A pilot continued to fly a plane after thinking his co-pilot who died in the cockpit was joking with him.
The Air Accidents Investigation Branch (AAIB) said the pilot thought his colleague - a flying instructor who he knew well - was pretending to be asleep during the incident over Blackpool on 29 June last year.
Shortly after taking off, the 57-year-old instructor’s head rolled back as he suffered a sudden fatal heart attack, but the pilot carried on flying.
After the pilot landed the Piper PA-28-161 plane, the instructor was still resting on his shoulder and not responding, which is when he realised something was wrong.
Before the short journey around Blackpool Airport, a second pilot had been requested for safety reasons due to windy weather, and the instructor agreed to join the flight.
The instructor was talking normally with the pilot while the plane was still on the ground, the AAIB said, adding that he had been his “normal cheerful self and there were no indications that he was feeling unwell”.
The report went on: “The pilot recalled that shortly after take-off from Runway 28 the instructor’s head rolled back. The pilot knew the instructor well and thought he was just pretending to take a nap whilst the pilot flew the circuit, so he did not think anything was wrong at this stage.
“He proceeded to fly the aircraft round the circuit. As he turned on to base leg the instructor slumped over with his head resting on the pilot’s shoulder. The pilot still thought the instructor was just joking with him and continued to fly the approach.”
A post-mortem examination concluded that the instructor, who had passed a medical four months earlier, died from acute cardiac failure.
The AAIB report added that current medical assessments were acceptable but risks “can never be reduced to zero”.
It investigated the incident so lessons could be learned. Its analysis said: “On this occasion he was flying with a qualified pilot who was able to land the aircraft safely. However, had this occurred on another flight the outcome could have been different.”