Ryanair has taken delivery of its last Boeing 737NG, the 531th example since the airline's first order for the type in March 1998 and service entry of its first 737-800 one year later.

The Irish low-cost carrier has added on average 25 new 737-800s per year since 1999. The 737-800 remains the only type in Ryanair's fleet—all equipped with 189 seats—apart from one -700 in a VIP configuration used for occasional charter flights and pilot training. The Dublin-based LCC ranks as the largest 737-800 customer in the world and the largest Boeing operator in Europe.

“It’s the end of an era and the start of a new one,” Boeing said in a tweet. “Thanks for being all-#Boeing and get ready for the #737MAX “Gamechanger.”

Ryanair stands as the launch customer for the 737 Max 200, having placed orders for 135 and options on another 75. The variant can accommodate up to 200 seats, though Ryanair will fit its 737 Max 200s with 197 seats, an increase of 4 percent compared with its 737-800s. Deliveries should start in April and support Ryanair’s planned growth to 200 million passengers annually by 2024.

While remaining true to its low-cost business model, Ryanair has decided to reverse its historic approach to the IATA Operational Safety Audit (IOSA) program. Like most LCCs, Ryanair has never felt the need to become IOSA certified.

IATA director general and CEO Alexandre de Juniac announced Ryanair’ s change of mind at the association’s global media day in Geneva. An executive with the airline who requested anonymity confirmed to AIN it would undertake the IOSA certification process, adding that as the biggest airline in Europe in terms of passenger numbers it welcomes an independent view of its safety processes. The executive also said IOSA certification would prove useful for certain contractual engagements, while cautioning that becoming IOSA certified would not mean Ryanair would become an IATA member at the moment. “We do not interline, and we typically do avoid that kind of expense,” he said.