Fare class Y is used during re-booking due to IRROPS. Mileage earning is based on the ticket (paid) fare class and NOT the rebooked fare class.
Fare class ranking
Higher Fare Classes
Y – IRROPS (Silver), Y – IRROPS (Gold), Y – IRROPS (Platinum), Y – IRROPS (Diamond)
Lower Fare Classes
All IRROPS upgrades happen ahead of non-IRROPS passengers. Upgrade probability is based on fare class ranking and medallion status. These calculations are estimates only and should be used as a general idea of ranking for upgrades at the gate. All complimentary upgrades are based upon inventory availability.
These calculations are not endorsed or provided by Delta Airlines.