Originally Posted by
Kiwi Flyer
If D is not available it books into L (cheap economy booking class), with the main exception for AA 2-class north america flights which book into A (discounted first), and a few specific exceptions (eg certain airlines with 1 class, or where the highest class is premium economy). ...
If an AeAgle flight (AA3000-AA5599) then A/DONEx's book into Y class.