Boeing employees are pictured in front of a 737 MAX 8 produced for Southwest Airlines as Boeing celebrates the 10,000th 737 to come off the production line in Renton, Washington, U.S., March 13, 2018. REUTERS/Jason Redmond

FARNBOROUGH, England (Reuters) - U.S. airplane leasing firm Air Lease Corp announced on Tuesday a commitment to order as many as 78 Boeing Co BA.N single-aisle and wide-body airplanes in a deal valued at $9.6 billion at list prices.

Air Lease told a press briefing at the Farnborough Airshow that three 787-9s and the first 20 737 MAX airplanes in the total deal were firm purchases, while the remaining 55 737 MAX airplanes were provisional commitments.

Air Lease said it had flexibility for taking 737 MAX 8 and 9 variants and expected to take delivery between 2020 and 2024, though most of the jetliners would likely be delivered during the latter portion of that time frame.

Separately, Air Lease Chief Executive John Plueger said he was convinced, based on conversations with numerous airlines, there was strong interest and a need for a new mid-market jet Boeing is considering.

“There’s definitely strong interest in the entire global airline marketplace in this aircraft,” Plueger said. “The business case is up to Boeing, to be able to get there.”

Steve Udvar-Házy, executive chairman of Air Lease’s board, said later that choosing an engine for the mid-market jet would be one of the toughest choices Boeing has to make, adding it would be “nice” to have a choice between two engines.