Which document must all airport employees display to access secure areas?

To access secure areas of an airport, all airport employees must display an airport badge or ID badge. This requirement is critical for maintaining a controlled and secure environment, as the badge serves as a means of identification and approval, indicating that the individual has gone through the necessary background checks and security training. The airport badge signifies that personnel are authorized to be in restricted areas where sensitive operations occur, thereby helping to prevent unauthorized access and potential security breaches.

The other options, while they have their significance in the workplace, do not serve this specific purpose. For example, a flight operations manual would relate to operational procedures but does not function as a form of identification. A security training certificate demonstrates training completion but also lacks the identification aspect necessary for access control. An employee satisfaction survey is unrelated to security access and is typically used for assessing employee morale and workplace conditions rather than fulfilling security protocols. Therefore, the airport badge is essential for ensuring that only authorized personnel can enter secure areas, thereby enhancing the overall security of the airport environment.