Originally Posted by
gateguard0
I tried unsuccessfully to find YYZ-IST-CDG routings in a one-way Aeroplan search.
I then used the multi-city search to force an IST connection -- that is, searching YYZ-IST on Day 1, IST-CDG on Day 2 (looking for < 24 hour connections), CDG-YYZ as a dummy return in the future just to get the multi-city search to validate. After selecting the YYZ-IST direct flight, any IST-CDG option with a connection time < 24 hours was greyed out. It only allowed connections > 24 hours, turning the award into Europe 2 with IST as the destination.
Point is that YYZ-IST-CDG does not appear to be a valid routing. For what it's worth, YUL-IST-CDG results are similar.
My guess would be that IST can be included in some [NA Non-Hub --> IST --> Europe 1 Non-Hub] routings, but most [NA Hub --> IST --> Europe 1 Hub] routings don't work anymore. I'd be happy to be wrong though...
I'm not quite sure what was going on in your search, but I just ran the same search (YYZ-IST, IST-CDG, CDG-YYZ), and I had no problems getting options for all 3. And just to further emphasize the point, the random date I selected had no availability on the YYZ-IST TK flight, nor on any non-stop CDG-YYZ, so my final test itinerary ended up being YYZ-FRA-IST-CDG-YUL-YHZ-YYZ, which really pushes the limits of allowable mileage.
As another data point, I have YQB-YUL-IST-BCN booked for next summer, and have frequently seen YUL-IST-BRU offered by Aeroplan.ca, so I think either it's a glitch or your arrival/departure times on the connection didn't line up.