If US Airways Group CEO Doug Parker wants his plan to buy Delta Air Lines Inc. to succeed, he’s going to have to convince the likes of Boeing Co., the Coca-Cola Co. and IBM that it’s a good idea.

Parker on Wednesday made public a letter he sent to Delta CEO Gerald Grinstein, in which he offered to buy the Atlanta airline for $8 billion after Delta exits bankruptcy protection. It’s Parker’s second offer for Delta; the first time, Grinstein wasn’t interested.