In my view, TCAS is the greatest single advance in flight safety in my 20 years flying – the TCAS display featured on the reconstruction last night (B747 classic sim appeared to be standing in for the DHL B757), where traffic information appears on a VSI (Vertical Speed Indicator), is actually the least impressive presentation (a retrofit on an older aircraft).
Most modern aircraft (757/763 for example) present traffic within range (about 80 miles horizontally and +/- 2700ft vertically) on the EHSI map display, which makes it a beautifully clear presentation – TCAS escape manoeuvres are displayed on the EADI (Electronic Attitude Director Indicator), and again are very clear and easy to interpret.
The point about TCAS is that is purely an airborne device – the TCAS computers in the aircraft will communicate with each other to co-ordinate the escape manoeuvre, and it is up to the pilot to trust that totally. There is no communication from the TCAS computers to ATC, and when an aircraft is carrying out a TCAS climb/descent, ATC have effectively relinquished control. So the tragedy of the collision is that the Russians were obeying an ATC instruction, rather than following the TCAS commands.
As the programme showed, accidents are rarely due to a single event, but usually a chain of circumstances – sadly, I suspect Peter X will be presented as the scapegoat (far easier to blame a single human than admit a corporate failure)
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