Dhaka, April 29 -- Bangladesh's flag carrier Biman Bangladesh Airlines is poised to sign a $3.7 billion agreement with US aerospace giant Boeing to purchase 14 aircraft, marking the largest fleet expansion in the airline's history.

The deal is expected to be formalised on Thursday evening at a ceremony in Dhaka, attended by senior government officials, diplomats and aviation executives, according to people familiar with the arrangements.

Under the agreement, Biman will acquire a mix of long-haul and short-haul aircraft, including eight Boeing 787-10 Dreamliner, two Boeing 787-9 Dreamliner and four Boeing 737-8 MAX jets. The list reflects a strategic shift towards expanding long-distance capacity while maintaining flexibility on regional...