Ryanair, the European low-cost airline, is adding five more Boeing 737-800s to its already considerable fleet of the single-aisle aircraft.
The airline already operates 300 of the mid-sized version of the Next Generation 737 and has unfilled orders for 180 more of the planes.
Ryanair is the world's largest operator of 737-800s. It received its first 737-800 in 1999. Last year Ryanair ordered 175 of the twin-engine planes.
The airline bolstered its fleet considerably at bargain prices after the 9-11 terrorist attacks taking advantage of other airlines' cancelling orders in the aftermath of the aircraft attack on the World Trade Center and the Pentagon.
From time to time Michael O'Leary, Ryanair's chief executives, makes noises about shifting from Boeing to Airbus or to Chinese manufacturers for its new planes, but thus far has always returned to Boeing.
Boeing has sold more than 11,000 737s. Some 3,700 of those have yet to be delivered. All 737s are built at Boeing's Renton plant where Boeing recently increased the production rate to 42 planes a month. The company plans to increase that rate to 47 monthly by 2017.