Are passengers told when an air marshal is on board?

No. The effectiveness of an In-Flight Security Officer depends on remaining unidentified, so their presence is kept confidential and is not disclosed to passengers.

Is there an air marshal on every flight?

No. IFSOs are deployed selectively by states based on threat assessments for particular routes or flights, not on every flight, because the resource is finite and is allocated where the assessed risk is highest.

Operations

In-Flight Security Officer (IFSO)

Also known as: In-Flight Security Officer · Air marshal · Sky marshal

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.

Reviewed by AeroVigil Analysis Desk · 2026-05-31

IFSOs provide an in-flight layer of security that complements ground measures such as screening and access control. Operating discreetly among the passengers, their role is to deter, and if necessary intervene against, attempts to seize or attack an aircraft in flight. Because their effectiveness depends on remaining unidentified, deployments are confidential and decided according to threat assessments for particular routes or flights rather than applied universally.

The deployment of IFSOs raises distinct operational and legal considerations: the carriage of weapons on board, coordination with the flight crew, the rules governing use of force, and bilateral agreements where officers operate on flights between states. These are addressed through international standards and national programmes, and the practice expanded notably after the September 2001 attacks as part of a layered security response.

Whether to request or accept IFSO coverage is a risk-based decision informed by the threat to specific routes. Aviation security intelligence that characterises route and destination threat — the kind AeroVigil aggregates — is part of the context in which such layered security decisions are weighed.

Frequently asked

Are passengers told when an air marshal is on board?: No. The effectiveness of an In-Flight Security Officer depends on remaining unidentified, so their presence is kept confidential and is not disclosed to passengers.
Is there an air marshal on every flight?: No. IFSOs are deployed selectively by states based on threat assessments for particular routes or flights, not on every flight, because the resource is finite and is allocated where the assessed risk is highest.

Related terms

Sources

ICAO Annex 17 — Security
ICAO Doc 8973 — Aviation Security Manual (restricted)