Gerard M Foley wrote: > Further questions about this collision include asking why the two aircraft > were cleared into the same airspace at the same altitude at the same time, > apparently by ATC's of two different nationalities, Italian and > some other. > As has been said, TCAS is not supposed to be the first line of defense > against collision. This is like asking why an aircraft approaching US airspace from Mexico and one heading south from Canada is allowed to be at the same level, although admittedly the scale is somewhat smaller! The two controllers handing over the traffic to the Zurich center might not even had known about the other traffic. Their aircraft are entering another sector (and in this case the airspace of another country, but that's really not important in this scenario - it might as well have been two adjacent sectors within the same Area Control Center) and the person responsible for solving conflicts within this sector is the controller working this position. Strips or electronic devices with the same function are normally used to detect these kinds of conflicts well ahead of time and in a normal scenario, the controller working the sector would call the previous controller asking to have one of the aircraft delivered at another level. Obviously this did not happen in this case, but perhaps the inevstigation will reveal that he had tried that prior to getting occupied with the phone calls to Friedrichshafen airport, and perhaps also had failed getting in touch with his colleagues in Germany or Italy? Perhaps he then decided to solve the conflict himself once traffic was on his frequency, only to forget about it when the problems of giving an inbound release to Friedrichshafen stole his attention. This is of course pure speculatioon, as no details of his work in the minutes prior to the mid-air has been released. But in short: The 'problem' you're raising here is really non-existant, as any controller or other person with knowledge of the ATC system would tell you. Nevertheless, it's the sort of 'problem' the general media would like to do a story about, as it sounds really reckless when presented thsi way, although it's really perfectly safe when the ATC system works like it's designed to. Of course the safety of the system could be increased by applying the 'one flightlevel - one aircraft' principle. That would mean that approx. 30 aircraft could be flying in US airspace simultaneously - 8 of them within the preferred level bands. The rest would have to stay on the ground until there was a free level for them. So let's stick to the 'one flightlevel - multiple aircraft separated by at least 5 nautical miles' principle, shall we? Rgds Jan Broe EKCH ATC