Boeing 737 MAX airplanes are seen parked at a Boeing facility on August 13, 2019 in Renton, Washington.

David Ryder | Getty Images

Southwest Airlines is upsizing its order for Boeing’s smallest 737 Max model by nearly three-dozen planes, the carrier said Tuesday, citing improving travel demand.

The Dallas-based airline said in a filing that it will increase its 22 firm orders by 34 Boeing 737 Max 7 aircraft, exercising options, bringing its total order book for that plane to 234. The all-Boeing 737 airline also has firm orders for 149 Max 8 planes, as the company retires older 737s.

Southwest expects its 2022 capital expenditures to total $1.5 billion, up from a previous estimate of $700 million.