Emergency Locator Transmitter


ICAO defines an Emergency locator transmitter (ELT) as equipment which broadcasts distinctive signals on designated frequencies and, depending on application, may be automatically activated by impact or be manually activated. An ELT may take any of the following forms:

  • Automatic fixed ELT (ELT(AF)). An automatically activated ELT which is permanently attached to an aircraft.
  • Automatic portable ELT (ELT(AP)). An automatically activated ELT which is rigidly attached to an aircraft but readily removable from the aircraft.
  • Automatic deployable ELT (ELT(AD)). An ELT which is rigidly attached to an aircraft and which is automatically deployed and activated by impact, and, in some cases, also by hydrostatic sensors. Manual deployment capability is also provided.
  • Survival ELT (ELT(S)). An ELT which is removable from an aircraft, stowed so as to facilitate its ready use in an emergency, and manually activated by survivors.

An essential function associated with ELT/PLBs is provided by Cospas-Sarsat, a satellite system designed to provide distress alert and location data to national administrations with responsibility for search and rescue operations. Further information on the Cospas-Sarsat system can be viewed and/or downloaded from their web site.


ICAO requires each ELT/PLB to be uniquely coded and registered. The owner/operator of an aircraft registered in the Isle of Man is responsible for registering, or re-registering, ELT/PLBs on their aircraft with the UK Distress & Security Beacon Registry who are the Isle of Man and UK point of contact for ELT/PLB registrations.

All 406 MHz ELT/PLBs should be registered with the UK Distress and Security Beacon Registry, even if not fitted to an aircraft. Many ELT/PLBs are inadvertently activated when in storage or in transit and such false alerts can initiate search and rescue action if the owner cannot be identified and questioned.

It is vitally important that points of contact 24 hour telephone numbers are provided when registering the ELT/PLB and that the UK Distress and Security Beacon Registry is informed as soon as possible of any changes to the points of contact or telephone numbers.

Registration is accomplished by completing the Isle of Man Aircraft Registry's Form 37, and sending the completed form by e-mail (please copy in [email protected]), fax or post to UK Distress & Security Beacon Registry at the address shown below:

UK Distress & Security Beacon Registry
Falmouth MRCC
Pendennis Point
Castle Drive
TR11 4WZ
United Kingdom

Tel +44 (0)20 3817 2006
Fax +44 (0)1326 319264

E-mail - [email protected]

An overview is that:

  • a survival or automatic ELT is required whilst flying on any flight at a distance of more than 10 minutes flying time at normal cruising speed away from land suitable for making an emergency landing;
  • an automatic ELT is required whilst flying over areas which have been designated by the State concerned as areas in which search and rescue would be especially difficult.

Further details can be found in Schedule 3.4 Table and in Scale KK of the Air Navigation (Isle of Man) Order 2015 as amended. 

ICAO recommends that each ELT/PLB is assigned a unique identification code and this is provided by a 15 character Hexadecimal ELT/PLB identification (15 HEX ID) code. It must be UK-coded and begins with 1DO or 9DO. If it is a GPS-integrated, location protocol ELT/PLB, the default 15 digit code is required, i.e. not containing position information, so it should normally end with FFBFF or 81FE0.

ICAO has defined five coding options which can be used and each ELT/PLB digital message is required to contain information from one of these coding options as shown in the table below. All aviation coding methods include a country code which, for the Isle of Man and UK, is 232.

Available coding options for user protocols
1 Unique Serial Number of ELT
2 Aircraft Operator Designator and Operators Serial Number
3 Aircraft Registration Mark
4 Isle of Man issued 24-bit Mode S Aircraft Address
5 Serial Number of PLB

Note: The 24-bit Mode S Aircraft Address is issued to an aircraft by the Isle of Man Aircraft Registry on receipt of an application for registration.

The ELT/PLB digital message shall contain information relating to the message format, coding protocol, country code, identification data, and location data as appropriate.

For ELT/PLBs with no navigation data provided, the short message format, Cospas-Sarsat Technical document T.001 shall be used, making use of bits 1 through 112. For ELT/PLBs with navigation data, if provided, the long message format shall be used, making use of bits 1 through 144.

The ELT/PLB make and model number will have been assigned a Cospas-Sarsat Beacon Type Approval Certificate (CSTA) number. This number can also be found on the Cospas-Sarsat website using the Beacons tag.