Two mechanics entered the cockpit of an airplane while it was at the gate, in violation of safety protocols. One mechanic pretended to be the pilot and jokingly manipulated some controls. Unaware, the engines had been left on. When the mechanic moved the throttles, the plane began moving down the runway. The mechanics fled screaming as the pilot was able to stop the plane before a collision. The incident made it clear why unauthorized personnel should not be in the cockpit.