Originally Posted by
Seattlenerd
Minor data point: P does still exist for those who haven't spotted one lately. I have a P fare (discount First) coming back from SAN to SEA in April that I purchased directly earlier this year. Shows as "Class: P (First)" on the email receipt.
Actually, all the discount/restricted AS FC fares still appear to book into P booking class. Presumably, they are adding the I booking class to give them somewhat finer-grained control on FC availability. For example, DL restricted FC fares book into one of 4 different booking classes (C/D/I/Z).