Originally Posted by
Stranger
Normally that message is already shown on aircanada.com before you actually select the segment though. I have not seen a case where this message shows if P is indeed available. Also, when that happens the leg is normally in Y, and may be upgradeable using Aeroplan miles as long as not booked as a codeshare. The issue of P availability may be obe of these "married segment" crap. Which somehow sometimes an agent might be able to overrule, although lasy time I encountered a situation where P was available for each leg but not on the entire itinerary the agent and even the fare desk could do nothing.
P fares tend to book Y segments in M, not Y. I've encountered it a lot during EYW. It's actually a bit annoying. Something like YYC-YWG-YQR gives you the full J experience on the first leg, zone 1 boarding (due to the P fare basis) on the second leg, but you don't even get LT07 because you're in M. Unless they fixed that after I wrote in about it. Haven't tested this in a year.
But yeah, my only guess is that P was not available at time of booking, but it was when the call was made. Or AC's booking engine is dumb.