A helicopter was metres away from colliding with another aircraft after inadvertently taking off from the wrong runway at Denham Aerodrome, according to an investigation report.

A report by the Airprox Board stated the helicopter pilot “immediately realised her mistake” after using the wrong runway and entered airspace above Wycombe Air Park.

However she became so “absorbed” in flying her AS350 aircraft out of the danger zone she did not see the small aeroplane around 60 metres away from her.

The pilot of the C152 aircraft was informed by the Wycombe control tower that there was a helicopter crossing, and he watched it pass “200ft in front at the same level.”

He assessed the risk of collision as “high” according to the report, however he felt the helicopter was moving fast enough for him to not carry out “avoiding action”.

The report stated: “The AS350 pilot reports that she departed Denham, but had inadvertently taken off from RW24 instead of RW06.

“The tower called and she immediately realised her mistake and apologised. They replied that she wasn’t the first pilot to do it.

“But she was now concerned that she would get into trouble and was fully absorbed in flying the aircraft to get out of the area of confliction and not infringe London Airspace.

“She was shaken by the event and didn’t see any TCAS indications, or the other aircraft involved in the Airprox, although she noted that they could well have been there.”

The report stated “she was probably rattled” after taking off from the wrong runway and the board wondered “whether this had caused a continued lack of concentration and mistakes.”

The report added: “This incident should serve as a reminder to all pilots to ensure that they were in the correct frame of mind to conduct their flight.

“If she was distracted by the takeoff incident (it appeared that her navigation and lookout had been severely compromised) then it may have been wiser to land again at Denham, compose herself and then start the flight again.”