Watch lists and Interpol checks at the airport

What gets checked at the border

Border checks look at two things: the document and the person. The document check asks whether the passport has been reported lost, stolen, revoked or invalid. The person check asks whether the traveller is wanted, missing or listed as a security risk ^2,3.

Checks can start before you fly. Airlines send passenger data to governments in advance, and UN Security Council resolution 2396 of December 2017 requires states to develop watch lists or databases of known and suspected terrorists for use by border, customs, police and intelligence agencies ¹¹. In the EU, the Court of Justice has said advance PNR checks may compare data only against non-discriminatory databases of persons or objects sought or under alert ¹⁵.

Interpol I-24/7 and the SLTD database

Interpol has 196 member countries. Each has a National Central Bureau (NCB), staffed by national police, that acts as the country's contact point ¹. I-24/7 is Interpol's secure communications system. It links all member countries and lets police reach each other and Interpol's databases in real time ¹.

Countries can extend database access from the NCB to frontline officers at airports, seaports and land crossings. Officers can cross-check results against national databases at fixed and mobile checkpoints ³. First-line databases cover stolen, lost, revoked or invalid travel documents, Notices, criminal histories linked to cooperation requests, travel documents linked to Notices, stolen vehicles and vessels, and illicit firearms ³.

The Stolen and Lost Travel Documents database, or SLTD, held around 138 million records according to Interpol. It was searched 3.6 billion times in 2023 and produced 232,423 positive matches that year ². Only the country that issued a document can add it, through its NCB or another authorised agency ².

Private companies can screen documents too. Interpol's I-Checkit service lets partners such as travel operators and banks submit identity document data over an encrypted link. It is checked against SLTD and documents linked to Red Notices. The link gives neither side access to the other's databases ⁶.

Interpol notices

Notices are international requests for cooperation or alerts. The General Secretariat issues them at the request of a member country's NCB. International criminal tribunals, the International Criminal Court and the UN can request them as well ⁴.

A Red Notice seeks the location and arrest of a person wanted for prosecution or to serve a sentence. A Yellow Notice helps find missing persons. A Blue Notice gathers information on a person's identity, location or activities. Green and Orange Notices warn of threats to public safety. Black Notices concern unidentified bodies. Purple Notices share criminal methods. A Silver Notice pilot traces criminal assets. UN Security Council Special Notices cover people and entities under UN sanctions ⁴. Countries can send diffusions directly to each other, using the same colour system ⁴.

Interpol states that a Red Notice is an international alert for a wanted person, but it is not an arrest warrant. Each country applies its own law to decide whether to arrest ⁵. Interpol says a task force of lawyers, police officers and specialists reviews every Red Notice request for compliance with its rules. Non-compliant notices are cancelled and countries are asked to remove them from national databases ⁵.

National and regional watch lists

National lists sit alongside Interpol data. In the US, the Threat Screening Center keeps the government's consolidated terrorism watchlist. It was formed after the 11 September 2001 attacks, when separate lists were merged. The FBI says it lists people reasonably suspected of involvement in terrorism or related activities ⁹. Only government agencies can nominate names. Race, ethnicity, religion, protected beliefs or hunches cannot be grounds for listing ⁹. The State Department, CBP, TSA and other agencies use it. The No Fly list is a very small subset ⁹. The centre does not confirm whether a person is listed ⁹.

For flights in the US, TSA's Secure Flight programme matches the full name, date of birth and gender travellers give at booking against government watch lists before a boarding pass is issued. DHS says airlines did this matching before Secure Flight ¹².

In Europe, the Schengen Information System is the largest shared database for security and border management. It began operating in 1995 and was renewed in March 2023 ¹⁴. eu-LISA reported over 17.7 billion searches in 2025, up 18 percent on 2024. It counted over 94.6 million alerts at the end of 2025 and nearly 365,000 hits on foreign alerts ¹³.

What happens when there is a match

A match is a lead, not proof ^9,15. Interpol says real-time results let officials detain a suspect on the spot. Where a document looks forged, police can turn to second-line forensic databases such as Edison and FIELDS ³.

For I-Checkit matches, an alert goes to the Interpol General Secretariat and the NCBs of the countries concerned. The General Secretariat coordinates follow-up, including checks on whether the person is the rightful bearer of the document ⁶. In the Schengen area, hits on foreign alerts are handled through national SIRENE Bureaux, which coordinate the exchange of information ^13,14.

The FBI says extra airport screening does not mean a person is on the watchlist. Most listed people can still fly within the US ⁹. The EU Court of Justice noted that automated PNR matching produces many false positives and requires human review of each positive result ¹⁵.

Redress: how to challenge a record

In the US, DHS TRIP is the single contact point for travellers who were denied or delayed boarding, denied or delayed at a border, or repeatedly sent to secondary screening. You apply online at trip.dhs.gov. You receive a Redress Control Number, which you can add to future airline bookings. DHS sends a final determination letter once all agencies finish their reviews ¹⁰. The FBI says most people who appeal through DHS TRIP are not on the watchlist ⁹.

For Interpol data, the Commission for the Control of INTERPOL's Files (CCF) is an independent body. It oversees Interpol's processing of personal data and handles requests to access, correct or delete data ⁷. Interpol states that any person has the right to request access to data about them in its files ⁷. From 26 March 2026, requests must go through the CCF online portal. Email and post are accepted only in exceptional cases ⁸. The CCF aims to decide access requests within four months of declaring them admissible. It issues written, reasoned decisions, and applicants can seek revision based on new facts ⁸.

• Keep boarding passes, refusal notices and the names of offices involved.
• Use any redress number you receive on future bookings ¹⁰.
• For Interpol records, apply through the CCF portal ⁸.