Hi,Just wondering, as I haven't tried this yet: If I disable the GPS equipment option, will I get IRS drift and a map shift upon re-entering radio position updating range from a long overwater leg or similar?-Shaun

>>Hi,>>Just wondering, as I haven't tried this yet: If I disable the>GPS equipment option, will I get IRS drift and a map shift>upon re-entering radio position updating range from a long>overwater leg or similar?>>>Shaun,Map shift remembers me of the old Omega systems, don't think you reference to that.Not being that, IRS's always have IRS drift, but the FMC position can be updated by radio positions where available (continents) and also by GPS (globaly).If you inhibit GPS, the overwater FMC position becomes less accurate, due IRS drift, but will correct itself (gradualy) once receiving station again over continents.Hope it answers your question.Regards,Harry

Shaun,Harry answered that. In addition, to understand how this works, go to the REF->POS REF page. You can see there the IRS drift and the calculated FMC position.

Cool, so the map shift will correct gradually on the MD-11 rather than a sudden jump when it re-enters radio updating availability? I have another add-on that makes a HUGE map shift and turn when it comes back into VOR range. Have always wondered if that was realistic.I will check out the POS REF page as well. Thanks guys!-Shaun