Passengers flying on American Airlines who get stranded at an airport because of weather or a maintenance problem can now get a seat booked on Delta -- and vice versa.
It's all part of a new agreement that lets the airlines re-book passengers on the other carrier's flights in the event of a disruption, like a blizzard, computer outage or aircraft breakdown.
The aim is to move stranded passengers out of airports and on to their destinations as quickly as possible.
A Delta spokesman called the new agreement "a tool that will give our employees more options to reacommodate customers whose flights are canceled during weather and other uncommon scenarios when Delta flights are canceled."
An American spokesman said Delta approached the carrier about the agreement, and similarly signaled that the arrangement was another tool for its staff to help customers.
The pact took effect on January 24.
The agreement, which has been in the works for months, comes after some high-profile disruptions.
Delta's home hub at the Hartsfield-Jackson International Airport was battered with storms in April, leaving thousands of flights canceled. The carrier was again derailed in December by a power outage at the Atlanta airport, grounding flights and costing the airline as much as $50 million.
American also faced the prospect of significant disruptions late last year when a scheduling glitch inadvertently allowed too many pilots to take vacation around the Christmas holiday. American averted a crisis by offering a significant pay bump to its pilots and tapped reserve crews to fly.
The two airlines did not go so far as to restore their previous interline agreement, which they ended in 2015. That would have allowed their respective fares to be combined as part of newly booked itineraries.
Delta maintains interline agreements with more than 100 airlines around the world, including United Airlines.