Unfortunately there is no such thing as a plain English initiative by the CAA so you have to read and interpret.....Unlike the FAA who have a very nice plain English Q&A on the FARs.
The ANO [Part 4 Article 21 paragraph 4] states [in plain English] that a licence issued by an ICAO state can be used in the UK in a G reg aircraft at Private level only. It does not restrict you to Day or VFR flight and ANO Aritcle 21 [4] does not prohibit exercising the privileges of your ICAO ratings [ie. Multi / IR] while in command of a G reg aircraft either. However there is an exception stating that you are not allowed to fly in controlled airspace in a circustance where you must comply with IFR - instrument flight rules [to avoid confusion]. Situations where you would have to comply with IFR [rules] would be if you were in IMC [conditions], or on an IFR flight plan [However you'd be on an IFR flight plan while in IMC in CAS anyway]. So lets call it on an IFR flight plan in CAS regardless of the conditions of flight.I am not sure on Night flying in CAS as I haven't researched it [this is technically IFR].
However ! Outside CAS, whether day or night you are entitled to fly in accordance with IFR does mean that you no longer need to be 'in sight of the surface' or in VMC [visual met conditions] and you can be on an IFR flight plan if you wish. In the UK there is no requirement to be on an IFR flight plan whilst in IMC while outside CAS. This also applies in France and Germany as they accept 'whatever the CAA accept'.
A vanilla JAA PPL must fly 'in sight of the surface' at all times, whether in or out of CAS which clearly rules out VFR-ontop or flight in IMC conditions.
So in theory an FAA certified pilot who holds FAA ME/IR wishing to fly from Bournemouth to L2K in a ME aircraft could file a composite flight plan, leaving under VFR, transfering to IFR outside CAS, then transfering back to VFR before entering French CAS.
Hope this clarifies the quagmire a bit!
EA
