Delta said it will start leasing the 717s next year as long as its pilots approve a new labor contract, which isn't certain. Also, Southwest said some of the deal's details still need to be worked out.
Delta said it will begin taking three planes a month starting in mid-2013.
With 117 seats, the 717 fills a hard-to-fit niche in Delta's fleet. Delta will use the 717s to replace 50-seat regional jets, which are increasingly unprofitable at higher fuel prices. They'll also replace the DC-9s that Delta got when it bought Northwest. Those planes were similar in size to the Boeing 717, but they are getting close to retirement age. Planes in that size are often used for domestic flying on routes that aren't busy enough to fill a larger Boeing 737. Some of Southwest's 737s seat as many as 143 people.
Delta said the deal accelerates the revamping of its fleet, which has also included the elimination of turboprops. Because the 717s are replacing other planes, Delta said its overall flying level won't change.
The deal is part of a tentative agreement between the airline and its pilots. The agreement would also allow Delta to add 70 more 76-seat regional jets, for a total of 325, to be flown by feeder airlines. Pilots at big airlines like Delta fight to limit flying by so-called feeder carriers because they see those flights as threatening their jobs. Union leaders at Delta have approved the deal. Delta said the deadline for rank-and-file voting is the end of June.
For Southwest, the deal means it goes back to operating only Boeing 737s. Southwest has long favored running a single airplane type because it simplifies pilots training and aircraft maintenance. AirTran also flew mostly 737s, but it also liked the 717. AirTran bought the first one Boeing delivered, in 1999, and took one of the last ones in 2006.
When Southwest bought AirTran last year, it first said it would keep the 717s on some AirTran routes. But more recently it began looking for someone else to take the planes.
Southwest and AirTran have federal certification to operate as one airline, and Southwest has begun painting AirTran planes. But it has said it will be a long time before the AirTran name disappears.
Southwest has orders for more 737s, and it said its overall fleet count will stay about the same as the 717s leave. AirTran 717 pilots will train to fly the 737s. Flight attendants are already trained on both planes. Southwest said its plans to integrate AirTran workers into Southwest "over the next several years remain unchanged."
Shares of Atlanta-based Delta Air Lines Inc. fell 6 cents to $10.52 in afternoon trading. Dallas-based Southwest Airlines Co. fell 11 cents to $8.23.