The plane's cockpit voice recorder (CVR) was reviewed, and no sounds consistent with the spoiler arming or automatically deploying were recorded by the CVR. The NTSB conducted two test flights of American Airlines MD-80 aircraft, which confirmed that manually arming the spoiler created an audible click noise, distinguishable from that made by automatic deployment of the system, that could be clearly heard on CVR playback. The NTSB also conducted ground tests on similar aircraft, including another American Airlines MD-80 for which the autospoiler system failed to deploy during a runway overrun, an event in Palm Springs, California that did not result in destruction of the aircraft.