MILITARY helicopters came close to crashing into light aircraft twice in a matter of weeks over the same disused airfield.

Reports from air safety watchdog the UK Airprox Board showed Apache helicopters had near misses with biplanes over the former Birch Airfield and August and September last year.

In the first incident, the Apache pilot had climbed to 1,500ft when a fixed-wing aircraft - a PA28 - began converging from the right.

The pilot initially believed the plane was just 50ft higher than the helicopter and passed by 100ft without altering its course.

However radar readings showed they had actually been 400ft apart.

The Apache crew had been given no prior warning about the plane after they had left Wattisham Airfield in Suffolk - the largest operational Army airfield in the country.

A report into the incident said: "The board agreed the Apache pilot had seen the PA28 later than desirable and that this, accompanied by probable startle-factor, may have resulted in the Apache crew believing the PA28 was closer than it actually was.

"Some members wondered whether the radar replay was of the correct incident, but there were no other aircraft visible in that area at that time and so it could only be concluded that the Apache crew had perhaps been somewhat startled by the incident and had probably underestimated the separation."

In the second incident, an Apache crew spotted a small plane 500m away from them which then performed a left turn.

They passed within 60m.

The report said: "This is interesting in the fact that it is the second incident within as many weeks in the vicinity of the same disused airfield who were both flying similar profiles to the disused airfield.

"This highlights several issues of a recurring theme.

"In determining the cause, the board quickly agreed this had been a late sighting by both pilots.

"However, the assessment of risk caused some debate, with some members believing that

the radar separation of 200ft and 0.1nm mean that safety had been much reduced below the norm.

"Others felt that although safety had been reduced, both pilots had been able to take timely and effective action such that there had been no risk of collision."