Two leading international aviation bodies have called for urgent global alignment in the management of disruptive passengers, as new data confirm a continued increase in unruly behaviour onboard commercial aircraft.
In a joint position paper recently released, the International Federation of Air Line Pilots’ Associations (IFALPA) and the International Federation of Air Traffic Controllers’ Associations (IFATCA) urged States to harmonise implementation of the International Civil Aviation Organization’s “4 Levels of Threat” framework for managing unruly passenger events.
The paper, Harmonised Implementation of the ICAO 4 Levels of Threat System for Managing Unruly Passenger Events (26POS02, 23 February 2026), warns that inconsistent adoption of the system is creating operational and safety challenges, particularly during cross-border operations.
A Persistent and Growing Safety Concern
Airlines and regulators remain concerned about the frequency and severity of disruptive passenger incidents. These range from failure to comply with crew instructions and verbal abuse to physical assault and attempts to breach the flight crew compartment.
According to the International Air Transport Association (IATA), which analysed more than 24,500 incident reports from over 50 operators worldwide, the rate of reported unruly passenger incidents increased in 2023 to one per 480 flights, compared with one per 568 flights in 2022. Non-compliance with crew instructions remained the most frequently cited behaviour, but reports involving verbal and physical abuse also rose.
The trend aligns with data from regulators, including the Federal Aviation Administration, the European Union Aviation Safety Agency and the UK Civil Aviation Authority.
Although such incidents involve only a minority of passengers, their impact is disproportionate. Disruptive behaviour can threaten the health, safety and security of passengers and crew, lead to costly diversions, and place additional strain on coordination between flight crews, air navigation service providers and law enforcement authorities.
ICAO’s “4 Levels of Threat” Framework
The classification system developed by the International Civil Aviation Organization (ICAO), detailed in ICAO Doc 8973 (Security Manual), provides a structured method for assessing the severity of unruly passenger behaviour:
- Level 1 – Disruptive behaviour, including suspicious or verbally threatening conduct
- Level 2 – Physically abusive behaviour
- Level 3 – Life-threatening behaviour
- Level 4 – Attempted or actual breach of the flight crew compartment
The framework is designed to create a common operational language between pilots, air traffic controllers, airlines, air navigation service providers and security agencies.
However, IFALPA and IFATCA note that only a limited number of States have incorporated the four-level system into their National Security Programmes. The absence of harmonisation can result in misunderstandings between pilots and air traffic controllers as to the severity of an onboard incident — particularly when aircraft are operating across multiple jurisdictions.
In time-critical situations, ambiguity over threat classification may affect decisions on priority handling, diversion planning and the level of response required on arrival.
Operational, Legal and Training Implications
The federations argue that harmonised implementation would deliver three principal benefits. These include improved operational safety, ensuring all stakeholders work within a common framework. Secondly, enhanced incident management, reducing communications workload and improving cross-border coordination. Lastly, training consistency, allowing standardised instruction for flight crews, controllers and ground responders.
Beyond operational procedures, industry bodies also highlight continuing legal gaps.
Under the 1963 Tokyo Convention, jurisdiction over offences committed onboard typically rests with the State of aircraft registration. In practice, this has created enforcement challenges at overseas airports, where local authorities may lack jurisdiction over incidents occurring on foreign-registered aircraft.
IATA member airlines report that such jurisdictional issues contribute to prosecutions not proceeding in approximately 60 per cent of unruly passenger cases.
To address these shortcomings, ICAO is encouraging States to ratify the 2014 Montreal Protocol 2014, which expands jurisdiction to the State of landing and strengthens the legal framework for prosecution. Adoption remains uneven.
Some countries, including Singapore, Australia, France, Finland and New Zealand, have introduced civil penalty regimes allowing authorities to issue administrative fines upon landing. While not suitable for the most serious offences, such systems can reinforce deterrence for lower-level misconduct without requiring full criminal proceedings.
Prevention and Public Awareness
Prevention remains a central pillar of the industry’s response. Annex 9 to the Chicago Convention requires governments to undertake awareness campaigns on prohibited conduct in aviation environments.
In 2021, the FAA launched a public awareness campaign supported by strengthened enforcement measures; reported incidents subsequently fell by around 60 per cent from peak levels.
IATA continues to provide airlines with guidance on de-escalation techniques, responsible alcohol service and restraint procedures, while supporting multi-stakeholder public campaigns across several jurisdictions.
A System Built on Standardisation
Aviation’s global safety architecture depends upon standardised procedures, shared phraseology and harmonised regulatory frameworks. IFALPA and IFATCA argue that the management of unruly passenger events should be no exception.
As passenger numbers continue to grow, the federations warn that inconsistent application of ICAO’s four-level threat system risks undermining clarity at precisely the moment it is most needed.
Their message is clear: in a global system, threat management must also be global.
