test pilot 
noun
A pilot who flies an aircraft to test its performance.He is currently a test pilot with the Aircraft Research and Development Test Unit at RAAF Base Edinburgh in South Australia....
- The test pilot found the aircraft remarkably stable and easy to control, and a pleasant surprise to all of us.
- In this account of life as a test pilot, fighter pilot, and combat commander, Ross tells his Air Force story with wit, candor, and refreshing irreverence.