Originally Posted by
qraec777
Update : Recently transferred from BA to WS via YVR, and I was pleasantly surprised to find that BA to WS connections are now covered under OSS. I didn’t have to collect my bags at YVR, and the entire transfer process was smooth and easy compared to my previous trip. I didn't have to clear security to get on my next flight either. Just to note, this applies only to BA to WS connections. BA to AC connections still require you to collect your bags at YVR.
Excellent news, though it does seem a little confusing. I'm not sure why BA-to-AC connections aren't covered at YVR (or YUL, presumably). YYZ makes sense because they are in two different terminals, but in YVR obviously BA and AC are co-located. BA is no longer a codeshare partner of WS, so they have only an interline partnership just like BA and AC have. It makes little sense, therefore, why domestic connections to WS have automatic baggage transfer and to AC they don't.
All arrivals from the UK into Canada, when automatic baggage transfer takes place, qualify for One-Stop Security. Canada unilaterally recognizes UK security screening (although the UK doesn't recognize Canada's and requires onward passengers at UK airports to be rescreened). When we connected at YUL a couple of months ago from LGW on Air Transat to Porter (domestic), we didn't have undergo security screening.