ACR&Artex C406-2 HM - Manual (Page 26)

ACR ELECTRONICS, INC / ARTEX PRODUCTS
DESCRIPTION, OPERATION, INSTALLATION AND MAINTENANCE MANUAL
C406-2 (453-5000), C406-2HM (453-5001)
25-62-11
Page 26 of 87
JUN 20/13
DESCRIPTION AND OPERATION
TASK 25-62-11-870-801
1. Description
SUBTASK 25-62-11-870-001
A. Functional Overview
(1) The ELT automatically activates during a crash and transmits the standard sweep tone on
121.5 and 243.0 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 an ELT/NAV Interface (453-6500). Refer to the
ELT/NAV Interface Abbreviated Component Maintenance Manual (570-4602) for a
detailed discussion of the interaction between the ELT, ELT/NAV Interface, and aircraft
navigation system.
(3) The 406 MHz transmitter will operate for 24 hours and then shuts down automatically. The
121.5/243.0 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 121.5/243.0 MHz transmitters. When coupled to the