Besides the door lock mechanism, how would you force a lock out?
Could the pilot have locked the door per procedure then had a big medical issue, heart attack etc?
Could the pilot have locked the door per procedure then had a big medical issue, heart attack etc?
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What I am gathering from the comments is that the cockpit has at least a couple of lock systems. The standard system would permit the pilot on the outside to gain entry on his own accord. The secondary system would require affirmative action by the pilot in the cockpit to effectively deadbolt the door so no one could get in. Obviously, this would require a deliberate act to lockout the pilot who left the cockpit. This would not have occurred if the pilot suddenly became incapacitated. Why would he deadbolt the door to exclude the pilot from gaining re-entry unless he was up to no good?
Can’t say, but there is a fail safe to prevent lockout. The remaining pilot has to force a lock at that point.