Home' RTCA Documents for Review : C2 Link Systems MASPS_Draft Contents Appendix A
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The requirement to DAA other aircraft may drive the requirements for the C2 Link System
when the aircraft is operated in airspace with other air traffic operating not und er positive
control. If the sensor(s) for detecting proximate aircraft are installed on the UA, the C2
Link System is required to deliver that data to the CS so that the remote pilot can act on
the information in a timely manner. The link is critical for enabling the remote pilot to
initiate maneuvers to remain well clear of other aircraft and to observe the other right of
way rules. C2 Link System requirements could be lowered if the UA is equipped with a
flight guidance system that is certified to execute avoidance maneuvers without
intervention by the remote pilot. However, the design assurance requirements that the FAA
would apply to this design could make the UAS too costly to compete with manned
Current rules require that in controlled airspace, the UAS have voice communication with
ATC; current VHF radios also permit other aircraft in the area to hear those transmissions
this “permission” is not an FAA requirement. The C2 Link System will have to provide
performance that complies with FAA NAS requirements. This performance must include
the possible delays in the FAA networks as well as those in the C2 Link System for the
UAS. Many satellite dependent C2 Link Systems will have difficulty meeting the allocated
level of performance. Alternatives for the UA relay of ATC voice communications include
a future (2025 or beyond) capability in the FAA voice communications network, known as
the NAS Voice System (NVS), that would allow ground/ground connection between the
CS and ATC, or a purpose-built VHF ground radio installed at all locations required to
meet the airspace communications requirement.
Most manned aircraft have operating limits applied as a part of their certification process.
The UAS certification process will most likely initially limit the area of operation, the
weather conditions in which the UA can fly, and possibly even the time of day (e.g., during
daylight hours only when operations can be conducted. Reducing the possibility of
encountering other aircraft (i.e., traffic density) by timing the operation could be a risk
mitigation required by the aircraft certification process. Availability of C2 Link System
resources to support the operation must be a consideration when planning UAS missions.
Flexibility for mission planning could be a risk mitigation that could greatly reduce the
cost of a UAS if the mission allows for flexible scheduling.
Reducing the operating limitations on certified aircraft often involves data collection over
extended periods to demonstrate to the FAA that the actual risk is the same or lower than
the level of risk assumed during the certification process. Detailed records of all operations
will most likely be required for all early operational UAS.
Aircraft maintenance is key to achieving safe operations over the life cycle of any aircraft.
Traditional certificated manned aircraft are required to have a maintenance program
developed by the OEM to allow the operator to maintain the airworthiness of the aircraft.
UAS will have to comply with this requirement as well. Conventional UA designs will
most likely need to have maintenance programs similar to those for manned aircraft. Areas
of difference would include the installed equipment for DAA as well as the C2 Link System
radios. The critical nature of these unique systems will require regularly scheduled ground
checks to detect any latent failures in those systems.
The CS will also have maintenance requirements applied by the OEM to detect any latent
failures that would not be evident to the remote pilot during routine operations. The unique
aspects of the CS design will need to be examined closely to identify any conditions that
could lead to a failure of required equipment. An example could be preventing vegetation
from interfering with the proper operation of the cooling system required for computers in
the CS enclosure.
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