Home' RTCA Documents for Review : C2 Link Systems MASPS_Draft Contents Appendix D
© 2018 RTCA, Inc.
C) hazard that cannot consequently occur, based on (see Table E-1), more than one in one
hundred thousand transactions, the C2 Link System Status Reporting Continuity must also
be better than 99.99% for a Risk Class 3 UAS.
Integrity of the C2 Link System Status Reporting
For Use Case C1-S1-UC4d the OSA determined the severity of the delivery of misleading
C2 Link System Status Reporting information to be Hazardous (see the HAW in Annex A
to APPENDIX C) so the C2 Link System Status for our example aircraft, reporting must
be designed to a DO-254 , DO-178  and DO-278  Design Assurance Level
appropriate to this Major severity for this failure mode. For a Risk Class 3 UAS, this is
Considerations on the C2 Link System’s Support of the Status Reporting Aspects of
the Support of the Remote Pilots Mange C2 Link Activity
C2 Link System designer Subject Matter Experts also determined that the C2 Link System
Status Reporting should not only report on the quality of the signals received at both ends
of the C2 Link System, as described above but also report on two additional metrics. The
first additional metric is the power of the transmitted signal going into the GRS or GES
and ARS or AES antenna and the second is any miss-pointing of any steerable beam
Although these two metrics are not required to provide an accurate statusing of the C2 Link
System’s performance, they will help in any post-incident analysis.
Additionally, since there is a high degree of likelihood that, to protect other services sharing
the spectrum used by the C2 Link System, UA transmissions may have to be interrupted if
steerable beam antennas are miss-pointing (e.g., the FCC’s rules  on Earth Stations In
Motion require cessation of transmission within 100 ms if the antenna miss-points enough
to cause unacceptable levels of interference into adjacent satellites , the C2 Link System
Status Reporting report on antenna pointing errors for systems with steerable antennas will
C2 Link System Switchovers - Supporting FR-2.3
As discussed in more detail in APPENDIX E, Switchovers can be categorized into those
that are Scheduled as part of the flight planning process prior to takeoff and those that are
Unscheduled. The need to perform an Unscheduled switchover is not predictable and can
arise at any time during the flight operation because of, for example, equipment failure or
unacceptable degradation of the QoSD on the link or network being used.
APPENDIX E also identifies two switchover mechanisms for both Scheduled and
Unscheduled Switchovers namely, Break before Make (BbM) and Make before Break
(MbB). As described in APPENDIX E, failure of a BbM Switchover results in the link
that was being used continuing to be used until a new link has been established. However,
failure of a BbM Switchover results in a Lost C2 Link state.
From an OPA perspective the performance metrics for both types of Switchover are the
same, namely the acceptable probability of occurrence of a:
1. Failed Switchover or of a
2. Misdirected Switchover.
However, the RLTP may be different depending on the category (Scheduled or
Unscheduled) of the Switchover or the mechanism (BbM or MbB) employed.
Links Archive DO-XYZ_ED-ABC_FRAC_SC236_MASPS Navigation Previous Page Next Page