"Delta finds it to be an interesting concept and could be a long-term replacement for some 757s and 767s," spokesman Morgan Durrant said. "Delta is actively engaged with Boeing on this and we will continue a healthy dialogue with them as the program matures."
Boeing prodded U.S. officials to scrutinize Delta's purchase of Bombardier jets after accusing the Canadian rival of selling planes below market price, thanks to subsidies it gets from the Canadian government.
"We've engaged with our customers and the feedback we've received is the desire for an airplane that's bigger than the 757 with more range," Boeing spokesman Tom Kim said.
The new Boeing planes would seat between 200 and 270 passengers and have a range of about 5,000 nautical miles.