Final answer:
Enhanced security screening procedures are implemented to protect large gatherings of people for special events and the facilities in which they gather.
Step-by-step explanation:
The aviation security measure implemented to protect large gatherings of people for special events and the facilities in which they gather is enhanced security screening procedures. To ensure the safety of attendees, airports may implement additional screening measures such as increased baggage checks, body scanning, and metal detectors. These measures are aimed at identifying and preventing potential threats, ensuring the safety of the event and its participants.