Quickie regarding waitlist
 

Didn't find an answer when I searched this forum but I'm curious so I'll put it out there to the gurus.

I realize that being waitlisted is based on the surface on availability...but what else is it based on?

I usually upgrade at the minute I can, so last night YVR-YYZ, lots of space, no issues got it right away. This morning I had my alarm set to upgrade YYZ-MIA...I didn't figure in the time difference!!! So I was late by 2 hours. Waiiitttt Listtttttt :(. But checking the seat map I noticed 5 of 8 J seats are still open and I thought they'd at least auto upgrade to 50% of capacity no?

I've only ever failed one other time when jumping on the opening window of upgrade which was last week YVR-YEG I immediately got waitlisted, then at the gate got it anyway, so fingers are crossed for MIA (since it isn't charging me any extra credits) but I'm wondering if there's a magic algorithm or certain routes, or any light to be shed on when you get waitlisted.

As you said, it's all about availability - but for an instant upgrade, the availability is for 'R' class, not the number of J seats still available. The number of R "fares" made available can therefore be adjusted by the AC revenue management folk; if they expect that J will sell out on any particular flight, they may not make any R available at all.

Case in point, I'm flying HKG-YYZ on Monday, and the J cabin was wide open; J9 and the seat map looked like there were over 30 seats still open... But there was no R availability so I went onto the waitlist.

The upgrade can then clear at any point, in advance or just at the airport... But it's under AC's control - it all comes down to revenue management.

You can see the R availability in most of the online tools (expertflyer is my preferred tool) and if a flight shows R>0 then an upgrade request will clear right away.

Thanks, that's helpful, I had the expertflyer membership for a bit but wasn't really using it so I scrapped it. I figured it was something like this but I wondered if there might be an actual formula someone knew. It's funny though in the times I have been waitlisted I've never been upgraded via email, I've heard of it happening but mine have always been at the gate.

All the rules are here
 

Experflyer, kvs or flightstats will tell you how many J seats are left; not the seat map. Seat map means nothing ever.

Many people buy tickets and don't select a seat; a map that shows 5 open seats could have 5,4,3,2,1,0 seats actually left.