Just watched the BBC evening news here in the UK and a possible cause being cited is conflicts between ATC and TCAS.The report said that both planes were equipped with TCAS.ATC requested the TU-154 to descend but there was no response. ATC again requested TU-154 to descend and it then did so. Evidently the crash happened because both planes descended into each other.A contibutor said that the TU TCAS would be telling the pilot to climb to avoid collision with the 737 but ATC were telling him to descend which may have led to confusion and/or hesitation.The 737 TCAS would have been telling the pilot to descend which he did, straight into the path of the 737 at FL353.I do not know how the TCAS decides what avoiding action to take, what casues one to demand 'descend' and the other 'climb'.My heart goes out to all those involved, the grieving families of the those children, the familes of the two crews, the airline staff, ATC staff and those on the ground.At least no one on the ground was injured.Although tragic, thankfully a rare accident.

Update.From a news report here in the UK it looks as if the finger is pointed at Swiss ATC for only giving the TU captain 50 seconds warning and he complied at the second request.It also states that only one controller was on duty at the time.A Swiss aviation expert is quoted as saying ATC could predict 15 minutes ahead what altitude the planes would be at.

Flying as much as, and sometimes even more than, people liek yourself, i.e. airline pilots, I have quite often seen (or felt) things that I thought were not in order.... Like another jet passing right under us on opposite course.... so close by that I could read the registration.... :-eek , strange overshoots at landing, funny evasive manoeuvres at places I KNOW we should just head straight on under normal circumstances.Sometimes it is good NOT to know all that is happening, I guess. However, I am a 'driver' and would rather be sitting in front and KNOW what hit us in case it ever happened, like in my car. :-(I do think there are more and more incidents, also judging from several 'sources' that track these incidents. Not a good thing really, especially considering all the technological advances we are making. If the TCAS actually sends you straight into the other plane (as seems to have happened over the Bodensee), then what good is all our technology !!?? :-outta Francois :-wave________________________Francois A. "Navman" DumasAssociate Editor &Forums AdministratorAVSIM Online!email: [email protected]________________________

as I understand from various sources, the Tupolev descended on ATC request and only the DHL one on TCAS indication.So - it appears TCAS is not to blame here. If I understand correctly, if TCAS and ATC issue conflicting instructions, TCAS is to be followed (can anyone confirm?). It's a guess, but should that have been done the accident might have been avoided.Another sad day indeed.Vince

The latest, says that the "TCAS"(Not sure what called) for the Swiss Controlers was in the OFF mode, for maintenace. Yes I heard too, that the 154 decended on ATC command,(which was like the 2nd 3rd try though) and the 757 decended on TCAS command.Jeff "Ace" Frey:-outta

Don't blame too early good ald TU 154 :-)It now appears that the Swiss ATC is being pointed for fault. Minos

I believe TCAS is a requirement in European airspace for all big iron.I also beleive that TCAS equiped planes interrogate each other when they detect a possible collision and decide on which plane goes up and which goes down. Kind of like a modem handshake.Would be very suprised if it was equipment failure and not human error.Eric ThorntonSingapore VAhttp://www.cpavirtual.org/images/sqbanner2.jpgwww.flysva.orgJAL VAhttp://www.cpavirtual.org/JAL/images/JALbanner3.jpghttp://JAL.virtualATP.org

I saw an animation on CNN. It as actually just a single still image. I was created using 3D modeling software. Not FS. I'm sure we will see 3D animation made from 3D animation programs used for accident investigation but never a game.Pete

a Airline reporter specialist on CNN said that TCAS between different planes do not communicate with each other. ONly communicates it to its pilot of its own self. But did say perhaps if they did this might not have happened. But, you can bet that since mid air is so rare that no such improvemets will be made. At least thats what I feel.Pete J.>I believe TCAS is a requirement in European airspace for all >big iron. >>I also beleive that TCAS equiped planes interrogate each >other when they detect a possible collision and decide on >which plane goes up and which goes down. Kind of like a >modem handshake.