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Sonic boom: People woken by loud noise which 'shook houses' Sonic boom: People woken by loud noise which 'shook houses'
(about 2 hours later)
A loud sonic boom caused by RAF planes has woken people across north London and shaken houses. A sonic boom has woken people and shaken houses across parts of London and the northern Home Counties.
People tweeted that a loud "explosion" had woken them up at around 04:20 GMT - with houses shaking and reports of police sirens straight after. People tweeted that a loud "explosion" had woken them at around 04:20 GMT - with houses shaking and reports of police sirens straight after.
It is believed that loud noise was two RAF Typhoons launched from RAF Coningsby in Lincolnshire to an unresponsive aircraft. The noise was generated by two Royal Air Force Typhoons, which launched from Coningsby in Lincolnshire to investigate an unresponsive aircraft.
It was reported by people across north London, Hertfordshire and Bedfordshire. The sonic boom was heard across London, Hertfordshire and Bedfordshire.
The Met Police subsequently confirmed the bang was the result of RAF aircraft. London's Metropolitan Police subsequently confirmed the bang was the result of the RAF aircraft being cleared to go faster than the speed of sound.
Mil Radar which monitors Royal Air Force activity tweeted: It is understood the unresponsive aircraft later regained contact with air traffic control.
RAF jets are only given permission to go supersonic in emergencies, usually when they are required to intercept another aircraft.
Mil Radar which monitors Royal Air Force activity tweeted that the jets had been scrambled:
Janet from Hertfordshire told the BBC she heard a "huge thud" and felt her house shake at 04:17 GMT.
She wondered whether her boiler had blown up or a tree had fallen on the house, she said.
"I got up, looked around and out of the window, things looked fine," she said.
"I went downstairs, went from room to room looking for cracks in the walls and ceilings."
She went outside with a torch to check her roof and then checked the nearby road to see if there had been a crash, but saw "nothing and no sign of anyone else investigating", she said.
Kiran Topan tweeted this video:Kiran Topan tweeted this video:
Actor Logan Dean tweeted that he was among those who heard the noise:Actor Logan Dean tweeted that he was among those who heard the noise:
What causes a sonic boom?What causes a sonic boom?
When an aircraft approaches the speed of sound (768mph or 1,236km/h), the air in front of the nose of the plane builds up a pressure front because it has "nowhere to escape", said Dr Jim Wild of Lancaster University.When an aircraft approaches the speed of sound (768mph or 1,236km/h), the air in front of the nose of the plane builds up a pressure front because it has "nowhere to escape", said Dr Jim Wild of Lancaster University.
A sonic boom happens when that air "escapes", creating a ripple effect which can be heard on the ground as a loud thunderclap.A sonic boom happens when that air "escapes", creating a ripple effect which can be heard on the ground as a loud thunderclap.
It can be heard over such a large area because it moves with the plane, rather like the wake on the bow of a ship spreading out behind the vessel.It can be heard over such a large area because it moves with the plane, rather like the wake on the bow of a ship spreading out behind the vessel.