A followup to this question:
I have booked an itinerary on Turkish Airways travelling from outside the EU to the EU via Istanbul, consisting of four flights, all on the same PNR.
If I'm parsing my Air passenger rights page right, since TK is a non-EU carrier, the only flight out of these four where EC/261 compensation rules apply is flight #3 ("your flight departs from the EU to a non-EU country operated by an EU or a non-EU airline"). A non-official site also states that:
In some cases, disrupted flights outside the EU may be eligible under EC261 if they connect to a covered flight that is with the same carrier and part of the same flight reservation (under one booking reference number).
But does not explain what these "some cases" are, much less point to an authoritative source.
In my case, TK has cancelled flight #1, effectively invalidating the entire itinerary. If TK does not notify me of flight #1's cancellation in time (at least 14 days), am I entitled to the EU compensation for flight #3?
Note that this is not a directly connecting flight, so I presume the answer is "no", but it would be nice to find an authoritative source.