Boeing and Ryanair today finalized a firm order for 175 Next-Generation 737-800 airplanes valued at $15.6 billion at list prices. The order, originally announced as a commitment in March, is Boeing’s largest ever aircraft order from a European airline.

At a signing ceremony today at the 2013 Paris Air Show, Michael O’Leary, president and CEO of Ryanair, joined Ray Conner, Boeing Commercial Airplanes president and CEO, to finalize the historic deal.

O’Leary flew into the air show on one of Ryanair’s 303 737-800s, which bore a special livery celebrating the agreement.

“Ryanair is proud to buy Boeing, who make great aircraft, and the 737-800 has been the foundation of Ryanair’s recent successful growth due to its great engineering and phenomenal reliability,” said O’Leary. “These 175 new airplanes will enable us to lower costs and airfares even further. They provide Ryanair with the additional capacity to exploit substantial growth opportunities that now exist as many of Europe’s flag and regional airlines are restructuring and are reducing their short-haul operations.”

“We are delighted to finalize this order. It is a testament to the value the Next-Generation 737 family brings to Ryanair,” said Conner.  “As the most efficient, reliable, large single-aisle airplane flying today, the Next-Generation 737 has been and will continue to be the cornerstone of the Ryanair fleet. I could not be more proud to see the partnership between Ryanair and The Boeing Company extended for the years to come.”

Boeing press release