Glossary

An act of unlawful interference is a deliberate act, or attempted act, that endangers the safety of civil aviation. It is the umbrella legal term used by ICAO for hijacking, sabotage, attacks on aircraft or airport facilities, the seizure of aircraft, the introduction of weapons or dangerous devices, and the use of an aircraft itself as a weapon.

An Air Defense Identification Zone (ADIZ) is a publicly defined area of airspace, often extending beyond a state's sovereign airspace over international waters, within which aircraft must identify themselves, report their position and follow specific procedures in the interest of national security. An ADIZ is a security and identification requirement, not a claim of sovereignty.

ADS-B, or Automatic Dependent Surveillance–Broadcast, is a surveillance technology in which an aircraft determines its own position — usually from GNSS — and periodically broadcasts it, along with identity and other data, so that air traffic control and other aircraft can receive it. It supports surveillance without relying solely on ground radar and is the basis of much publicly available flight tracking.

Air cargo security is the set of measures that protect the air cargo and mail supply chain against the introduction of explosives or other prohibited items into aircraft. It relies on a chain of trusted, regulated parties — such as regulated agents and known consignors — together with screening, so that cargo can be shown to be secure from origin to aircraft.

Air Traffic Flow Management (ATFM) is the service that balances air traffic demand against the available capacity of airspace and airports, regulating the flow of flights to prevent overload. It uses measures such as departure slots and rerouting to keep traffic within safe and efficient limits when demand would otherwise exceed capacity.

Aviation security intelligence is the systematic collection, analysis and dissemination of threat information to support decisions about routes, destinations, airports and crew. It is anticipatory rather than reactive, aiming to identify risks such as conflict, terrorism, civil unrest and airspace threats before they affect operations, so that operators can act on a forward-looking picture.

AVSEC, short for aviation security, is the discipline of protecting civil aviation against acts of unlawful interference, such as hijacking, sabotage, attacks on aircraft and airport facilities, and the introduction of weapons or explosives. It combines screening, access control, intelligence and procedures, and is governed internationally by ICAO Annex 17.

A Conflict Zone Information Bulletin (CZIB) is a notice that warns aircraft operators about risks to civil aviation in specific airspace over or near a conflict zone. In Europe these bulletins are issued by EASA, and they consolidate state and intelligence assessments so operators can make informed routing and overflight decisions.

Conflict zone overflight risk is the danger that civil aircraft face when flying over or near an area of armed conflict, principally the threat of being damaged or shot down by surface-to-air missiles, man-portable air-defense systems or other anti-aircraft weapons.

Counter-UAS (C-UAS) refers to the systems and procedures used to detect, track, identify and, where lawful, defeat unmanned aircraft that pose a threat to an airport or other protected site. Because drones evade traditional perimeter defences, C-UAS extends airport protection into the surrounding airspace.

Crew layover security is the protection of flight crews during rest periods away from their home base, such as at hotels and in destination cities. Because crew are off the airfield and in the public domain during layovers, they can be exposed to local crime, civil unrest, terrorism and other landside risks that vary widely by destination.

A danger area is airspace of defined dimensions within which activities dangerous to the flight of aircraft may exist at specified times. Unlike a prohibited or restricted area, a danger area does not by itself forbid or condition entry — it warns pilots that hazardous activity, such as live firing or military exercises, may be taking place.

A diversion is a change of an aircraft's intended destination during a flight, while an alternate aerodrome is an airport to which a flight can proceed when landing at the planned destination becomes inadvisable or impossible. Operators are required to nominate suitable alternates during planning and to carry the fuel to reach them.

Duty of care is an operator's legal and moral obligation to take reasonable steps to protect the safety and wellbeing of its crew and passengers. In aviation it extends beyond the aircraft to the wider journey, including ground transport and crew rest at destinations, requiring foreseeable risks to be identified and reasonably mitigated.

EASA, the European Union Aviation Safety Agency, is the EU body responsible for civil aviation safety and certain security-related functions across its member states. It develops common rules, certifies aircraft and organisations, and issues advisories — including the Conflict Zone Information Bulletins that warn operators about risks over and near conflict areas.

The FAA, or Federal Aviation Administration, is the United States national civil aviation authority. It regulates and oversees all aspects of US civil aviation, including the certification of aircraft and personnel, operating rules, and the management of the national airspace system, and it issues the NOTAMs and Temporary Flight Restrictions that govern access to US airspace.

A Flight Information Region (FIR) is a defined volume of airspace within which a designated authority provides flight information service and alerting service. FIRs are the largest regular division of airspace and together cover the entire planet, including the oceans.

A Flight Risk Assessment Tool (FRAT) is a structured method that scores the cumulative risk of a specific flight before departure by combining individual risk factors into an overall picture. It is a practical expression of safety management system risk principles, helping crews and operators identify when a flight's combined exposure warrants additional review or mitigation.

GNSS, or Global Navigation Satellite System, is the collective term for the satellite constellations that provide positioning, navigation and timing to aircraft, including GPS (United States), Galileo (EU), GLONASS (Russia) and BeiDou (China). Modern flight operations depend on GNSS for navigation, approaches and the precise timing many avionics rely on.

GPS jamming is interference that overwhelms or blocks the weak signals from satellite navigation systems, causing receivers on an aircraft to lose their position fix. It denies positioning rather than falsifying it, and is a recognized and growing threat to flight operations near conflict and contested regions.

GPS spoofing is interference that transmits counterfeit satellite navigation signals to deceive an aircraft's receiver into computing a false position, velocity or time. Unlike jamming, which denies a fix, spoofing makes the receiver confidently report an incorrect location.

ICAO, the International Civil Aviation Organization, is the United Nations specialised agency that develops the international Standards and Recommended Practices (SARPs) governing civil aviation safety, security, efficiency and environmental protection. Established by the 1944 Chicago Convention, it provides the common framework that national authorities translate into binding law.

ICAO Annex 17 is the international standard for aviation security, titled "Security — Safeguarding International Civil Aviation Against Acts of Unlawful Interference." Adopted under the Chicago Convention, it sets out the Standards and Recommended Practices (SARPs) that contracting states are expected to implement to protect civil aviation worldwide.

An In-Flight Security Officer (IFSO), commonly known as an air marshal or sky marshal, is a trained, usually armed officer deployed covertly on board a flight to prevent and respond to acts of unlawful interference such as hijacking. IFSOs are deployed by states on a risk basis and their presence is not disclosed to passengers.

An insider threat in aviation is the risk posed by a person with legitimate, trusted access — such as an employee, contractor, crew member or service provider — who exploits that access to harm civil aviation, whether deliberately, through coercion, or by negligence. Because insiders bypass the perimeter controls designed to stop outsiders, they are recognised as one of the most serious security challenges.

Landside and airside describe the two principal security zones of an airport. Landside is the publicly accessible area before security screening, such as the forecourt, check-in halls and arrivals. Airside is the access-controlled secure area beyond screening, including departure gates, ramps and runways, which only screened and authorized people may enter.

A MANPADS is a man-portable air-defense system: a lightweight, shoulder-launched surface-to-air missile designed to be carried and fired by a single person or small team. Originally military weapons, MANPADS are a recognised threat to civil aviation because their proliferation in conflict zones puts aircraft at risk during the lower-altitude phases of flight.

A National Civil Aviation Security Programme (NCASP) is the central document through which a state codifies how it meets its aviation security obligations under ICAO Annex 17. It defines the legal basis, roles, responsibilities and security measures applicable to civil aviation within that state, and provides the framework for airport, airline and operator security programmes.

A NOTAM is a formal notice issued by aviation authorities that alerts pilots and operators to temporary hazards, changes or restrictions in the airspace, at an airport or in navigation services that are essential to flight safety.

Open-source intelligence (OSINT) is intelligence produced from publicly available information, such as news media, official government and aviation advisories, verified social media and publicly accessible flight data. In aviation security it is one input among several, valued for its breadth and timeliness but requiring verification before it informs operational decisions.

An Operations Control Centre (OCC) is the central facility from which an airline monitors and manages its live flight operations. Staffed around the clock, it coordinates flight dispatch, crew, aircraft, maintenance and ground resources, and serves as the operator's hub for reacting to disruptions, weather, security events and other fast-moving developments.

An overflight permit, or diplomatic clearance, is the authorisation a state grants for an aircraft to transit its sovereign airspace. It rests on the principle that every state has complete and exclusive sovereignty over the airspace above its territory, so transit is a permission to be obtained rather than an automatic right — particularly for non-scheduled, state or military flights.

A PIREP, or Pilot Report, is a report of actual flight conditions observed and transmitted by a pilot in flight. PIREPs provide real-time, first-hand information about phenomena such as turbulence, icing, cloud layers, visibility and other conditions that instruments and forecasts may not fully capture.

Prohibited airspace is a defined volume of airspace within which aircraft flight is not permitted at all, established by a state for reasons of national security or public safety. It is the most restrictive category of special-use airspace.

A restricted area is airspace of defined dimensions within which the flight of aircraft is restricted in accordance with specified conditions. Unlike a prohibited area, where flight is forbidden outright, a restricted area may be entered under stated conditions or with authorisation — often because hazardous or sensitive activity takes place there at certain times.

A Safety Management System (SMS) is a structured, organisation-wide approach to managing safety risk, encompassing the policy, accountabilities, hazard identification, risk assessment and assurance processes that an aviation organisation uses to manage safety proactively. It is mandated internationally under ICAO Annex 19 and is the foundation for tools such as the flight risk assessment tool.

A Security Management System (SeMS) is a structured, organisation-wide framework for managing aviation security risk, applying the proactive, risk-based methodology of a Safety Management System to the security domain. It establishes security accountabilities, threat and risk assessment, performance monitoring and a culture of security throughout an organisation.

A SIGMET (Significant Meteorological Information) is a weather advisory issued by a meteorological watch office warning of specific en-route weather phenomena hazardous to aircraft, such as thunderstorms, severe turbulence, severe icing, volcanic ash or tropical cyclones. SIGMETs cover a defined area and validity period and are disseminated to operators and crews.

Sovereign airspace is the airspace above a state's land territory and territorial waters, over which that state has complete and exclusive control. The freedoms of the air are the set of negotiated rights — beginning with the right to overfly and to make technical stops — that allow international air services to operate across those sovereign boundaries.

Special use airspace is airspace within which activities must be confined because of their nature, or where limitations are imposed on aircraft not part of those activities. It is the umbrella category that includes prohibited, restricted and danger areas, as well as other designations used to separate hazardous or sensitive operations from general air traffic.

A standoff attack against aviation is an assault launched from outside the airport perimeter, using weapons that strike at a distance — such as mortars, rockets, rocket-propelled grenades or small-arms fire — to hit aircraft, the apron, terminals or other facilities. Because the attacker never has to breach the fence, standoff attacks defeat the access-control and screening measures focused on the boundary.

A Temporary Flight Restriction (TFR) is a regulatory action that temporarily restricts aircraft operations within a defined area, usually for safety or security reasons such as wildfires, natural disasters, major public events or the movement of senior government officials.

An Upper Information Region (UIR) is a defined volume of high-altitude airspace within which a designated authority provides flight information and alerting services. It is the upper-level counterpart to a Flight Information Region (FIR), and a single UIR may overlie several FIRs that handle the lower airspace beneath it.

The UAS or drone threat is the risk that unmanned aircraft pose to civil aviation, ranging from unintentional incursions into airport airspace that disrupt operations, to deliberate use of drones for surveillance, smuggling, or as weapons. Even small drones can force runway closures and present a collision hazard to crewed aircraft.