Factual Information 2015:1.6 Aircraft Information/1.6.6 ELT
This page contains an extract from MH370/01/15 Factual Information which accompanied the (first) Interim Statement released by The Malaysian ICAO Annex 13 Safety Investigation Team for MH370 on 8th March 2015.
1.6.6 Emergency Locator Transmitter (ELT)
An ELT is a radio beacon that when activated will transmit digital distress signals. These signals can be tracked in order to aid the detection and localisation of an aircraft in distress.
The Fixed and Portable ELT radio beacons interface worldwide with the international Cospas-Sarsat satellite system for Search and Rescue (SAR). When activated and under satellite coverage, such beacons send out a distress signal which can be detected by satellites. The satellite receivers send this information to ground stations. This signal is transmitted to Mission Control Centres (MCC) located in six regions worldwide. The MCC covering the Indian Ocean is managed by the Australian Maritime Safety Authority based in Canberra, Australia.
ELTs are mandatory safety items carried on board the aircraft. The cabin and the technical crew attend compulsory safety emergency procedure (SEP) training and have to remain current by attending refresher SEP courses. Operation and functioning of the ELT is part of the SEP training module.
The specifications for the ELT are contained in FAA Technical Standard Orders TSO-C126 and TSO- C91A.
The ELT is a radio beacon; like all other radio equipment installed on-board, its usage is approved by the Malaysian Communications and Multimedia Commission through the Aircraft Radio Licence.
(Appendix 1.6C - Copy of the Radio Licence issued for 9M-MRO).
9M-MRO had four ELTs installed. They were located as follows:
One FIXED ELT located above ceiling of the aft passenger at STA 1880.
The aircraft was delivered without a fixed ELT; this component was added by MAS later (between December 2004 and July 2005).This unit is mounted to aircraft structure at the aft passenger cabin at STA 1880. A control switch installed in the cockpit aft overhead panel provides the command signal. This switch is guarded in the ARMED position. If required the flight crew can select the ELT to ON by moving the guarded switch from ARMED to ON.
The fixed ELT is manufactured by ELTA FRANCE and is of the 406 series, part number is 01N65900. The unit is connected to an omni-directional, triple frequency blade antenna located at the rear fuselage forward of the vertical stabilizer at station 1881. The ELT will activate upon a sudden deceleration force per the Technical Standard Order. This ELT has the provision to operate on the satellite frequency of 406 MHz when activated. The transmission includes the ELT identifier, aircraft nationality and registration markings. It will also transmit on 121.5 MHz and 243 MHz when activated and these signals may be detected by air, sea or ground receivers. Transmissions on VHF frequency (121.5/243 MHz) are line of sight and effective only in close proximity.
The battery expiry date for the FIXED ELT was November 2014.
One PORTABLE ELT located in the forward cabin right hand coat closet. This closet is used by the cabin crew. This unit is bracket-mounted to the inside of the coat closet door. A label fixed on the coat closet door identifies the ELT. The installation allows quick removal. The Portable ELT is manufactured by ELTA FRANCE and is of the 406 series. It is identical to the fixed ELT except that this unit has its own foldable antenna. The operations and function are the same. The manufacturer part number is 01N65910. The portable ELT has a control switch on the front face. It is normally in the OFF position. When needed, the crew can select the switch to the ON position to activate the ELT transmission.
The battery expiry date for the PORTABLE ELT was November 2014.
Two SLIDE RAFT mounted ELTs are packed within the slide raft assembly located at Door 1 Left and Door 4 Right. The slide raft mounted ELT will only be available when the slide rafts at doors 1 Left or 4 Right are deployed. The ELT transmission is not satellite enabled. The transmission signal is on 121.5 MHz and 243 MHz which may be monitored with air, sea and ground-based receivers.
The slide raft ELT is automatically armed when the slide raft is deployed and inflated. Once armed the ELT is automatically activated by a water sensor coming in contact with water. This ELT is not activated by deceleration. The slide raft ELTs (Part No.: P3-03-0029-10) are manufactured by DME Corporation and the battery expiry dates are as follows:
Door 1 Left - August 2016
Door 4 Right - May 2017
Source: Malaysian ICAO Annex 13 Safety Investigation Team for MH370, 8 March 2015, Factual Information MH370/01/15
The Factual Information was updated in 2018 by the Safety Investigation Report MH370/01/2018 which added new content but did not include all of the previous data.