Home' RTCA Documents for Review : DO-204B, MOPS Aircraft ELT 406MHZ Contents © EUROCAE, 2018
1.3 TYPES, CLASSES, CAPABILITIES AND APPLICABILITY OF ELT
This MOPS was created to permit ELT manufacturers, users, installers, operational
and airworthiness authorities to determine the specifications of ELTs. These
specifications are defined by introducing ELT types, classes and capabilities, that the
ELT manufacturer must document in the installation manual and Declaration of Design
and Performance (DDP).
Types of ELT
Five basic types of ELT are described in this document. They are: Automatic Fixed
(ELT(AF)), Automatic Portable (ELT(AP)), Automatic Deployable (ELT(AD)), Distress
Tracking ELT (ELT(DT)) and Survival (ELT(S)). The type of ELT implies the
compliance to a certain set of specifications from this document. The header of the
subsection or the text of the specification may identify the ELT type(s) it applies to. If
no type is identified, the specification applies to all ELTs.
An Automatic ELT as referenced in the ICAO SARPS is either an ELT(AF), ELT(AP),
or ELT(AD). For these ELTs, the term automatic is used to identify ELTs which have
the capability to determine that a crash or a ditching has occurred and either activate
or deploy as required.
The five basic types of ELTs are described below:
Automatic Fixed (ELT(AF))
This type of ELT is intended to be permanently attached to the aircraft before and after
a crash, to automatically activate upon a crash, and is designed to aid SAR teams in
locating a crash site and/or survivor(s).
Automatic Portable (ELT(AP))
This type of ELT is intended to be rigidly attached to the aircraft before a crash, to
automatically activate upon a crash, but is readily removable from the aircraft after a
crash. If the ELT does not employ an integral antenna, the aircraft-mounted (external)
antenna may be disconnected and an auxiliary antenna (stored on the ELT case)
connected in its place. After removal from the aircraft, the ELT can be tethered to a
survivor or a life raft. This type of ELT is intended to aid SAR teams in locating a crash
site and/or survivor(s).
Automatic Deployable (ELT(AD))
This type of ELT is intended to be rigidly attached to the aircraft before a crash or
ditching and automatically deployed when a crash occurs or after activation by a water
sensor. This type of ELT also operates while floating in water and is intended to aid
SAR teams in locating a crash site and/or survivor(s). The ELT(AD) may be either a
stand-alone beacon or may be a part of an Automatic Deployable Flight Recorder
Distress Tracking (ELT(DT))
This type of ELT is designed to be activated prior to a crash upon detection of a
distress condition by logic such as that defined by EUROCAE MASPS ED-237. This
type of ELT is intended to provide information prior to the crash to aid in locating a
crash site and/or survivor(s).
This type of ELT is intended to be removed from the aircraft after a crash and
activated manually by survivors or automatically with the deployment of other survival
equipment. There are two categories of ELT(S), Category A which is buoyant and
designed to operate when floating in water and Category B which is not designed to
operate when floating in water. This type of ELT is intended to aid SAR teams in
Three operational temperature classes of ELTs (Classes 0, 1 and 2) are described in
§ 4.2.1 and are consistent with the Cospas-Sarsat specifications.
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