According to the Vietnamese Defence Ministry and the Helicopter Services Company at the Wycombe Air Park in Buckinghamshire, where the collision occurred, Captain Nguyen Thanh Trung was taking an advanced helicopter training session on a CabriG2.
He was in the student’s seat and his mentor was on the pilot’s seat.
Contact with the helicopter was lost 15 minutes after it took off.
The Helicopter Services Company said that the helicopter was hit in the rear by a light two-seat aircraft Cessna, which was also on a training session, at the height of 1,000 feet or about 330m.
The mid-air collision killed all four people on the helicopter and the aircraft, according to UK media reports.
The crash is being investigated.