Join Date: Sep 2000
Location: Saginaw, MI (MBS)
Programs: UA 1K 2MM, Marriott Titanium w/Lifetime Plat, Hilton LIfetime ♢, National Exec, Amex Plat
Posts: 5,750
If it's Air Canada metal, it's only a 2-class flight--they do not offer an international first class product. Also note that GPUs cannot be used on Air Canada.
You should be able to call Air Canada to get seat assignments...And perhaps do through their website if you have the AC confirmation number--should be listed at the top of your itinerary when viewing it on united.com.