Does anyone know if the "LAST POSITION" on the FMC POS INIT page updates on the real aircraft as the flight progresses?I suspect it does.Also, I've noticed on 747-400's that the LAST POSITION does not freeze when the IRS's are turned off, if the GPS's are still inputting into the FMC. Even when the aircraft is being towed (with the IRS's off, but with aircraft electrical power on), the LAST POSITION is constantly being updated. On non-GPS aircraft, I believe the position freezes (although I'm not sure at what point... perhaps IRS shutdown, perhaps park brake set/fuel levers off?).Something to consider when implementing a full IRS system ;-)Cheers.Ian.

Tried any ocean routes yet with no VOR updates to the IRS systems? Do you get a FMC message as you would in the 744 or do the systems get GPS feeds still and not care about loss of radio updates since the GPS makes up for it?No idea how the 737 systems glue together for navigation, looking forward to the arrival of Bill's FMC NG & Cockpit NG guides to be able to actually learn some 737 specific stuff. Good thing a lot of this is common across big aircraft.Ray

"Tried any ocean routes yet with no VOR updates to the IRS systems? Do you get a FMC message as you would in the 744 or do the systems get GPS feeds still and not care about loss of radio updates since the GPS makes up for it?"The (real) 747-400 treats the GPS as a Radio Update (so no "IRS ONLY" messages in the middle of the ocean). I'd say the 737 would be similar (PMDG's NG models GPS... or so the POS INIT pages seem to indicate).Cheers.Ian.