"Julian Scarfe" wrote in message
...

So is there some sort of generic authorization, or is it authorized on a
case by case basis?


Probably neither.



The latter seems unlikely. Do you really apply for such an authorization
every time you fly IFR to Canada?


I've never flown IFR to Canada. Given that Part 91 only prescribes rules
governing the operation of aircraft within the United States, including the
waters within 3 nautical miles of the U.S. coast, I'd feel pretty silly
asking for such authorization if I had a notion to.