The jet, a Falcon 20e G-FRAF, sent the code 3,400ft in the air near the coast of Bournemouth, with flight tracking data showing it had flown over the English Channel just before. It is not yet clear what the destination of the aircraft was or why the 7700 signal was transmitted.
Boeing 757/767 pilot Captain Ken Hoke explained that shouting is a plane’s way of declaring an emergency with traffic control, so it can receive ground assistance.
He said: “If a crew resets their transponder to emergency code 7700 (shouting 7700), all air traffic control facilities in the area are immediately alerted that the aircraft is in an emergency.
“It’s up to the crew to let ATC know what the exact situation is.
It could be a plane problem, a medical problem or something else.”
READ MORE: RAF Typhoon fighter plane emits code ‘7700’ 24,000ft over UK on high alert midair
Outlining how a squawk emergency is handled by the aircrew in flight, he told Flightradar24: “In some cases a crew may not choose to change their transponder to 7700 (it’s not mandatory ). If I speak to Chicago Approach and I have a problem, I will tell them the problem, declare an emergency by radio and land the vectors immediately.”
“In most ’emergencies’ we are not in a great rush.
“Unless it’s smoke, fire or a lack of fuel, we can usually take our time to assess the problem.
“If we’re on a cruise flight and get some kind of warning message, we can spend several minutes troubleshooting the issue with a checklist.”
Capt Hoke added: “Weather permitting, we can contact dispatch and maintenance personnel by radio or SatComm for further guidance.
“If we determine the aircraft’s capabilities have been reduced, we may decide to declare an emergency and determine the best place to land.”
Earlier on Tuesday, another plane sounded an alert over British skies.
The aircraft is a highly agile model, designed to be an extremely combat-effective fighter.
It undertakes air-to-ground strike missions and is compatible with an increasing number of different armaments and equipment.
Last week, a US Air Force Boeing KC135 which took off from RAF Mildenhall Air Base in Holywell Row, UK, was forced to return to base after sending a squawk code en route to Romania.
The emergency occurred as the plane was about to reach Bucharest, before circling over Brasov.
An air traffic monitoring Twitter account claimed that during the flight the plane had to shut down an engine.
When the tracking data ended, the plane appeared at 625ft just above Lakenheath.