Home' RTCA Documents for Review : C2 Link Systems MASPS_Draft Contents Appendix D
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OPA for the Remote Pilot’s Aviate Activity
The remote pilot’s activity of “Aviate” describes the ability of the remote pilot to interact
with the Flight Guidance System and other onboard equipment that measures or modifies
aircraft flight parameters and system status; all these help enable the pilot to operate the
UA safely. This type of remote pilot interaction includes all actions to ensure the UA
remains in stable flight and to maneuver the aircraft directly (as opposed to maneuvers
caused by modifying the flight plan in the Flight Management System) in response to
information provided by the DAA system, the optional collision avoidance system or ATC
instructions. This Subsection describes the development of the performance requirements
to support OR-1.1 using the Linear Sensing and Aerial Survey CONOPS and the specific
scenarios and use cases as described in B.8.1 in the OSED and listed in Table E-2 of the
introduction to this Appendix.
Note D-18: The latency estimate for the support of the Aviate activity assumed that the UA
was equipped with a Flight Guidance System so that the C2 Link System’s
latency was not part of the inner-loop control of the UA’s trajectory, i.e., this
MASPS assumes the C2 Link System does not support the remote pilot’s direct
control of the UA’s aerodynamic surfaces.
Results from the OSA indicated that three types of use cases were the most demanding and
were consequently used when developing the C2 Link System’s RLTP to support the
remote pilots Aviate activity in this OPA.
Type 1. Remote pilot’s telecommand to maneuver the UA as directed by the DAA
system was interrupted for longer than acceptable such that an inadequate or lack of
maneuver occurred when one was required was assessed as Catastrophic in both Use
Case C1-S1-UC3.2 and Use Case C1-S1-UC6.2 (see the HAW in Annex A to
APPENDIX C) and the OV-3 (see B.7.5 within the OSED).
Type 2. Remote pilot receiving undetected corrupted UA status information was
assessed, in the OSA, as Hazardous in Use Case C2-S1-UCA1.6b.
Type 3. Remote pilot’s telecommand to enter a new heading into the Flight Guidance
System, in response to an already acknowledged controller’s instruction, does not get
received by the UA because of a C2 Link System interruption that was longer than the
acceptable; such an interruption was assessed, in the OSA, as Major in Use Case C1-
Although from the perspective of C2 Link System interruptions, Type 1 situations, because
of their higher catastrophic severity due to the possible loss of DAA Well Clear, may
appear to be more demanding than Type 3. Type 3 situations occur much more frequently
so could require a higher C2 Link System Availability and Continuity. Controller re-
directions, which Type 3 represents, are routine and it is most important for the remote
pilot to be able to make such Aviate related changes to the UA flight in a timely and reliable
manner. Consequently, both Type 1 and Type 3 situations were used as the basis for the
OPA Availability and Continuity analysis as seen in the following sections.
The Type 2 situation, which is based on a corrupted data hazard in the HAW was used to
determine the Integrity requirements for the C2 Link System when supporting the remote
pilot’s Aviate activity.
The latency requirement for the C2 Link System, when supporting the remote pilot’s
Aviate activity, has already been derived, in Subsection E.2 of this OPA Annex, as not to
exceed 1 second. In the following sections, this one-second latency will be used.
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