Marriott Considering Selling Unit: Marriott Corp. is discussing the sale of its airline catering division to a management-led group, a deal that analysts said could bring the hotel conglomerate as much as $600 million. Under the proposal, which Marriott described as a transfer, the Washington-based hotel and restaurant concern would retain a continuing financial interest in the unit, called Marriott In-Flite Services. A Marriott spokesman declined to say how far the talks with the investor group have gone. The division has 19,000 employees providing food service to more than 150 airlines around the world. Revenue in 1988 was $800 million.