Flight testing is a branch of aeronautical engineering that develops specialist equipment required for testing behaviour and systems of aircraft or testing the atmospheric phase of launch vehicles and reusable spacecraft. 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 to further modify the vehicle design during development, or to validate the design of the vehicle.
The flight test phase accomplishes two major tasks: 1) finding and fixing design problems and then 2) verifying and documenting the vehicle capabilities when the vehicle design is complete, or to provide a final specification 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 years.