Ira Jackson, Atlanta aviation commissioner, resigned this week in the wake of reports concerning his alleged business relationship with a vendor at Atlanta's Hartsfield International Airport.

Mr. Jackson hand-delivered his resignation letter Sunday morning to the home of Mayor Maynard Jackson, forestalling the mayor's plan to suspend the commissioner while the city investigates the allegations.In a Sunday interview with the Atlanta Constitution, the mayor said he anticipated that the suspension would have led to the commissioner's discharge this week.

Filling in as acting aviation commissioner while the city gears up for a national search is Max Walker, deputy aviation commissioner.

Mayor Jackson told the Constitution the alleged business relationship dates back to 1985, but he would not divulge the name of the vendor.

The mayor, who persuaded the commissioner to resign his city commission seat of 20 years to take over the aviation commission in October 1990, said he feels betrayed that his longtime friend led him to believe there were no possible conflict of interest skeletons in his closet.

While a city commissioner, the former aviation commissioner was a paid consultant to Dobbs-Paschal Midfield Corp., the principal concessionaire at the Atlanta airport.

Dobbs-Paschal - battered in general by the recession and specifically by the demise of Eastern Airlines, which left an entire airport concourse vacant - is seeking a restructuring of its contract with the city.

Under the company's plan, the city would forgive $47 million of the $108 million Dobbs-Paschal owes the city.

Commissioner Jackson had weakened his standing in City Hall by publicly supporting the restructured contract the mayor has publicly disavowed.