I've not been able to detect any logic behind the problems with the "View Booking" tool. For example, I made a reservation at the end of June for October travel. For the first week or so, I could not get it to show on the AC website; just the error message that they "are temporarily unable to process" my request. Then suddenly, my itinerary was displayed without a problem until this past weekend - now all I get is the same error message again as a month ago. My reservation has not changed at all since I made it, as I'm able to also check it on virtuallythere.

Maybe the problems are with bookings that were not made on aircanada.com? But it's still completely random.