The other incident that Dr Clarke says defies rational explanation occurred in April 1956, shortly before the Suez Crisis. Radar at RAF Bentwaters in Suffolk detected a number of unexplained blips, including one travelling at hypersonic speed. Airmen on the ground and travelling in a transport plane over the base saw bright lights, but when aircraft were sent to investigate, they could see nothing. Later that night, more UFOs were seen on radar at two other East Anglian airbases, and again on the following night. RAF Jets were sent up to intercept the UFOs and although they found it on their radar, they could not spot the aircraft.