I am not sure that the authorities in Europe have thought through the problem of wake turbulence, which will be caused by the heaviest transport aircraft in the RVSM aerospace over Europe.

I recently had a very salutary experience over the North Atlantic when routing behind a Jumbo. We had been overtaken very slowly by the Jumbo, so we elected to stay in trail 1,000 feet below the other aircraft to see if the stories of wake turbulence were true. We were empty and well strapped in in anticipation of the turbulence so were in an ideal position to get some useful data.

After some 20 to 25 minutes when the other aircraft was 18 or 19 miles ahead on TCAS, we hit very severe turbulence and had to offset. I realise that on the fixed track structure of the Atlantic it is easier to predict the turbulence and offset; but in Europe, where the tracks are much more random and criss-cross over each other, I believe the problems will very quickly manifest themselves to all but the heaviest aircraft.

What was surprising to me was the length of time that the turbulence persisted and the fact that, in my case, the turbulence was so severe, bearing in mind the time lapse and the distance we were travelling behind the offend-ing aircraft.

It may be that the controlling authorities will have to retain the 2,000 feet separation minimum below aircraft that have known adverse wake characteristics. Perhaps restricting them to the lower levels in the RVSM structure would be a solution.

That solution may not be accepted readily by the operators of heavy aircraft but they are the offenders both in the upper airspace and at the lower levels in the take off and landing phase of flight and for too long the smaller aircraft have been penalised for the sins of these large aircraft.

Finally, whilst all users are anxious to maximise the use of all available airspace I do not believe that the authorities have done enough to investigate the effects of wake turbulence on aerospace users.

John Barry, Chief pilot at Motorola