But then nothing in the FARs – AFAIK – defines their use of the term “instrument rating” as an ICAO IR
Of course not, but when, in the international context, something is written about an “instrument rating”, it is of course intended as “ICAO-compliant instrument rating”. No need to specify that.
Just to liven up the debate, I have just received this from a pilot-lawyer who wishes to remain anonymous. I know him well and he knows exactly what the issues are.
As they say… discuss 
Of course not, but when, in the international context, something is written about an “instrument rating”, it is of course intended as “ICAO-compliant instrument rating”. No need to specify that.
I would not necessarily agree. Everything not expressly prohibited is 100% legal (public policy etc matters aside) so if you want to prohibit the use of a sub ICAO “instrument rating” where the words “instrument rating” are written, you are going to have fun…
The UK, where the sub-ICAO IMCR is obviously well known, drafts the regs (the ANO) in terms like “an instrument rating issued in accordance with Schedule XYZ” or similar forms of words.
§61.3 Requirement for certificates, ratings, and authorizations.
(a) Required pilot certificate for operating a civil aircraft of the United States. No person may serve as a required pilot flight crewmember of a civil aircraft of the United States, unless that person:
(1) Has in the person’s physical possession or readily accessible in the aircraft when exercising the privileges of that pilot certificate or authorization—
(i) A pilot certificate issued under this part and in accordance with §61.19;………..
__ or__
(v) When operating an aircraft within a foreign country, a pilot license issued by that country may be used.
That seems to be a simple statement (on the basis of this, operating in UK it is OK to use a UK issued licence).
But perhaps there is guidance that those who know better have received that clarifies the situation and perhaps it is indeed not correct to fly IFR with anything other than an FAA/IR.
If it were Illegal, then under what legislation? If you can’t quote a specific regulation then it is not illegal.
If it were Illegal, then under what legislation? If you can’t quote a specific regulation then it is not illegal.
The legislation in question is FAR 61.3(e) which says you need an instrument rating on your “pilot certificate”. Unless you have a “pilot certificate” (i.e. a pilot licence issued by the FAA) then you cannot possibly have an instrument rating on such a certificate.
There is a more sophisticated argument (which I don’t agree with but what do I know?) that the State of Registry regs are not necessarily applicable if they are more restrictive than the regs of the airspace owner. We are always told that the most restrictive regs are what applies but I have a suspicion that is not the case in some scenarios. There are many scenarios which are not enforced and one wonders why… it could be that nobody wants to go there.
(v) When operating an aircraft within a foreign country, a pilot license issued by that country may be used.
Therefore; a UK licence with an IMC rating is perfectly legal. FARs does not impopse any limitations on what type of licence is used other than that it is valid in the Stae where it was issued. It does not specify an ICAO licence as the privileges are confined to the State of issue, so whether or not the licence complies with Annex 1 is of no relevance.
the State of Registry regs are not necessarily applicable if they are more restrictive than the regs of the airspace owner
The State of registry regulations apply wherever the aircraft may be, the aircraft is effectively a little bit of the mother State
