Search-and-rescue teams combine the aircraft’s last reported position, any distress-tracking updates, and alerts from emergency locator transmitters (ELTs). Satellites can detect and help locate a 406 MHz distress beacon, while aircraft distress data may also be shared through ICAO’s Location of an Aircraft in Distress Repository (LADR). Rescue coordination centers use those clues to organize the maritime response. The result is a progressively refined search area—not necessarily an immediate, exact crash location.
What information can reveal an aircraft’s location?
There is no single tracking system that serves every purpose. Rescuers may have ordinary flight-position reports, position updates generated during a distress event, or an ELT alert after a beacon activates. Which clues exist depends on the aircraft’s equipment, the circumstances, and whether data reaches the relevant organizations.
| Source | When it provides information | What it contributes |
|---|---|---|
| Aircraft tracking | During normal operations | Automated position reports that help establish the last known track. |
| Autonomous distress tracking (ADT) | During a distress event, for aircraft equipped and subject to applicable requirements | Position-determinable information intended to help locate an aircraft in distress. |
| Emergency locator transmitter (ELT) | After activation; some systems can activate before impact under preset conditions | A beacon alert, including a 406 MHz signal that satellite systems can detect and locate. |
These sources are complementary, not interchangeable. A normal-flight report may be the most recent clue available without being the aircraft’s final position; distress tracking can add updates during an emergency; and an ELT may provide a beacon location after activation.
How does a last known position become a search area?
1. Reconstruct the aircraft’s last reported track
Rescuers and investigators can draw on aircraft tracking reports and information held by the operator or air traffic services. ICAO describes aircraft tracking as automated four-dimensional position reporting—latitude, longitude, altitude, and time—at intervals of 15 minutes or less. That is a normal tracking description, not a guarantee of continuous coverage or the distress-update rate.
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A last report is a time-stamped clue, not necessarily a crash coordinate. The aircraft may have continued moving after it was recorded, and a loss of contact does not by itself show exactly what happened or where.
2. Look for position updates during distress
Autonomous distress tracking is intended to provide position information when an aircraft is in distress. For the specified aeroplanes covered by ICAO guidance, the requirement is to transmit position-determinable information at least once per minute during distress. ICAO also describes ELT(DT) systems that can activate in flight when preset conditions indicate imminent danger, allowing distress information to be sent before impact.
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The rule is not universal. The stated requirement applies from 1 January 2025 to aeroplanes over 27,000 kg whose individual certificate of airworthiness was first issued on or after 1 January 2024. Whether a particular aircraft is equipped or covered depends on its circumstances and applicable rules.
3. Detect an activated 406 MHz beacon
ICAO describes Cospas-Sarsat as a satellite-based system for detecting and distributing distress alerts. When an equipped ELT transmits a 406 MHz alert, the satellite and ground network can process alert and location information and pass it to search-and-rescue authorities. ICAO-hosted technical material describes the MEOSAR component as providing near-real-time worldwide coverage and independent beacon location.
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Frequency matters. ICAO says ELTs typically transmit on 121.5 MHz and 406 MHz, and some also transmit on 243 MHz. The global Cospas-Sarsat system cannot detect 121.5 MHz or 243 MHz beacons. On some ELTs, a 121.5 MHz signal instead serves as a local homing signal that nearby search assets can use after an alert has brought them to the general area. It is not the satellite alert channel.
4. Check whether distress data is available through LADR
ICAO’s LADR is a central repository designed to make position information from autonomous distress-tracking systems available to appropriate organizations designated by the operator’s state. It helps stakeholders find distress data; it does not dispatch ships or aircraft, coordinate the rescue, or guarantee that data for every aircraft is present.
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In a November 2025 announcement, ICAO said ADT data from aircraft worldwide was being fed into LADR through a connection involving EUROCONTROL and the French Mission Control Centre. That describes the deployment reported at that time, not a guarantee of current or complete coverage.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Who coordinates the maritime search?
Alert and position data must reach the search-and-rescue organizations responsible for the relevant maritime area. Rescue coordination centers use available information to organize the response and, where needed, coordinate with participating assets and neighboring authorities. The IMO’s SAR Convention provides a framework for coordination and cooperation between national SAR organizations.
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LADR is an information-sharing resource within that larger chain; rescue organizations—not the repository—coordinate operational responses. The general international framework does not identify which center led a particular incident, which ships or aircraft took part, or what search pattern was chosen. Those details require records from the relevant authorities.
Why the exact location may remain uncertain
The quality and timing of the available clues shape how narrowly teams can focus a search. A position report may precede the loss of contact; distress updates depend on equipment and data availability; and a beacon alert depends on activation and successful detection and routing. Even a reported beacon location is not proof that every other location estimate matches it.
- Different systems serve different moments: routine tracking, in-flight distress tracking, and a post-activation beacon alert are separate paths.
- Equipment and data access vary: not every aircraft has the same systems, and LADR does not guarantee that every aircraft’s distress data is available.
- Incident details need incident-specific evidence: general ICAO and IMO system descriptions cannot establish a particular aircraft’s final track, search geometry, duration, or outcome.
ELT maintenance is part of the aircraft maintenance program, and accidental activation can generate a false SAR alert. Handling and testing must follow the applicable aircraft procedures rather than casual activation.
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