Serial User Protocol Coded with the Aircraft 24-Bit Address
(bits 44 to 67 and 68 to 73)

For ELTs using the serial user protocol coded with the aircraft 24-bit address, the following requirements apply:

Bits 44 - 67 provide the aircraft 24-bit address as assigned by the responsible administration in accordance with ICAO guidance in Annex 10 of the ICAO convention on Civil Aviation .
Bits 68 - 73 is a 6 bit specific ELT number, in binary notation with the least significant bit on the right, when more than one ELT is carried on the same aircraft and encoded with the same 24-bit address. When there is only one ELT with the same 24-bit address, bits 68 - 73 should all be set to "0".