Two merging airlines still have one dispute to settle: Who should pay for damage from one airline’s aircraft to another?

Despite their planned merger in the near future, Hawaiian Airlines and Alaska Airlines have yet to settle the case of one airline’s aircraft damaging the other’s — and who is to blame for the mishap.

Industry blog Paddle Your Own Kanoo reports Hawaiian Airlines is suing the Federal Aviation Administration over damage one of their aircraft caused to a now retired Alaska Airlines aircraft.

Hawaiian Alleges FAA Ground Controller Caused Incident After Approving Engine Run-Up

The incident took place on July 21, 2021, at Oakland Airport (OAK) in California. According to Hawaiian’s account of the incident, airline maintenance engineers wanted to do an engine run-up on one of their aircraft, but the airport’s enclosure was unavailable.

Instead, they claim the ground controller at the time directed the aircraft to a remote taxiway so that it wouldn’t cause any problems for other aircraft. When an aircraft tug came to move the airframe into place, the airline claims the FAA ground controller then changed their mind and told the maintenance crew to perform the engine run-up at their location. When they did, the jet engine blast threw debris and aircraft stairs into a nearby Alaska Airlines Airbus A320.

Alaska demanded that Hawaiian pay for the damages, totaling over $6.2 million. However, Hawaiian says the FAA should be held liable for that amount, because they blame the ground carrier for the errant instructions. The FAA has not responded to the allegations, and a judge has not ruled in the case.

The airframe in question was ultimately taken out of the Alaska fleet as they moved back to an all-Boeing fleet after their merger with Virgin America. It was ultimately sold to Allegiant Air last year.

In December 2023, the two airlines announced plans to merge in a $1.9 billion purchase deal. If the lawsuit were to fail, it could turn into a case of the airline paying itself back for its own damages – but a ruling is still pending.