Pilots conduct a pre-flight check in the cockpit of a jet before taking off from Dallas Fort Worth airport in Grapevine, Texas, on Dec. 2, 2020. Aviation experts say the incident on Sunday in which an off-duty pilot, riding in a jump seat in a cockpit, tried to disable a jetliner in midflight renews questions about the threat posed by airline workers who have special access to places where passengers can't go. (AP Photo/LM Otero, File)
