This illustrates why the issuers do this rather than simply lowering the annual fee...
You are counting the same $300 twice. Once to reduce the annual fee, and again to claim that you are receiving a free month's hangar rent. It's one or the other, but not both.
Indeed. I will have to keep reminding myself--next month when I have to shell out $450--that I already got my credit 8 months ago, and that another one will be coming in January.