Technical Standards Order (TSO). To meet those requirements the design documents are examined for compliance with the applicable Minimum Operating Performance Standards (MOPS) applicable to that sub-assembly. MOPS are published by expert industry groups such as: RTCA Inc., EUROCAE, and SAE. When aircraft are produced to meet a given TC, each one need not be tested as rigorously but the confidence demonstrated by the TC is conferred, when the aircraft has been assigned a certificate of airworthiness (CoA). A CoA is issued for each aircraft that is properly registered if it conforms to its type design and ready for safe operation. The CoA is valid and the aircraft may be operated as long as it is maintained in accordance with the rules issued by the regulatory authority. History The concept of a 'type certificate' was introduced by the "Air Navigation Regulations" published in May 1919 by the UK's Secretary of State for Air, Winston Churchill. The Buhl-Verville CA-3 Airster was the first aircraft to receive a type certificate in the US, (i.e. A.T.C. No. 1) issued by the Aeronautics Branch of the Department of Commerce on March 29, 1927. Aircraft type certification Prototype Initially, the applicant design organisation submits documents to their local aviation regulating body, detailing how the proposed aircraft type design would fulfill the airworthiness requirements. After investigations by the regulator, the final approval of such documents (after the required comments and amendments in order to fulfill the laws), becomes the basis of the certification. The firm follows it and draws a proposed timetable of actions required for certification tests. With the application, the regulations to be applied will usually be frozen for this application for a given amount of time in order to avoid a situation where the applicant would have to change the design as a result of changed regulation. An initial design sample known as a prototype is built. This refers to either the aircraft, the engines or the propeller, depending on the basis of the certification. For the purpose of illustration, the discussion shall be limited to the aircraft. Normally a few prototypes are built, each subject to different tests. The prototypes are first used for ground and system tests. One of the prototypes (known as the "static airframe") is subject to destructive testing, i.e., the prototype is subject to stress beyond normal and abnormal operations until destruction. The test-results are compared with initial