Delta Air Lines (DL, Atlanta Hartsfield Jackson) has announced that it will discontinue an existing interline ticketing and baggage agreement with American Airlines (AA, Dallas/Fort Worth) effective Tuesday, September 15. The agreement provided, among other things, the ability for carriers to rebook their own customers on other airlines during irregular operations (IROPs). Interline agreements have long been an industry practice to help carriers support passengers during IROPs. These work through a standard rate that carriers agree to pay one another.

“Unfortunately, we couldn’t reach an agreement with American that adequately addressed the number of IROPs customers that American transferred to us,” Eric Phillips, Senior Vice President – Revenue Management Delta, said. “In July, for example, American sent passengers to Delta for reaccommodation at a five-to-one ratio. At that rate the industry agreement was no longer mutually beneficial.”

The cancellation of the interline agreement with American also means that travel booked (primarily through travel agencies) on and after September 15 can no longer include segments operated by Delta and American on the same ticket. Baggage transfers also won’t be accepted between the two carriers.

Delta said that all ticket and baggage exchanges issued prior to September 15 will be honoured.