This is indeed a tragic accident, and but for the grace of God could have taken many, many more lives. I don’t presume to make any conclusions about this event, but there are a number of issues that we should think about in busy European RVSM airspace.
- Respond to TCAS resolution advisories in the extent to which the cues are provided on your EADI or EVSI. An RA will often require no more than 1500 fpm climb or descent to deconflict the traffic. At high Mach numbers and flown manually, the pitch change is remarkably small. A panic large input may cause additional problems or even an upset.
- Resist the temptation, especially at night, to try and second guess the TCAS RA. In RVSM, and aircraft 1000 feet below you might look as if it’s actually above and vice versa. Trust the TCAS and use it to enhance your mental model of your bit of airspace. You may think you’ve worked out the best avoidance, but the TCAS has a contract with the conflicting traffic and has worked out the best avoidance manoeuvre. Remember, the other target may be simultaneously involved in avoiding another aircraft.
- If your aircraft is fitted with an early type of display, remember that the azimuthal error in TCAS can be up to 20, which means that the intruder could be either left of the nose or right of the nose. TCAS is designed to provide only vertical deconfliction, so again don’t try to second guess it.
- Listen out on your frequency, try and plot other aircraft in your mental model, and think about where conflicts might arise. If necessary inform ATC of any concerns you have about another aircraft. They will be more than happy to put your mind at rest.
- Make sure that at least one of you is monitoring 121.5 at all times. Someone may have urgent news for you, and you may not be talking to them at the time
It is entirely possible that at least one of the aircraft involved in this did all of these things. It is tragic in the extreme. I offer these pointers not to criticise or suggest possible cause, but to reinforce good airmanship and operating practice.
Sincere condolences, and my deepest sympathy to the controller at Swiss.
