Home' RTCA Documents for Review : C2 Link Systems MASPS_Draft Contents Appendix D
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OPA for Remote Pilot’s Navigate Activity
“Navigate” activities involve the remote pilot’s interaction with the UA’s navigation
systems. Those Navigation activities include the information exchanges between the CS
and UA. These exchanges consist of the following:
1. Initial uploading of the route of flight into the navigation system (this action is
completed before takeoff).
2. Changes to the route of flight while the UA is airborne.
3. Confirmation messages from the UA to the CS following uploading of a flight plan or
from changes to the route of flight.
4. Navigation-related position information from the UA navigation sensor(s) to the CS.
5. Navigation system status information from all the navigation sensors on UA.
This Subsection describes the development of the operational performance requirements
to support OR-1.3 and OR-2.4 using the Linear Sensing and Aerial Survey CONOPS and
the specific scenarios and Use Cases C2-S1-UC4.3, C1-S1-UC1.2 and C2-S1-UC4.6 as
described in APPENDIX B in the OSED and the results are summarized in Table E-4.
In the latency estimates in Subsection E.2 of this Appendix, it was determined that a latency
of 1.0 second for the entire C2 Link System could be achievable. This latency tolerance
supports the feasibility of the C2 Link System to include both satellite -based links as well
as networked terrestrial links having multiple GRS. Since the updates to position based on
GPS typically occurs every second, a latency of 1.0 second would not materially affect the
remote pilot’s Navigate activities described above.
Short C2 Link System Interruptions
For the purposes of this section, a short interruption is defined as any interruption that does
not exceed the TET for the C2 Link System. There is no time criticality for completing the
initial uploading of route of flight messages to the UA since the aircraft is in pre -flight
status. The aircraft can remain on the ground until the upload of the messages and
confirmation of acceptance is received.
The time criticality for changes to the route of flight while the UA is airborne will depend
on how far in advance the remote pilot needs to change the flight plan before the UA must
change course. The most time-critical situation for a navigation message would be a flight
plan change required by ATC. In controlled airspace, this will depend on how far in
advance the controller issues instructions to change the route of flight. However, any short
interruption of a navigation message could be compensated for by the remote pilot
performing Aviate activities until the competition of the sending of the navigation
messages and acknowledgment of receipt has occurred. If needed, the navigation message
could be resent. The remote pilot is required to change the route of flight in a timely
manner when directed by ATC. If the remote pilot chooses to comply by sending a flight
plan change to the UA, the Navigate information exchanges would have to occur on the
same timeline as the remote pilot’s Aviate activity timeline. The remote pilot will have to
judge if time is available to input navigation commands before the controller calls to
question the timeliness of the UA’s maneuvers.
For example, in CONOPS 2, Scenario 2, the controller instructs the remote pilot that they
are “cleared to maneuver between ‘BUBBS and GROVE’.”
The remote pilot
acknowledges the controller’s instructions and then sends a revised plan to the navigation
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