Why is it important to ensure that exit doors are secure before takeoff?

Ensuring that exit doors are secure before takeoff is primarily important to prevent accidental opening during flight, which could compromise safety. If an exit door were to open during flight, it could create a sudden cabin depressurization, endangering the lives of everyone on board. This could lead to serious injuries or even fatalities due to the rapid change in pressure, as well as pose a risk of ejection of passengers or debris from the aircraft.

The security of exit doors serves as a critical safety measure, enabling the aircraft to maintain a controlled environment for passengers and crew. While there are other factors that contribute to the overall operation of an aircraft—like regulatory requirements or enhancing passenger comfort—none are as fundamental to the immediate safety of the flight as ensuring that all exit doors are securely closed and locked prior to takeoff.