Northwest Airlines pilots leaders unanimously approved a tentative Delta Air Lines-Northwest pilot labor agreement Friday, following a similar move by Delta's pilot leadership Wednesday.

With both leadership groups endorsing the tentative agreement, the next step is to put the deal up for a vote by rank-and-file pilots.

For Delta pilots, that process could take a month or longer, including giving details of the contract to pilots, followed by voting. The Northwest pilots union plans to begin telling pilots about the agreement at meetings in July.

The tentative agreement would take effect at the close of the proposed merger between Atlanta-based Delta and Eagan, Minn.-based Northwest.

It would bring Northwest pilots' pay to the level of Delta pilots. It also includes 4 percent to 5 percent annual pay raises from 2009 through 2012 and equity in the combined company for Delta and Northwest pilots.

The union leaders also agreed to a process to integrate seniority lists. If negotiations do not yield an agreement, details will be worked out through binding arbitration before the merger closes. The merger is expected to close by year-end, pending regulatory approval.