A student pilot in a microlight aircraft and a Boeing 767 almost collided above Liverpool, a report on near misses in UK airspace reveals.

The 767 had just taken off from Manchester airport and was climbing to 18,000ft when it reached an air corridor normally reserved for large aircraft only, according to the Civil Aviation Authority and the Ministry of Defence.

But the microlight pilot had strayed into the zone - some 11,000ft above Liverpool - after his throttle had jammed and the two aircraft passed with 100ft of each other.

Aviation chiefs labelled the 10 March near miss a Category A incident - one of three occasions in the first half of 1999 when there was a real risk of an airborne collision.

The report expressed amazement that the microlight pilot could have risen so high without realising, and then failed to notice the climbing jet.

Runway emergency

However, the total number of near misses involving commercial passenger aircraft fell slightly in the first half of 1999 despite a 6% rise in hours flown.

The report from the UK Airprox Board said there were 44 near misses between civilian aircraft in the period, compared with 48 in January to June 1998.

Some 95 incidents were covered in the report (including military near misses) and 56 were found to have involved no risk of collision.

Airprox said aircraft safety had been compromised in 26 of the cases and there had been a risk of collision in nine other cases in addition to the three commercial air transport ones.

"As in 1998, more than three-quarters of the civil air transport incidents reported in the first half of 1999 were assessed as involving no risk of collision," said Gordon McRobbie, director of the UK Airprox Board.

"Compared with figures for the same period in 1998, the volume of flying went up by 6% while the number of airprox [air proximity incidents] went down by 5%.

"While it is too early to reach any long-term conclusions on trends, this has to be good news."

In a second category A case, which was reported recently by the Air Accidents Investigation Branch, a departing BAe 146 aircraft almost collided on the ground with an arriving two-seater Piper aircraft at Birmingham airport.

The third such incident was on 22 June near Bournemouth airport when an ATR 72 passenger aircraft and another Piper came within 400 yards horizontally of each other.