TUI Travel PLC, a tour operator, has committed to buy 60 of Boeing Commercial Airplane’s 737 MAX passenger jets, an order valued at $6.09 billion at the listed prices. The order includes options for an additional 90 jets, according to reports.

TUI operates tour groups in about 180 countries, and reports over 30 million customers in more than 30 markets where it operates. Currently, TUI’s European operations have 141 aircraft in service.

“A major part of TUI Travel’s strategy is to provide our customers with unique holiday experiences that they can only get from us,” stated CEO Peter Long. "This multi-billion pound investment in the Boeing 737 MAX – representing the future generation of more fuel-efficient aircraft for our short and medium-haul programs - will be a further driver in delivering this.”

The 737 MAX is Boeing’s new series of narrow-body jets, being developed to replace the current model, the 737 Next Generation. It will be the fourth generation of the 737 since the airliner was introduced almost 50 years ago. Three variants of the new series — 737 MAX 7, MAX 8, and MAX 9 — are due for a commercial debut in 2017.

The jet builder has reported nearly 1,300 orders for the 737 MAX since introducing the new version in 2011.

Boeing said the 737 MAX builds on the strengths of Next-Generation 737, the best-selling commercial airliner. TUI’s jets will be powered by the CFM International LEAP-1B engines, and Boeing promises that airlines operating the 737 MAX will see a 13% improvement in fuel consumption.

According to Todd Nelp, vice president of European Sales, Boeing Commercial Airplanes, "TUI Travel’s airlines currently operate more than 135 Boeing airplanes and the commitment for 60 737 MAXs marks the next chapter in their continued fleet expansion, ensuring unrivalled efficiencies and superior passenger comfort. All of us at Boeing could not be more proud to see our relationship extended for years to come."