American Airlines and its pilots union will begin arbitration hearings on March 9, if the two sides do not reach a labor contract before then, the union said in a message on its website.

The new contract would cover pilots at both American and US Airways, which merged last December. A key issue will be integrating seniority lists of the pilot groups.

When US Airways merged with America West in 2005, the two pilot groups never fully integrated because of legal disagreements related to seniority and have remained separate at US Airways, which is the dominant carrier at Philadelphia International Airport.

American management has said it wants to begin the arbitration sooner than March, "but thus far availability of the arbitrators has precluded an earlier start date," according to the Allied Pilots Association.

- Linda Loyd