CPDLC AND RE-estimates.

[Willit Run]

My company put us through a very basic CPDLC course.
Our instructors think that if the position of the next fix is off by more than 3 minutes from your initial estimate, that we are still required to give and update before ten minutes prior to crossing said fix. Is that true considering ATC is getting constant updates from ADS-C ? They know everything about us.

I'm just trying to get a grasp on this as it seems DC-8 procedures are being dragged into the future.

Appreciate any help you can throw my way.

Thanks

[safelife]

Yes and no, the problem first of all is that you won't really know which estimate had been reported by CPDLC. Most probably the estimate shown by the FMS at the time the Waypoint was sequenced.
But depending on the CPDLC contact the position (and the estimate) will be sent not only at each waypoint, but also at a certain interval, like 18 minutes or so. That will take care of the reestimates.
Btw. it's 3 minutes, or more, not, more than 3 minutes. A mismatch of 3 minutes already requires a reestimate.

[safelife]

Some more intel here:

http://www.pprune.org/atc-issues/475538-ads-cpdlc.html