SunExpress is exercising options for 10 additional Boeing 737 MAX 8 planes in a bid to renew its fleet.
The purchase, valued at $1.2 billion according to list prices, adds to a previous SunExpress order for 32 MAX planes.
Jens Bischof, CEO of SunExpress, commented: "We have a long-standing, strong and trustful relationship with Boeing and thus we decided to turn our option into an order.
"We stand behind our strategic decision to phase the 737 MAX into our fleet for all of its economic and ecological advantages, mid- and long-term.
"We have full confidence that Boeing will deliver us a safe, reliable, and efficient aircraft. However, it goes without saying that this requires the undisputed airworthiness of the model, granted by all relevant authorities. Our utmost priority at SunExpress is and has always been safety."