A special bankruptcy-proof pension program that Delta Air Lines established to retain its top executives during the airline industry's worst financial crisis hasn't kept some from leaving the company -- and taking their pensions with them.

Already, three of the 35 employees in the retention plan have left, taking along the initial chunk of their special pensions. And under the trust rules, nothing keeps the remaining executives in the plan from leaving the company, with full rights to their trusts, when they are fully funded early next year. In all, the trusts are expected to cost Delta, which is currently seeking concessions from its pilots, about $65 million by early next year.

While top executives -- including Chairman and Chief Executive Leo Mullin -- have received the bulk of the trust payments, company documents show that a number of less- senior employees also have received substantial payments under the plan, including the head of Delta's credit union and several company attorneys. Delta's employee pension obligations are underfunded by about $4.9 billion.