ATLANTA — Delta Air Lines Inc. pilots voted overwhelmingly in favor of changes to their contract that will give them pay raises, an equity stake and other benefits, but also will give management more leeway as part of a proposed combination with Northwest Airlines Corp.

Voting, which started May 1, ended Wednesday. A letter from the chairman of the union's executive committee, Lee Moak, to fellow pilots said 78 percent of pilots who voted approved of the changes.

The contract covers more than 7,000 pilots at Atlanta-based Delta. Northwest's 5,000 pilots are not part of the agreement.

Out of 6,073 eligible Delta pilots, 4,590 cast their vote. Of those, 3,580 voted in favor of ratifying the agreement, Moak said.

Delta agreed to extend its existing collective bargaining agreement with its pilots through the end of 2012. The revised contract provides the Delta pilots a 3.5 percent equity stake in the new company.

In exchange, the company will be able to place the Delta code and brand on Northwest flights and retain Northwest's large stake in Midwest Airlines, while maintaining those two carriers' separate operational status. The scope clause of the Delta pilot contract could have prevented Delta from doing those things had it not been amended as part of the agreement that has now been ratified.

Moak said the contract agreement will become effective when the combination of Delta and Northwest closes, unless the agreement is first superseded by a joint collective bargaining agreement between Delta management and the pilots of Delta and Northwest.

Delta Chief Executive Richard Anderson and Northwest CEO Doug Steenland later Wednesday reiterated to concerned lawmakers in Washington that no hubs will be closed and no large-scale layoffs are planned. But neither would estimate how many corporate jobs would be cut when asked by House aviation subcommittee chairman Jerry Costello, D-Ill.

During congressional hearings last month, Anderson estimated that no more than 1,000 corporate positions would be eliminated. The executives said Wednesday they would provide the subcommittee with a formal estimate within 60 days.

Delta announced April 14 that it had agreed to acquire Northwest in a stock-swap deal that would create the world's largest carrier. The deal, which calls for the combined carrier to be called Delta and to be based in Atlanta, must be approved by shareholders and regulators. Delta pilots have been granted a voting seat on the board of the combined company.

Union leaders from Delta and Northwest, based in Eagan, Minn., hope to work out an agreement on a merged contract and an integrated seniority list. They could not agree on the seniority issue before the combination was announced.

Northwest pilot union Chairman David Stevens, in testimony prepared for a hearing before lawmakers in Washington on Wednesday, said he is concerned the reason for the Delta pilots' revised contract "may be to put economic pressure on Northwest pilots to agree to an unfair seniority list."

"We will not do that. Contract terms can be changed, seniority is forever," Stevens said. Moak also was at the hearing to testify.

The two airlines believe the deal is necessary to allow them to be profitable in the future amid fuel prices that have soared to more than $125 a barrel.

Delta's pilot leaders have wavered on the issue of whether they would support arbitration to settle the seniority dispute with Northwest pilots.

Before the combination announcement, Moak said he opposed arbitration. Then, on April 21, he suggested that he was open to arbitration with Northwest pilots.

In his letter to fellow pilots Wednesday, Moak did not dismiss the idea of arbitration, but said it isn't the union's preference.

Moak said that while union merger policy can result in arbitration, Delta's pilot leaders "believe that turning over the fate of our seniority list to an arbitrator and the timeline to a policy manual is an abdication of leadership and that the best solution involves pilots negotiating with pilots to achieve a fair and equitable list."

He said the Delta pilots union's goal is for both the joint contract and the integrated seniority list to be completed before the closing of the combination of the two airlines.

Pilot union negotiators from Delta and Northwest were scheduled to meet for two days starting Wednesday in Washington to begin a renewed effort to achieve a joint contract, according to a memo from Northwest's pilots union to its members. The meeting was not expected to address seniority list integration, the memo said.

Seniority is important for pilots, because those at the top of the list get first choice on vacations, the best routes and the bigger planes that they get paid more for flying. It's also the reason pilots don't often leave to go work for another airline.