The union representing pilots at Northwest Airlines Corp. approved a deal that seeks to prevent late-month spikes in the airline's flight cancellations such as those seen in June and July.

Saturday's vote by Northwest Airline Pilots Association confirms the tentative accord reached on August 1, said Northwest and its pilot union.

The agreement makes contractual changes on several work rules pertaining to international flying and settles an outstanding grievance. In exchange, Northwest will reinstate premium pay of 50 percent for all pilots flying more than 80 hours a month.

The airline said the pact was economically neutral with the premium-pay costs offset by the work rule changes and the grievance settlement.

The No. 5 U.S. airline suffered the extraordinarily high cancellation rates at the end of the last two months, blaming the problem on pilot absenteeism.

The Air Line Pilots Association, however, said absenteeism is not the problem. Rather, it said, the cancellations resulted from the airline having too few pilots to work the hectic summer flying schedule.

Work rules the pilots agreed to during the carrier's 20-month bankruptcy, which ended in May, often required pilots to spend more time in the air.