Fears over mid-air safety rules

71 people - including 52 children - died in the crash

By Tom Housden BBC News Online

Thousands of airline passengers may be at risk every year because of differing interpretations of safety rules.

The investigation into last week's fatal mid-air collision over southern Germany has revealed that Russian and European pilots follow different procedures when responding to the warnings from their on-board Traffic Control Avoidance System (TCAS).

Aviation authorities in Europe say the general rule is to advise pilots to follow their TCAS at all times, even if its warnings conflict with air traffic control orders.

But Russian air officials say their pilots are trained to take account of both before deciding themselves what course of action to follow.

	:	Mid-air collision
How the crash happened

There are no internationally accepted regulations governing mid-air safety warnings.

Preliminary findings suggest that the pilot of the Bashkirian Airlines Tupolev 154 ignored TCAS warnings to climb, instead obeying last minute orders from air traffic control to dive.

Fatally this put the plane on a collision course with a DHL Boeing 757, the pilot of which was following a "descend" instruction from his TCAS machine.

But a poll taken of European pilots by the authoritative Flight International magazine reveals that an overwhelming majority said they would have reacted in exactly the same way as the Russian aircrew.

Pilots are trained to follow TCAS, but there's not enough emphasis on what to when you have a conflict

David Learmount, Flight International

Flight International's David Learmount told BBC News Online: "These Russian pilots would have heard a warning from their TCAS, but within seconds received not one but two urgent opposite instructions from air traffic control.

"In our survey every single pilot said they would have done the same, apart from one who said 'I don't know what I would have done'. In that situation, abstention is no good."

Not enough training

Mr Learmount said that he believed pilots do not receive enough training on what to do in situations when they receive contradictory instructions:

"Pilots are trained to follow TCAS, but there's not enough emphasis on what to when you have a conflict, he said.

"The trainers just hadn't foreseen this situation, where pilots start to follow the system, but within seconds receive warnings from the ground not just to take evasive action, but to do so urgently"

"With TCAS, like all pieces of kit, there's always something you hadn't thought of."