"JJ" wrote...
When commercial aircraft fly across the big pond during IFR weather, how
does FAA and foreign Air Traffic control keep an eye on them without
radar? I understand most flights to and from Europe go up over
Newfoundland and over south of Greenland and Iceland. Can a radar see
out that far?

Most trips will be out of radar coverage for at least a couple hours. Those
that go over or near Iceland will have more coverage.

However, traffic separation is based on specific Oceanic Clearances based on
specific departure times from near-land fixes, altitude, a system of specific
"Tracks" (routes) during the "rush hours," controlled airspeeds, and position
reports from the airplanes via HF or VHF radio every 10 degrees of longitude.

Radar coverage is not required. Trips across the Pacific go much longer without
ATC radar coverage.