Boeing (BA) has received a firm order from BOC Aviation for 50 737-8 Max jets as the Singapore-based aircraft leasing company prepares for rising demand for the single-aisle airplane.

The order expands BOC Aviation's 737 Max portfolio to 215 737-8s and 737-9s, Boeing said in a statement released late Sunday. The aircraft are scheduled for delivery through 2031 and include conversion rights to other 737 variants, BOC Aviation separately said Monday.

"With this transaction, we have commitments to purchase over 140 of these aircraft, which is the largest Boeing orderbook position in our history," BOC Aviation Chief Executive Steven Townend said.

The latest deal helps meet "increasing narrowbody demand as global air travel continues to soar," Boeing said.

"With single-aisle jets projected to account for 75% of global deliveries over the next 20 years, lessors are looking to build their order books to support airlines' fleet growth plans and replace less-efficient older jets," according to the plane manufacturer.

Traffic growth moderated in February, but still hit a record high, the International Air Transport Association said Monday. "The number of scheduled flights is set to continue increasing in March and April," Director General Willie Walsh said.

Boeing has secured total orders for 49 aircraft in the first two months of the year and delivered a combined 89 planes, data on its website showed. Boeing has exceeded delivery expectations through January and February, a trend that is expected to continue into the second quarter, RBC Capital Markets recently said.

RBC expects Boeing's 2025 free cash flow to improve by about $500 million to a negative $4.27 billion balance, taking into account robust deliveries of the company's Max jets and 787 Dreamliners. RBC is looking at a positive FCF next year.