While over non-radar controlled airspace (e.g. the North Atlantic, the Pacific, or over vast parts of Africa), pilots will submit position reports. Is there a regular time interval in between position reports, or is that only dependent on reaching a waypoint in the flight plan? What happens then, if waypoints are hundreds of miles apart (which would be the case for example over northern Canada)?
Can the position reports be also submitted via CPDLC (Controller-Pilot Data Link Communication)?
It's not fixed. I checked ICAO Annex 10 Vol II that lists the SARPs for communication. It will be down to the FIR the flight is being conducted in. For the NATS (UK) side of the Atlantic, I found this document (may not be current).
The basic intervals are whichever comes first:
CPDLC is used, and can be automated too (ADS-C). If the FIR does not support CPDLC, then it will be via voice. According to Boeing, FANS 1—which handles reporting via datalink—saves a lot of time and improves accuracy:
The uncertainties of traditional voice position reporting and the delay associated with high-frequency relayed voice communications [result in 20 to 45 min to make a position report].
And depending on the ADS-C (C for Contract) agreement, the reports can be as frequent as every 5 minutes.
For the US side of things, check section 5-3-2 of the AIM and the section titled additional reports. It's similar to the above. They also note:
For aircraft providing automatic position reporting via an Automatic Dependent Surveillance-Contract (ADS-C) logon, pilots should discontinue voice position reports.
It depends on the type of flight rules you are conducting the trip accordingly. In the United States, the FAA requires pilots to make position reports on IFR flights in controlled airspace where radar coverage does not exist. When your flight plan is activated and opened by means of receiving an IFR clearance, ATC has cleared a block of airspace along your route between your clearance time and your estimated time of arrival at your destination. Since they may not be able to follow your flight over certain segments due to a lack of radar coverage, the need to know when you have arrived at your planned waypoints and rely on your periodic updates when you reach them during your flight; if you don’t report in at these specific points within a reasonable time window, ATC may assume that something has happened to your flight and initiate search and rescue operations.
Near as I know, position reports are still done by means of VHF radio communication; they cannot be submitted to ATC by other means.
