Changes in Swiss story

Swiss controllers have amended their account

Within hours of the mid-air crash, Swiss air traffic control company Skyguide was publicly stating that the Russian pilot had failed to heed commands to descend.

As the hours went by, it began to emerge that the Swiss account of the minutes leading up to the crash was subtly but crucially at odds with what German investigators were to discover.

An initial press release from Germany's BFU crash investigators appeared to contradict at least two main facts.

The problem was that the Russian plane did not respond immediately

Anton Maag
Skyguide

First, the pilot's initial failure to heed instructions to descend, which was widely reported on Tuesday morning.

"The problem was that the Russian plane did not respond immediately," Skyguide official Anton Maag said.

"The descent was begun very late. The double descent led to both planes flying at the same altitude and hitting each other."

Whereas the crew did not react on the first instruction, they acted upon the second one

German investigators

The pilot started his dive only after Swiss controllers had instructed him to do so three times, Mr Maag told a news conference.

Mr Maag said it was unclear why it took so long for the jet to respond to increasingly urgent instructions.

But the German investigators reported that, from their initial assessment of taped conversations, the Russian pilot had missed only one warning and had complied with the second.

Timing row

The second key area at issue is the timing of the warnings.

Mr Maag initially told a news conference that the first warning was given one-and-a-half minutes before the crash.

This was later changed to a "good minute".

Chief pilot Alexander Gross was initially blamed by the Swiss

But the German investigators found that the first warning was given only 50 seconds before impact.

There is also controversy over whether the air traffic controller acted too late.

"The way our colleague worked was cutting it close, but absolutely acceptable," Mr Maag said.

But other air traffic controllers said longer notice could have been given. One controller said he normally aimed at separating planes at least 20 nautical miles before impact - which would have been at least double the warning time given in this case.