A British Aerospace Hawk T.2, registration ZK013, was flying over Wales on April 22. At 12:55 p.m. the flight of the British Aerospace Hawk T.2 from Anglesey Airport, part of the RAF Valley, began.
Twitter accounts reported the jet “screamed 7700” around 1:10 p.m.
According to Flightradar24, the jet then landed at 1:19 p.m., after a total flight time of 24 minutes.
The RAF jet reached an altitude of 24,650 feet according to adsbexchange.com.
It is unclear what caused the British Aerospace Hawk T.2 to ‘squawk 7700’.
Minutes earlier, an RAF E-3 Sentry aircraft emitted an urgent “scream” from 7,700 to 7,000 feet in the air.
Less than a month ago, an RAF military airbus transmitted the same signal while flying over Gloucester at an altitude of 5,000ft.
The plane took off from RAF Brize Norton at 4.17pm on Thursday March 27 and made a series of circles around Cheltenham.
However, the RAF military airbus signal was later found to be a pre-planned test signal.
A Royal Navy spokesman said: “Today a wildcat helicopter was on a routine sortie over Somerset levels by a qualified test pilot.
“During this pre-planned flight, a routine transponder test was performed.”
Explaining the use of the 7700 signal, RAF Lossiemouth previously said the practice was “not uncommon”.
He explained that its use allows “to ensure the safe recovery” of an aircraft.
The official RAF Lossiemouth account posted on Twitter: “Setting a squawk of 7700 is not uncommon in these situations and is merely a precaution.
“The word ’emergency’ can sometimes worry those unfamiliar with aviation, but these procedures ensure the safe recovery of any aircraft with trouble in the air.”
Writing for Flightradar24, Ken Hoke, a Boeing captain, explained that “chirping” is a way for a plane to declare 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 an aircraft problem, a medical problem or something else.
“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 have a problem, I’ll tell them the problem, declare an emergency by radio and land vectors immediately.”
It comes after a Scandinavian airline flight from Stockholm to Dublin was forced to land in Edinburgh after emitting an emergency ‘cry’.
The flight made a sharp turn to Edinburgh instead of continuing its journey to Dublin.
Squawk Tracker via Twitter reported that the plane issued the emergency signal “7700” at 10:06 a.m.
The cause of the hijack is unclear at this time, although a 7700 code usually refers to an engineering issue.
The flight departed 15 minutes late at 9.35am and was due to arrive in Dublin at 11.10am.