Of 235 retiring pilots who filed retirement papers with the Atlanta-based airline by Tuesday's deadline, 202 were early retirements, pilots union spokeswoman Karen Miller said.

Fifteen of the retiring pilots are based out of Salt Lake City, Delta's third largest hub, Miller said. Of that 15, 14 were pilots who chose early retirement. Pilots account for about 650 of Delta's 4,500 employees in Salt Lake City.

The tidal wave of retirements follows the pilots union's ratification of deep pay cuts Delta demanded. Pilots also agreed to reductions in vacation pay, changes to their pension plan and health benefits.

"Those pilots who did not choose to retire will be working under markedly different employment terms," Miller said.

Without the pilot concessions, which total $1 billion annually, Delta warned that it would have to seek bankruptcy protection to escape nearly $21 million in debt. Chapter 11 remains a possibility for the nation's third-largest airline.

Before the cuts, Delta pilot pay started at $50,000 and topped out - for about 50 veteran pilots nationally - at about $288,000.

The retirement wave is driven by the cuts in pilots' retirement benefits. Pilots who retired effective Wednesday will get retirement benefits based on their salaries before the pay cuts. Delta pilots who retire can receive half their pension in a lump sum and the other half as an annuity later.

The normal pilot retirement age at Delta is 60. Senior pilots with enough years of service can retire early at age 50.

Since the beginning of the year, nearly 700 pilots have resigned. More than 500 were early retirements.

Delta Chief Executive Jerry Grinstein has warned that the departure of hundreds of the airline's most experienced pilots could undercut its ability to keep planes in the air, particularly on lucrative overseas routes.

To keep its large aircraft flying, Delta reached an agreement with the pilots union in September that allows the company to rehire retired pilots, without hurting the pilot's retirement benefits.