An American Airlines Boeing 767-300 aircraft takes off from Zurich Airport January 9, 2018.
The agreement is meant to reduce the number of passengers stuck in airports because the original carrier was unable to rebook them on a flight of its own.
“It’s a tool that will give our employees more options to reacommodate customers whose Delta flights are canceled during weather and other uncommon scenarios,” Delta spokesman Morgan Durrant said.
American Airlines spokesman Matt Miller said the carrier was happy to put the deal in place after Delta reached out several months ago to discuss the return of such an agreement between the two parties.
Neither Delta nor American detailed the financial specifics of the agreement.
Prior to its dissolution in September 2015, the two largest U.S. airlines by passenger traffic had a far more comprehensive interline agreement, which among other things allowed for booked travel to include segments operated individually by both Delta and American on the same ticket.
Interline agreements are a common industry practice, though Delta and American have declined to call their pact an interline deal.
The deal went into effect on Wednesday.