at JFK airport Thursday afternoon, he told reporters that officials did not yet know what caused the plane to crash about an hour into its flight, killing all 229 people aboard.
"Our priority right now is to the family of the passengers and crew," Vollenweider said. "We are working closely with the families to meet their individual needs. We are also making arrangements for a plane from Geneva to take families to Halifax."
The crew had reported problems with the flight after maintaining a cruising altitude of 34,000 feet -- usually the most stable time during a flight. The pilot wanted to make an emergency landing in Boston, but decided on trying to land in Halifax, Nova Scotia, since the plane was closer to that area at the time.
Vollenweider stressed that Swissair has had a good safety record.
"We're known for our excellent maintenance record," he said.
Vollenweider said that officials had not determined whether the disaster was caused by terrorists, but emphasized the reputed safety of the MD-11.
"The only thing we know is the MD-11 worldwide, the MD-11 in operation have an excellent record and we have reason at this point to doubt the safety of this aircraft," he said.
Swissair also announced that the plane's chief crew members, Capt. Urs Zimmermann and First Officer Stephan Loew, were both MD-11 instructors with a great deal of experience flying the tri-jet planes.
The flags at Zurich Airport were at half-staff Thursday after Swissair announced that all the passengers aboard the aircraft had died.