Airport security includes the techniques and methods used in an attempt to protect passengers, staff, aircraft, and airport property from malicious harm, crime, terrorism, and other threats.

Aircraft hijacking is the unlawful seizure of an aircraft by an individual or a group. Dating from the earliest of hijackings, most cases involve the pilot being forced to fly according to the hijacker's demands. There have also been incidents where the hijackers have overpowered the flight crew, made unauthorized entry into the cockpit and flown them into buildings – most notably in the September 11 attacks – and in several cases, planes have been hijacked by the official pilot or co-pilot; e.g., Ethiopian Airlines Flight 702.