Strange coding
 

So both DL 181 and DL 1131 from LGA to DTW are flown on A319s. Yet DL 181 is coded as having Business class while DL 1131 has "First" class. It took me awhile to realize why my "low" reward was clocking in a 200k miles (LGA-DTW-HKG). Anyone able to explain how two different flights on the same airplane one has J and one has F?

Business is coded to first or last legs of a continuing international flight number. Unless you are flying JFK-LAX/SFO, you will have domestic first class service regardless of this notation.

thank you for the quick response, never occurred to me. Though I would think Delta would continue to phase out the F coding to all B/E J coding. Might help a bit with the award calendar.