roncachamp
Final Approach
I would define a GPS IFR routing as a routing which requires RNAV to accomplish. It certainly seems like a GPS DIRECT off-airway route between two fixes would qualify.
When you receive such a clearance, does the controller say "GPS direct", or just "direct"?
There is nothing to indicate to me as the pilot that there is no radar coverage on a portion of that route. Since there is nothing to indicate it I file direct. I'm cleared direct. At some point I drop off radar and that is how they choose to handle it. It seems like radar coverage is particurally weak around Pocahontas. I'd guess there is at least 20 miles of no coverage - maybe even more like 40.
I've found radar coverage to be particularly weak in the northwest Iowa area. There are certainly aircraft flying off-airway via RNAV outside of radar coverage from time to time in this region.
Back to my original question, what is the source?
The source is Order JO 7110.65T Air Traffic Control, see paras 4-1-1 and 4-1-2.