CoolIP,
I  need to DME update in first 150 nm of my flight. Some updates either I missed or just let it go. Numbers increases to 9.4, BUT no warnings or alerts appears, INS continue to work with out any problems. FD controls the HDG and INS controls the position/legs and coordinate checks/navigation. In my last flight , when first 150 nm update required and I didn't update.   CYYR (Goose Bay) to THXF (Bermuda) INS and FD worked perfect and reached the destination with out any navigational errors. :o
How INS continue function with out DME update? :-?

Sanal