The jet, a Falcon 20e G-FRAF, sent the code at 3,400ft in the air near the Bournemouth coast, with flight tracking data showing it had overflown the English Channel just before. It is not yet known what the plane’s destination was nor why the 7700 signal was transmitted.
Boeing 757/767 pilot Captain Ken Hoke explained squawking is a way an aircraft declares an emergency with traffic control, so they can receive on-the-ground assistance.
He said: “If a crew resets their transponder to the emergency code of 7700 (squawking 7700), all air traffic control facilities in the area are immediately alerted that the aircraft has an emergency situation.
“It’s up to the crew to let ATC know what the exact situation is. It may be an aircraft problem, medical issue, or something else.”
“In some cases, a crew may not elect to change their transponder to 7700 (it’s not required). If I’m talking to Chicago Approach and have a problem, I’ll tell them the problem, declare an emergency over the radio and get vectors to land immediately.”
Providing insight into how a squawk emergency is handled by in-flight crew, he told Flightradar24: “In most ’emergencies’ we aren’t in a big hurry.
“Unless it’s smoke, fire, or low on fuel, we can usually take our time to evaluate the problem.
“If we are in cruise flight and get a warning message of some sort, we may spend several minutes working the problem with a checklist.
“If time permits, we can contact dispatch and maintenance personnel via radio or SatComm to get additional guidance.
“If we determine that the capabilities of the aircraft have been reduced, we may elect to declare an emergency and figure out the best place to land.”
Earlier on Tuesday, another aircraft issued a squawk alert in British skies.
The RAF Eurofighter Typhoon, which is a European multinational twin-engine, issued the alert from 24,000ft as it travelled between Aberdeen and Inverness in Scotland.
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