When flying in remote areas, there is no better precaution than to plan your trip well and let someone know where you are going and when you expect to return. In the (hopefully) unlikely event that you did somehow manage to get yourself stuck or lost, the following is a quick reference guide to the most common signals that will be useful in the event of an air search.


Ideally construct these signals on high ground using fabric, rocks or logs that contrast in colour with the ground. (They should be at least 3m in size).

Additional useful AIR SEARCH SIGNALS:

K : indicates the direction to proceed
I : serious injuries, send doctor
II : send medical supplies
X : unable to proceed
F : need food and water
<-- : travelling in this direction
(triangle) : should be safe to land here
(square/rectangle): require map and compass
L : need fuel
LL : all is well
N : no
Y : yes
JL : not understood

AIR to GROUND SIGNALS:

If your message has been understood, the pilot will
- rock the plane's wings from side to side (day) or
- flash a green light (night)
- flashing on and off twice landing lights or navigation lights (night)

If your message is SEEN but NOT been understood, the pilot will
- makes a right-hand circle or flashes a red light

If your message is NOT understood, there will be lack of any of above signals

Asia SAR Agencies & Coordination:

SAR in Singapore
SAR in Australia

There are three types of beacons used to transmit distress signals, EPIRBs (for maritime use), ELTs (for aviation use), and PLBs (used for land-based applications).

Beacons are designed to transmit to satellites on either 121.5 or 406 MHz, although the 121.5 MHz beacons are now only used by the aviation community, and are being phased out. 406 MHz beacons can and should be registered. If for some reason a beacon activates inadvertently and it is registered, rescue authorities can contact the owner and possibly avoid a costly and risky search. More importantly, registration will help rescue forces find persons in distress faster in an emergency.

One common feature of all beacons is that in addition to their distress alerting signals, they transmit a low-power continuous 121.5 MHz signal that rescue units can home on to precisely locate them.

Some beacons are referred to as location-protocol beacons. The 406 MHz distress beacon message contains a beacon identification number, which is used by SAR personnel to identify a beacon owner and to initiate a preliminary location investigation. Approximately 30 percent of existing beacons incorporate a GPS navigation signal receiver into their design. These “location protocol” beacons can transmit their precise geographic location in addition to an identification number.

Emergency Position-indicating Radio Beacons (EPIRBs)

All authorized EPIRBs now operate on 406 MHz. The 406 MHz EPIRBs are divided into two categories. Category I EPIRBs are activated either manually or automatically. The automatic activation is triggered when the EPIRB is released from its bracket. Category I EPIRBs are housed in a special bracket equipped with a hydrostatic release. This mechanism releases the EPIRB at a water depth of 3-10 feet. The buoyant EPIRB then floats to the surface and begins transmitting. If you own a Category I EPIRB, it's very important that you mount it outside your vessel's cabin where it will be able to "float free" of the sinking vessel.

Category II EPIRBs are manual activation only units. If you own one of these, it should be stored in the most accessible location on board where it can be quickly accessed in an emergency.

A 406 MHz EPIRB signal can be instantly detected by geostationary satellites. This means that even a brief inadvertent signal can generate a false alert.

Emergency Locator Transmitters (ELTs)

Different types of ELTs are currently in use. There are approximately 170,000 of the older generation 121.5 MHz ELTs in service. Unfortunately, these have proven to be highly ineffective. They have a 97% false alert rate, activate properly in only 12% of crashes, and provide no identification data. To fix this problem 406 MHz ELTs were developed to work specifically with the Cospas-Sarsat system. These ELTs dramatically reduce the false alert impact on SAR resources, have a higher accident survivability rate, and decrease the time required to reach accident victims by an average of 6 hours.

General aviation aircraft must carry either a 121.5 MHz ELT or a 406 MHz ELT. One government study concluded that 134 extra lives and millions of dollars in SAR resources could be saved per year if these aircraft switched to 406 MHz ELTs, although these more effective ELTs cost more. For a comparison of 121.5 and 406 MHz beacons, see http://www.sarsat.noaa.gov/406vs121.pdf. Most ELTs are designed to survive and activate automatically in a crash.

Personal Locator Beacons (PLBs)

PLBs are portable 406 MHz units that operate basically the same as EPIRBs or ELTs, but are designed to be carried by an individual person instead of on a boat or aircraft. The number of these beacons in use has grown rapidly since they were authorized in July 2003. They can only be activated manually.

Cospas-Sarsat system

The newest search and rescue system is the Cospas-Sarsat system. It is an international search and rescue system made up of a network of satellites in space, and control centres on Earth-ground stations, mission control centres, and rescue coordination centres. The Sarsat system was developed in a joint effort by the United States, Canada, and France. The Cospas system was developed by the Soviet Union. These four nations banded together in 1979 to form Cospas-Sarsat. In 1982, the first Cospas-Sarsat satellite was launched, and by 1984 the system was declared fully operational.

From there, the Cospas-Sarsat organization continued to grow. The four original member nations have now been joined by 25 other nations that operate 28 ground stations and 15 mission control centres worldwide. In the eyes of the countries using this system, Cospas-Sarsat has very much helped search and rescue efforts.

The Cospas-Sarsat system is able to monitor the entire world because of the series of low-altitude satellites in near-polar orbits. By working together, the satellites provide complete coverage of the Earth, including the polar regions.

Anywhere on Earth, a user can activate an emergency beacon to signal distress. When the emergency beacon is activated, the signal is received by a Cospas-Sarsat satellite and relayed to the nearest available ground station. The ground station, called a Local User Terminal (LUT), processes the signal and calculates the position of the distress signal. This position is sent to a mission control centre where it is joined with identification data and other information on that beacon. The mission control centre then informs a rescue coordination centre nearest the beacon that is sending out the distress signal. If the beacon is in another country's service area, then the alert is transmitted to that country's mission control centre. The Cospas-Sarsat beacons are emitting a signal of frequency 406 MHz, and with these beacons a distress signal can be sent from anywhere on Earth 24 hours a day, 365 days a year.

Each satellite in the Cospas-Sarsat system makes a complete orbit of the Earth around the poles in about 100 minutes, travelling at a velocity of seven kilometres per second. The satellite views a region of the earth over 4000 km wide as it circles the globe, giving it a field of view, at any one time, the size of a continent. When viewed from the earth, the satellite crosses the sky in about 15 minutes.

All of the polar orbiting satellites in the Cospas-Sarsat system carry a Search and Rescue Repeater (SARR) which receives and retransmits 121.5 MHz and 243 MHz signals any time the satellite is in view of a ground station. After amplification and frequency conversion, the signals are retransmitted on the 1544.5 MHz downlink. Automatic Level Control (ALC), a feature of the repeater, is provided to maintain a constant output level. The SARR is a project of the Canadian Department of National Defence.

The satellites involved in the Cospas-Sarsat system carry equipment specific to their function as search and rescue spacecrafts. This equipment consists of a 121.5 MHz repeater unit on Cospas satellites and a 121.5, 243 and 406 MHz repeater unit on Sarsat satellites, designed for retransmission of distress signals in the local coverage mode. There is a receiver-processor and memory unit on Cospas and Sarsat satellites designed to receive, process and store signals received on 406 MHz for retransmission in the local and the global coverage mode. Its purpose is to demodulate the digital messages received from beacons, to measure the received frequency, and to record the time the measurement was taken.

For more information on distress beacons, visit www.sarsat.noaa.gov

Standby. Information coming soon!

Standby. Information coming soon!