A Ryanair passenger jet was escorted into Stansted airport near London by two RAF fighter jets after a suspected hoax security alert.
Flights were temporarily grounded at the hub as the plane was redirected from its route between Kaunas in Lithuania and Luton airport in Bedfordshire.
Essex police took over the investigation once the flight landed and later confirmed nothing suspicious was found on the aircraft.
A Ryanair spokesman said: “A 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.”
Essex police said the plane landed at 8.55am and by 11am they had completed enquiries and found nothing suspicious.
Chief Insp Richard Phillibrown said: “We take all intelligence received regarding potential threats to public safety very seriously. The safety of the public is paramount.”
An RAF spokesman said: “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.”
RAF aircraft are authorised to travel at supersonic speed over land only in emergency situations.