 The C-17 Globemasters are based at Pápa Air Base in Hungary.A unique feature of the SAC program is its aviation safety certification system.This system called the Concept of Total Aviation Safety (CONTAS) is based upon a heavily adapted version of the United States Air Force C-17 safety system, the principles of design and operation of heavy airlift aircraft as described by the European Aviation Safety Agency (EASA), and the mandatory requirements of the Hungarian National Transport Authority who are the national authority that registers the aircraft and certifies the operations of the HAW, and the support provided by NAM PO.