DrunkCargo

I'd just sit on the floor or in the chairs behind the gate monitors (D22 has these), maybe surrounded by wheelchairs and other random gate equipment, wait for crew to leave in a hurry given flight was 31m delayed, GA still at the counter doing closing tasks on terminal possibly chatting with crew. It would be a matter of calmly standing and walk down the bridge. 4 meters down I'm out of line of sight from where the GA might shoulder-check if s/he was at the left terminal. GA follows after I've started farting in J seats, closes plane door, closes bottom of bridge door, pull bridge back for tow, then closes top of bridge door before leaving gate. I don't see any inbound/outbound after at D22. My guess is that the crew departing plane are either supposed to close top of bridge door after leaving, or ensure GA is attentive to the gate door. Honestly, thinking about YYZ D22 it seems like this would be quite easy to pull off. But why?

Groomers are likely brought onboard before next first flight for that fin (AC1790 at gate D33), after AC employed crew have turned lights on and are present to handle possible emergency egress at gate. Waste of money having groomers wait around for potentially delayed flights to clean a plane that might be rescheduled to not operate for days, and good luck getting crew to babysit cleaners off block time. Ramp staff would have no reason to enter plane, guessing brakes aren't needed assuming ground crew put chocks around landing gear.

My experience boarding planes (with GA permission, not AC) after crew have left is that it is shut down entirely; my memory was that it was boiling hot onboard and terminal lights provided enough light to retrieve items left behind. Crew absolutely didn't have any desire to stick around for some stupid F pax hunting for wallet, phone, etc... that would be the plausible excuse if caught in bridge: "Ooops, I left my <insert embarrassing yet plausible item here> onboard. Please help?"