Ryanair DAC is an Irish ultra low-cost carrier founded in 1984. It is headquartered in Swords, Dublin, Republic of Ireland and has its primary operational bases at Dublin and London Stansted airports. It forms the largest part of the Ryanair Holdings family of airlines and has Ryanair UK, Buzz, Lauda Europe, and Malta Air as sister airlines. In 2016, Ryanair was the largest European budget airline by scheduled passengers flown, and it carried more international passengers than any other airline.Ryanair Group operates more than 400 Boeing 737-800 aircraft, with a single 737-700 used as a charter aircraft, as a backup, and for pilot training. The airline has been characterized by its rapid expansion, a result of the deregulation of the aviation industry in Europe in 1997 and the success of its low-cost business model. Ryanair's route network serves 40 countries in Europe, North Africa (Morocco), and the Middle East (Israel, Jordan and Turkey).The company has often been criticised for its poor working conditions, heavy use of extra charges, bad customer service, and tendency to intentionally generate controversy in order to gain free publicity.