About 250 pilots that fly for an Air Transport Services Group Inc. (ATSG) unit which operates aircraft for DHL Express and Amazon.com Inc. walked off their jobs today, leading the unit, which employs the pilots, to cancel 75 of its flights at the start of the peak holiday shipping period.

The pilots' action prompted the unit, ABX Air Inc., to seek a court order restoring what is known in airline labor law parlance as the "status quo." This would require the pilots to return to their jobs while management and Local 1224 of the Teamsters union's Airline Professionals Association attempt to work out the main sticking point, which is determining how much ABX pilots should be paid for extra flying, especially entering peak season.

The pilots have argued that they have not been properly compensated for continuously flying "emergency" assignments during their off-duty time. The union said that ABX brought the current problem on itself by deliberately understaffing its pilot rolls for the past two years.

Wilmington, Ohio-based ABX said the pilots' decision to refuse work assignments violates the Railway Labor Act, the 1926 law that governs labor relations in the airline and railroad industries. The company also argued that the issues involved constitute a "minor dispute," which is to be resolved by arbitration under terms of their collective bargaining agreement.

Earlier this month, Judge Timothy S. Black of the U.S. District Court for the Southern District of Ohio ruled that the dispute was considered "minor" under the Act and should be addressed through the grievance and arbitration process in the agreement.

In a statement today, ABX Air President John Starkovich said the airline had notified its customers about "temporary interruptions" in ABX's flight operations, a step that will allow them to "adjust their networks" until the pilots return to work. ABX operates 45 flights a day for DHL Express. Along with ATSG's other airline unit, Air Transport International LLC, ABX operates 35 daily flights for Amazon.

Earlier this year, Amazon agreed to lease 20 Boeing 767 freighters from ATSG to support two-day deliveries of products ordered through its popular "Prime" service.

According to the pilots, ABX is to blame for the pilot shortfall because it refused to recall crews that were furloughed after DHL Express ceased domestic U.S. operations in January 2009. The company chose to hire new pilots, who would be paid at the bottom of the wage scale, rather than pay more to recall experienced DHL pilots, the union argued. ABX compounded the problem by waiting too long to hire pilots, and then hiring too few of them, according to the union.

Pilots at cargo carriers Atlas Air Worldwide Holdings Inc. and Polar Air Cargo Worldwide Inc., both based in Purchase, N.Y.; Florence, Ky.-based Southern Air Inc.; and Ypsilanti, Mich.-based Kalitta Air LLC will not cross the ABX pilot picket line should the company call on them to cover the flights, the union said. Polar and Southern are subsidiaries of Atlas.