A security scare on board a Ryanair flight that was escorted by RAF jets and saw flights at Stansted Airport grounded was a suspected hoax, the airline said.
Passengers were evacuated after plane was diverted from its route between Kaunas in Lithuania and Luton Airport in Bedfordshire, and forced to land at Stansted, Essex, at around 8.55am on Wednesday.
Social media users posted pictures of armed police on the scene and Essex Police said officers were investigating.
A Ryanair spokesman said: “This flight from Kaunas to London Luton diverted to London Stansted in line with procedures after Lithuanian authorities received a suspected hoax security alert.
“The aircraft landed normally at Stansted and customers will be transferred to Luton by coach when cleared to do so.”
A spokesman for the airport said all flights had now resumed after being held for about 10 minutes.
The track on FlightRadar24 of Ryanair flight FR2145, flying from Lithuania to Luton, which has been escorted into Stansted Airport by RAF jets (FlightRadar24/PA)
The RAF Typhoon jets were sent from RAF Coningsby, Lincolnshire to intercept the aircraft, the Ministry of Defence said.
A sonic boom echoed across the Suffolk skyline when the jets were scrambled, Suffolk Police confirmed.
An RAF spokesman said: “The RAF can confirm Quick Reaction Alert Typhoon aircraft were launched this morning from RAF Coningsby to intercept a civilian aircraft.
“The aircraft was safely escorted to Stansted Airport. The Typhoon aircraft were authorised to transit at supersonic speed for operational reasons; any inconvenience caused to local residents is regretted.”
Emergency services on standby at Stansted in Essex after a Ryanair plane from Lithuania to Luton was escorted to the airport by RAF jets (Victoria Jones/PA)
Stansted is a designated airport for dealing with hijacks and major security alerts.
Such incidents are normally dealt with in a remote part of the airfield to the north west of the terminal building.
An RAF Typhoon jet escorted a Pakistan International Airlines plane to Stansted in February.
An airline spokesman at the time said UK authorities had “received some vague security threat through an anonymous phone call”.
Essex Police said that incident was “not believed to be a hijack situation or terror matter”.
Typhoon pilots are on standby 24 hours a day to defend UK airspace.
Squadrons are based at RAF Coningsby, covering the south of the country, and RAF Lossiemouth in Moray, to cover the north.
QRA crews can take off within minutes to intercept aircraft which have caused concern. This can be because they are Russian military aircraft, or civilian planes which have stopped communicating with air traffic control, are not following their flight plan or have sent an emergency signal.
On some occasions pilots are given permission to fly at supersonic speeds, which may result in a sonic boom, to reach the aircraft as soon as possible.
Ministry of Defence figures show that QRA aircraft were launched on 12 days in 2015, eight in response to Russian aircraft and four to investigate other planes.