TWO policemen were killed when their microlight collided with a helicopter, sending them plummeting to their deaths.

Police Sergeant Ian Alexander, 44, a qualified microlight pilot with 15 years flying experience, had taken off in the microlight from an airstrip in St Albans with his friend PC Andy Morton, 41, from Cranfield, in Bedfordshire.

The off-duty officers, from Hertfordshire Constabulary's road traffic policing unit, were returning from Hunsdon to Plaistow Farm near Potters Crouch when the fatal crash happened at 12.50pm on July 6 last year.

Hatfield Coroners Court heard this week how the aircraft had plunged to the ground after it was "catastrophically" damaged in a collision with a Robinson R22 helicopter at a combined speed of up to 140mph.

Speaking at the inquest, Andrew Robinson of the Air Accidents Investigation Branch (AAIB) said the microlight's wing had been severed by the helicopter blades. There was nothing Mr Alexander, who was born in St Albans, could have done to control it.

A post-mortem examination confirmed the pair had died from multiple injuries as the Hybrid 44XLR Microlight ploughed into woods off Dixons Hill Roads, Welham Green.

Dr Peter Ticehurst, a glider pilot, was in a car travelling north up the A1M when he saw both aircraft heading towards each other. Neither appeared to deviate from their course.

He said: "As they got closer, my reaction was Crikey. They're going to collide' and a few seconds later they did. The wings appeared to fold up above the aircraft."

Helicopter pilot Simon Woods, who had been flying helicopters for 25 years, spotted the microlight seconds before impact. He said: "It was straight ahead, very slightly below me and was coming towards me. I tried to move the helicopter left.

"There was a very loud bang and a fierce thump to my left foot. I realised we must have hit it. There was a brief moment of being stunned and I became aware the windscreen was missing."

He made an emergency landing and mayday signal in a nearby field. Passenger Stephen Messenger, who was on his first flying lesson, a 30th birthday present from his wife, ran to a house and raised the alarm.

The helicopter, which was operated by Cabair, had left Elstree Aerodrome and flown to Enfield. It crossed the A1 south of the M25, headed towards St Albans then east towards Potters Bar and Hatfield.

The jury heard how the pilots had been on different radio frequencies and that it may have been difficult to see each other as the white helicopter was set against fluffy clouds and the black microlight against shadows on the ground.

Recording verdicts of accidental death, coroner Edward Thomas backed recommendations made by the AAIB to the Civil Aviation Authority to carry out more research into the visibility of aircraft.

After the hearing, Mr Morton's parents, Michael and Barbara Morton, said: "Nothing can bring Andrew back. It was helpful hearing all the facts, but it doesn't change anything we've lost a son and three boys have lost a father. Every day is still very hard."

Mr Alexander's wife Sarah, of Hemel Hempstead said: "We'll probably never know the full facts because the only two people who truly know what happened are not here today. I hope guidelines are put in place to ensure such a tragic accident can never happen again."