SkyScan World tweeted: “Royal Navy – Wildcat HMA.2 – #ZZ535 – #HARP0025. Currently shouting 7700 over English Channel.” Code 7700 indicates a “general emergency”. This usually means a technical problem with the aircraft.
It is not yet known why the 7700 signal was transmitted.
But SkyScan World said normal service on the flight has since resumed.
The Wildcat is the latest generation of multi-role helicopters specifically purchased to operate from Royal Navy frigates and destroyers.
As a carrier-based helicopter, Wildcat aims to provide commanders with a flexible attack capability that can be deployed to deal with a range of threats at sea and from the sea.
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.
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“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 Boris Johnson said he was enlisting in the Royal Navy to deal with the ongoing migrant crisis in the English Channel
The Prime Minister said: “This will be supported by new funding of £50 million for new boats, aerial surveillance and military personnel.
“In addition to the existing task force of patrol boats, helicopters, search and rescue aircraft, drones and remotely piloted aircraft, this will send a clear message to those piloting the boats: if you are risking the life of other people in the English Channel, you risk spending your own life in jail.
“People traveling to the UK will not be taken to hotels at public expense, but instead will be accommodated in accommodation centers like those in Greece, with the first of these due to open shortly. ”
Seven vessels plus smaller boats, a helicopter and drones will be made available to intercept migrant boats with up to 300 Navy personnel involved in the patrols.