This is correct. Our 737 will have only one FMS, just like most of the Classic 737´s out there. So it´s just one computer connected to two control-display-units (CDU´s). If the one FMS fails, you loose it all. Therefore this (our) model would not be allowed to fly in the North Atlantic MNPS airspace. That being said, I can guarantee that our FMS will not fail on you during the transatlantic flight, and I will not rat on you for taking the trip with just one FMS, either. If you want to take the trip "full realism" you have to take the detour out of MNPS airspace, maybe top off the fuel in Keflavik, then over to Iqaluit or Gander. Depending on the headwinds... The challenge is actually in getting this setup working. You can enter stuff on two different "keyboards", but need to keep tabs on each one, update information on both...its not trivial. You can have the LEGS page on both CDU´s, and both pilots *could* be editing away, that stuff makes a programmer drink too much coffee... Having two or more FMS computers is easy. You just say "we have 5 FMS computers". Thats it. They all share and sync information (kinda like a raid 1 harddisk system). All computers have the same information. Unless all 5 fail, nothing happens (except for the error message that they failed). Jan