A loud noise thought to be a sonic boom, which was heard by many people across England, was caused by RAF jets escorting a plane.
The plane had two people onboard and was flying from Iceland to Nairobi, Kenya via Southend when it lost contact and had to be escorted to Stansted airport, police said.
In a statement, the force said: “A flight has been diverted to Stansted airport after communications with the pilot had been lost. The plane was escorted to the airport by RAF jets and landed shortly before 12.50pm [on Saturday].
“Officers are engaging with the pilot and inquiries are ongoing.”
The Ministry of Defence (MoD) confirmed that Typhoon fighter jets were sent from RAF Coningsby in Lincolnshire to help the aircraft. A spokesperson said: “Typhoon aircraft from RAF Coningsby offered assistance to a civilian aircraft and were authorised to fly supersonic.”
The MoD said it always had jets under a “quick reaction alert” that respond to any aircraft that cannot be identified or is not communicating with either civilian or military air traffic control.
Typhoon fighter squadrons are positioned at RAF Coningsby, RAF Lossiemouth in Scotland and in the Falkland Islands.
The sound was heard across Leicestershire, Northamptonshire and in parts of Oxfordshire.
Leicestershire police said they had received “numerous calls” but there was no need for concern.
Many people went on social media to describe the sound. Plane spotters suggested it may have come from an RAF Typhoon fighter jet scrambling to intercept another aircraft in distress.
The RAF’s Airbus Voyager, the only model of in-flight refuelling plane used by the air force, was being tracked by at least 1,440 people on Flightradar24 – a site that tracks aircraft in real time.
Leicestershire police tweeted: “We have received numerous calls in relation to a large explosion sound heard from various parts of the city and county. We like to reassure you that there is no concern however thank you for your immediate response to us.”
A sonic boom is caused when planes fly faster than the speed of sound, which at ground level is about 761mph (1,225km/h).
When travelling at this speed, also known as Mach 1, the aircraft displaces the air and creates pressure waves that become compressed and are then released in a shock wave.
As long as the aircraft is flying at Mach 1 it will generate continuous sound waves, known as a boom carpet. An aircraft flying at 20,000ft would create a sonic boom cone 20 miles wide.
Loud boom heard all across central England a few minutes ago at 12.12pm - reported in Leicester, Northampton, Towcester, Banbury, Bicester, Oxford… Facebook folk saying sonic boom but who knows? Made me jump anyways
— Matthew Teller (@matthewteller) March 4, 2023
Northamptonshire police, commenting on the reports, said: “Police and fire services in Northamptonshire have received numerous calls in relation to a large explosion sound heard from various parts of the county.
“We would like to reassure people there is no concern, but thank you for contacting us.”
