HQ is not trying to capture the YYC-YVR market. HQ has made a commitment to enter that market to provide feed to YVR for SE Asia flights, including code shares and, ultimately, future flights on HQ's own metal.

There are a whole schwack of AC flights ex. YVR to YYC around Noon onwards that are 50% or more SE Asian connex. So many in fact that the gate is often 'co-manned' with a supplemental langauge speaker due to the high number of non-english speaking through pax.

Flying the HQ metal 757's on the YYC-YVR shuttle 3 times a day for what is primarily going to be feeder traffic is not efficient, hence the CRJ's.