Description and operation, Description, A. functional overview – ACR&Artex ME406 HM User Manual
Page 22
ARTEX PRODUCTS / ACR ELECTRONICS, INC
DESCRIPTION, OPERATION, INSTALLATION AND MAINTENANCE MANUAL
ME406 (453-6603), ME406HM (453-6604)
25-62-30
Page 22 of 84
Jun 25/13
DESCRIPTION AND OPERATION
TASK 25-62-30-870-801
1. Description
SUBTASK 25-62-30-870-001
A. Functional Overview
(1)
The ELT automatically activates during a crash and transmits the standard sweep tone on
121.5 MHz. Approximately every 50 seconds, for up to 520 milliseconds (long message
protocol), the 406 MHz transmitter turns on. During that time, an encoded digital message is
sent to the COSPAS-SARSAT Search and Rescue (SAR) satellite system.
(2)
The information contained in the message includes:
(a)
Serial number assigned to the ELT by the beacon manufacturer or the national beacon
registration authority, or
(b)
Aircraft identification or registration number, and
(c)
Country of registration and country code; plus
(d)
Position coordinates, when coupled with a navigation interface device, which receives
position data from the aircraft navigation system and transmits it to the ELT.
(3)
The 406 MHz transmitter will operate for 24 hours and then shuts down automatically. The
121.5 MHz transmitter will continue to operate until the batteries are exhausted, which is at
least 50 hours.
(4)
The 406 MHz transmitter produces a much more accurate position, typically 3 kilometers as
compared with 15 to 20 kilometers for 121.5 MHz transmitters. When coupled to the aircraft
navigation system via a navigation interface, the accuracy improves to approximately 100
meters.
(5)
The ELT transmits a digital message that allows search and rescue authorities to contact the
owner/operator of the aircraft through information contained in a database. Information
contained in the database includes:
(a)
Type of aircraft and aircraft registration number,
(b)
Owner address and telephone number, and
(c)
Alternate emergency contact.
(6)
After the ELT is activated and the 406 MHz signal is detected by the SAR satellite system and
a position is calculated, the 121.5 MHz transmissions are used to home in on the crash site.
NOTE: Effective February 1, 2009, COSPAS-SARSAT has terminated satellite processing of
distress signals from 121.5 MHz beacons.
(7)
Aircraft communications transceivers are not capable of receiving 406 MHz transmissions;
therefore, the only methods of monitoring the ELT are:
(a)
The blinking cockpit remote switch LED,