Home' RTCA Documents for Review : C2 Link Systems MASPS_Draft Contents Appendix B
© 2018 RTCA, Inc.
This scenario provides seven use cases that allow the assessment of the C2 Link system
performance requirements for various phases of flight and allows detailed ex amination of
several UAS flight crew activities. These use cases are:
1. Pre-flight to takeoff at Class D airport (Pre-flight/Takeoff).
2. Climb and transit to filed route over highways (Departure).
3. Switchover from local terrestrial to area terrestrial C2 Link (Terrestrial → Terrestrial).
4. Diversion from filed flight plan to transit to traffic accident (Reroute).
5. Return flight to Class D airport (Arrival).
6. Switchover from area terrestrial to local terrestrial C2 Link (Terrestrial → Terrestrial).
7. Approach, landing, and post-flight activities (Landing/Post Flight).
Use cases 1 and 7 provide opportunities to examine operations in a VFR airport
environment with an FAA ATC control tower. Use Case 3 provides the opportunity to
examine in detail the C2 Link System requirements for the remote pilot’s interaction with
the navigation systems used by the UAS. Use Cases 2 and 6 provide an opportunity to
examine link switchovers between terrestrial links.
The following subsections describe each of the Use Cases.
Use Case 1 Pre-flight/Takeoff
The remote pilot begins the operation by filing a flight plan with FAA Flight Service and
conducts any pre-coordination required by the LOA with TRACON via telephone. The
CS, located remotely from the airport, (see Figure C-4) is powered up and connected via a
secure landline to a local C2 ground station. This terrestrial link ground radio systems
(GRS) is located at the airport to provide a radio line of sight link until the UA comes into
view of the area terrestrial link. The area terrestrial link GRS is on a radio tower located
to provide radio LOS service throughout the representative metro area shown in Figure C-
The remote pilot establishes voice communications via telephone with the ground crew at
the airport where the UA is stored. The ground crew powers up the UA and the pre-flight
checklist performed by the remote pilot in coordination with the ground crew. The ground
crew tows the UA to the designated helipad and notifies the remote pilot that the UA is
ready for takeoff.
The remote pilot confirms that both terrestrial links are ready to control the UA as part of
the pre-flight activities. The remote pilot uses the C2 Link System to load the route as
approved by ATC into the FMS of the UA.
The remote pilot commands the UA VHF Radio to tune the Class D Tower frequency and
contacts tower controller for ATC clearance. Tower controller relays ATC clearance from
the TRACON to remote pilot and assigns a transponder code. The remote pilot enters the
transponder code assigned by ATC into the UA Transponder. The remote pilot contacts
tower for departure clearance using VHF radio on UA. The tower controller clears the UA
to takeoff and assigns an altitude and direction to depart the Class D airspace. The remote
pilot starts the UA’s engine and commands the FGS to takeoff and climb to the assigned
altitude. Once the UA has cleared the ground and nearby obstacles, the remote pilot
commands the FGS to fly the cleared departure direction.
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