Which security measure is applied to flight deck doors?

Reinforced doors that are secure and locked during flight represent a crucial security measure implemented to protect the flight deck from unauthorized access. These reinforced doors are designed to withstand significant physical attacks, thereby creating a barrier between the flight crew and any potential threats. Furthermore, during flight, these doors are typically kept locked to ensure that only authorized personnel, namely the flight crew, can access the cockpit. This measure is part of a comprehensive security approach aimed at preventing hijacking and ensuring the safety of the aircraft and its passengers.

Other options indicate less effective or secure practices. For instance, open access for crew members could lead to vulnerabilities, while electronic locks that can be disabled do not provide the constant level of security needed during flight. Lastly, relying solely on crew member presence for monitoring could be insufficient in a high-stress situation where prompt response is critical. The use of reinforced and locked flight deck doors is a proven strategy designed to safeguard the aircraft from potential threats.