Originally Posted by
lsquare
Is it possible to check online whether a booking would clear immediately online or I'll have to call in to ask? The routes that you listed are also routes that I'm interested in.
There is no way for DL customers to check for certificate upgrade inventory. You have to ask a phone or Twitter agent. And again, this question and others about usage etc are already answered in the two threads I linked to above and their wikis, so it would probably be worth your time to check them out.