Accusers round on Swiss air controller

After a day scrambling for excuses and revising figures, Swiss air traffic control officials tonight conceded that they told the pilot of a Russian charter jet to reduce altitude and avert a mid-air collision less than one minute before it smashed into an oncoming cargo plane.

The two planes both were making a fatal descent from 36,000 feet to 35,000 feet when the accident happened the Russian plane in response to urgent orders from Swiss air traffic control and the cargo plane in response to its on-board collision avoidance system.

Skyguide, the Swiss air traffic control body, initially insisted that it had given the Russian crew between 90 seconds’ and two minutes’ warning to descend and that the crew had only begun the descent on the third request.

But, after a late afternoon press conference, Skyguide officials were forced to confirm what German authorities were saying: that there was only 50 seconds’ warning and that the Russian plane complied with instructions on the second request.

‘‘Skyguide still believes that the warning was tight but sufficient,’’ said spokesman Urs Ryf.

‘‘It’s up to the investigation to reveal everything else,’’ he said.

Anton Maag, head of the control tower at Zurich airport, earlier described the margin as ‘‘not irresponsible but it was fairly tight.’’

The planes collided at a height of some 36,000 feet while they were flying through air space which technically belongs to Germany but is the responsibility of Swiss air traffic control as it is on the direct approach to Zurich airport.

Russian officials were quick to dismiss any suggestion of pilot error or problems due to poor English language skills and laid the blame firmly on Europe’s fragmented system of air traffic control.

Skyguide spokesman Patrick Heeb compared the air traffic system to a relay team between national authorities.

But there were growing indications that the Swiss may have dropped the baton.

Swiss air traffic controllers took over responsibility for the cargo plane at about 10.23pm Irish time and for the Russian plane at about 10.30pm Irish time.

The accident occurred at 10.35pm Irish time, when just one air traffic controller was on duty in Zurich because his colleague was on a break.

The controller, described as an experienced member of staff, was being treated for shock today and had not been questioned.

Sepp Moser, one of Switzerland’s best known aviation experts, criticised the Swiss for reacting too late, given that they could predict at what altitude the two planes would be flying 15 minutes beforehand.

‘‘I think that the behaviour of Swiss air traffic authorities should be examined on a second-by-second basis,’’ he said.

‘‘Without a doubt, the Russian pilots responded late but they responded late to a late warning, and that is the essence of the problem.’’