Why must security checks be completed before a flight?

Security checks prior to a flight are crucial primarily to ensure that no prohibited articles are present onboard. This includes weapons, explosives, or any other items that could pose a threat to the safety of the aircraft and its passengers. By thoroughly screening passengers and their belongings, security measures are designed to prevent incidents that could jeopardize safety during the flight.

While confirming passenger identities and checking luggage weight are important aspects of air travel, they are not the primary focus of security checks aimed at addressing safety risks. On-time departures are also a concern for airlines and passengers but are not directly related to the security protocols that are established to secure the aircraft against potential threats. Therefore, the correct answer highlights the foremost objective of flight security—maintaining a safe travel environment by prohibiting dangerous items from boarding the aircraft.