Flight testing is a branch of aeronautical engineering that develops specialist equipment required for testing aircraft behaviour and systems. Instrumentation systems are developed using proprietary transducers and data acquisition systems. Data is sampled during the flight of an aircraft, or atmospheric testing of launch vehicles and reusable spacecraft. This data is validated for accuracy and analyzed before being passed to specialist engineering groups for further analysis to validate the design of the vehicle. The flight test phase accomplishes two major tasks: 1) finding and fixing any design problems and then 2) verifying and documenting the vehicle capabilities for government certification or customer acceptance. The flight test phase can range from the test of a single new system for an existing vehicle to the complete development and certification of a new aircraft, launch vehicle, or reusable spacecraft. Therefore, the duration of a particular flight test program can vary from a few weeks to many years. Aircraft flight test Civil aircraft There are typically two categories of flight test programs – commercial and military. Commercial flight testing is conducted to certify that the aircraft meets all applicable safety and performance requirements of the government certifying agency. In the United States, this is the Federal Aviation Administration (FAA); in Canada, Transport Canada (TC); in the United Kingdom (UK), the Civil Aviation Authority; and in the European Union, the European Aviation Safety Agency (EASA). Since commercial aircraft development is normally funded by the aircraft manufacturer and/or private investors, the certifying agency does not have a stake in the commercial success of the aircraft. These civil agencies are concerned with the aircraft's safety and that the pilot's flight manual accurately reports the aircraft's performance. The market will determine the aircraft's suitability to operators. Normally, the civil certification agency does not get involved in flight testing until the manufacturer has found and fixed any development issues and is ready to seek certification. Military aircraft Military programs differ from commercial in that the government contracts with the aircraft manufacturer to design and build an aircraft to meet specific mission capabilities. These performance requirements are documented to the manufacturer in the aircraft specification and the details of the flight test program (among many other program requirements) are spelled out in the statement of work. In this case, the government is the customer and has a direct stake in the aircraft's ability to perform the mission. Since the government