Homeland Security Department spokeswoman Katie Montgomery said that Virgin Atlantic Airways Flight 45 was en route from London's Heathrow Airport to John F. Kennedy International Airport in New York, when the aircraft began emitting code 7500, which indicates a hijacking is in progress.
"It's a false alarm," said Virgin Atlantic spokeswoman Brooke Lawer. "The transponder sent out a false alert."
Lawer said the airline has been in contact with the captain and the flight crew.
"The flight deck door is locked and secured," she said.
CBS News reports that the flight would not be allowed to be in U.S. air space after submitting the alarm. It had been planning to land in New Brunswick before it was found that the runway there was not long enough.
CBS News also reports that the two Canadian jets were launched to intercept the plane at 9:50 a.m.
After the Sept. 11, 2001, terror attacks, airlines were required to install bulletproof doors to the cockpit and to keep them closed to prevent hijackers from taking over planes.
North American Aerospace Defense Command Lt. Cmdr. Sean Kelly said Canadian fighter jets escorted the plane to Halifax, Nova Scotia, where it landed without incident.
Montgomery said the Homeland Security Department is checking other indicators to confirm the pilots' information.