Quick CPDLC Question

[germb747]

Here's a quick CPDLC question; I tried a search but couldn't find the answer.

I've only flown 5 trips with CPDLC, so I'm pretty new at it (actually, so is everyone I'm flying with!) Over the NATs, I've been either sending ATC text messages or calling in on HF with revised estimates whenever my position estimate changes by 3 minutes or more. The question came up as to whether or not this is actually required, since I'm using CPDLC with ADS-B. I couldn't find a clear answer in the MNPS manual. Thanks to anyone who might know the answer.

 

[derg]

Any ETA that is off by 3 minutes is considered gross navigational error which must be reported.

Sometimes mid-leg the ETA may fluctuate depending on if you have accurate estimated winds in the FMS so sometimes it might "tickle" the 3 minute mark, but generally it'll trend back towards the ETA.

Some of our 757's that still have the original former TWA-AA "OMG I can't believe they expect us to fly over the ocean with this damned archaic" FMS have terrible ETA computations, but the newer Pegasus and DL3 boxes are pretty much spot-on. Well, I guess you really didn't ask me ALL of this!

 

[germb747]

okay, thanks Doug. I just wasn't sure whether or not the CPDLC/ADS took care of that task for me or if I still had to revise the estimate myself. Our new FMS does beat the hell out of our old FMS 800s, but we did end up with the wicked winds in our face crossing the NAT a few days ago. Thanks again.

 

[staplegun]

ADS-B reports your position every second or so, but I think (I could be wrong!) that the Oceanic centers only receive the reports from over your route waypoints, hence the requirement to update with ATC if the time is off by more than 3 minutes.

Kevin