Delta Air Lines Inc. (DAL) chief executive Gerald Grinstein (search) told pilots Friday the financially troubled carrier needs $1 billion in concessions from them, insisting their proposal for up to $705 million in cuts is inadequate.

Grinstein said in an open letter to pilots that the money the airline is asking for is the minimum amount it needs to survive.

"While I respect the negotiating process and believe details are best resolved privately at the table,d it was making a good-faith effort to save the Atlanta-based airline from bankruptcy. It had said it hoped management would work with them on a solution.

Grinstein's letter did not mention how much of a pay cut he was seeking, only the total amount of savings the airline needs.

Delta's pilots are among the highest paid in the nation. They earn on average between $100,000 to $300,000 a year, according to the company.

Delta, the nation's third-largest airline, has lost more than $5 billion and laid off 16,000 employees in the last three years. It has been hit hard by high fuel costs and competition from low-fare carriers.