Home' RTCA Documents for Review : DO-262D Contents Appendix E
© RTCA, 2018
SDM, while other details are left to the individual manufacturers. These details are
outside the minimum requirements of this appendix.
The system is designed to make this switching between networks near-seamless.
ACARS and voice services remain available. The Classic Aero networks do not
support ATN/OSI, ATN/IPS and IP services.
This appendix deals only with the performance requirements for an SBB
AES. The performance requirements of the AES in Classic Aero mode
are outside the scope of this appendix, but are covered in DO-210D.
Iridium AMS(R)S On The Same Aircraft
The minimum performance standards contained in this appendix are intended to
assure proper operation of Inmarsat priority services on all aircraft, and compatibility of
such services with other communication, navigation, and surveillance radios operating
on the same aircraft and in the same airspace. A significant caveat to this intent is the
ability to support simultaneous independent operation of both Iridium and Inmarsat
AESs on the same aircraft without a demonstrated means of cooperation. Owners,
operators and installers are cautioned that simultaneous independent operation of
Inmarsat and Iridium AES equipment on the same aircraft has the potential to cause
significant interference to all Iridium AMSS and AMS(R)S services on that aircraft.
This caution applies to Inmarsat equipment that is compliant with RTCA DO-210D,
including all changes, ARINC Characteristic 741, ARINC Characteristic 761, ARINC
Characteristic 781, and any AES complying with this appendix. At the time of
publication of this appendix, simultaneous independent operation of Inmarsat and
Iridium equipment on the same aircraft had been reported in special cases. However,
no generally applicable and technically feasible means of mitigating the potential for
interference could be identified.
This caveat specifically excludes installations where Inmarsat and Iridium are intended
for use in a non-simultaneous mode of operation. For example, no special installation
or other considerations are required for Iridium use in polar airspace that is outside of
the coverage volume of the Inmarsat services described in this appendix.
At the time of publication of this appendix, there is no regulatory guidance nor
AMS(R)S operational need to require Inmarsat and Iridium systems to work
simultaneously on the same aircraft. Some operators may choose to use Iridium and
Inmarsat as backup or in a non-simultaneous mode of operation.
Iridium AMS(R)S In The Same Airspace
The caveats of the previous paragraph apply to simultaneous independent operation
of Inmarsat and Iridium AMS(R)S or AMSS on the same aircraft. ICAO Aeronautical
Communications Panel, Working Group M in 2008 accepted analyses indicating that
Inmarsat safety and non-safety communication services do not induce harmful
interference to Iridium AMS(R)S equipment on other aircraft operating under 30/30
nautical mile separation in procedural airspace. Appendix C to Attachment 1 of the
DO-343 / ED-242 MASPS contains an interference model appropriate for establishing
interference effects between Inmarsat safety and non-safety communication services
with Iridium AMS(R)S equipment on other aircraft operating in continental airspace.
The conclusion of that model is that the interference impact of Inmarsat on Iridium
Block 1 equipment is negligible.
Future Iridium system upgrades will be subjected to the interference
model referenced above.
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