Gerry Corbett 28 January 2013 · 2013-09-16 · Presentation to ICAO ACP Gerry Corbett 28 January...
Transcript of Gerry Corbett 28 January 2013 · 2013-09-16 · Presentation to ICAO ACP Gerry Corbett 28 January...
UASSG – RPAS Command and Control Links
Presentation to ICAO ACP
Gerry Corbett
28 January 2013
Scope…………………
• Introduction/outline of C2 link tasks
• Elements from GM chapters affecting ACP
• Additional points/issues
C2 link supports the following communication tasks• Control uplink to RPA:
– data to modify behaviour and state of the RPA;• Control downlink from RPA:
– data to indicate the position and status of the RPA;• Detect and avoid downlink:
– sensor data and processed sensor information (related to, traffic, weather, terrain airport visual data,) and manoeuvre recommendations (RA) and detect and avoid automatic response (initiation and description), etc. ;
• Detect and avoid uplink:– sensor selection /control, CA auto response state select (on/off) and override (pilot option to cancel CA manoeuvre) ;
• Data to support RPS handover – data from transferring remote pilot/RPS to accepting remote pilot/RPS
• Data to support RPS handover – data from accepting remote pilot/RPS to transferring remote pilot/RPS.
• Data to support ‘Flight Data recording ‘ requirements • The link will also provide acknowledgment to the remote pilot or the RPS of correct receipt of critical data
ATC voice and data link communication tasks may be relayed between the aircraft and the RPS on the same C2 link..
• ATC voice communication relay (ATC to remote pilot via RPA) VHF,• ATC voice communication relay (remote pilot to ATC via RPA) VHF;
– Note: It is unlikely that ATC HF and /or satellite voice will be relayed though the RPA as there are more efficient direct alternatives;
• ATC data link relay (ATC to/from RPA) (eg Link 2000,local air space requirement) .
Typical operational configurations
• VLOS only operation• BVLOS Control
– pilot does not visually monitor the aircraft and may be based at the operating airfield or many thousands of miles away
– control interface may be restricted when compared to that of a conventional manned aircraft
– the delay resulting from the C2 link may be significant in certain situations. • difference between Radio line of sight operation and Beyond radio line of
sight – From an operational perspective, key difference will be the delays associated
with control and display information and – the design features selected to accommodate for the available link capacity. – Given that BRLOS C2 links in general are expected to have lower data capacity
and suffer higher message delays than RLOS C2 links
Classes of BVLOS RPS Control• 3 broad classes with different minimum control interface capabilities
– for which different Pilot licences type rating may be required. • BVLOS Class A Attitude control RPS (Basic Instrument flying)
– sufficiently low communication delays to allow conventional aircraft attitude displays to work correctly and for pilot inputs equivalent to a control stick and throttle to be available.
• BVLOS Class B Vector control RPS ( Conventional autopilot)– moderate delays in the C2 link such that heading altitude ( level) and speed can be accurately
monitored and the provision of a pilot interface that allows these parameters to be directly controlled.
• BVLOS Class C Strategic Control RPS ( waypoint steering)– Characterised by significant delay in the C2 Link such that key flight parameters cannot be
accurately monitor in real time and that pilot control is limit to changing 4d waypoints in the pre‐planned mission.
Plus• Combinations of the above
• VLOS control (or monitoring with the potential to take control if necessary) for takeoff and or landing with handover to BVLOS control once airborne
BRLOS and RLOS terminology• C2 architectures usually classified as
– Radio Line of Sight (RLOS ) or– Beyond Radio Line of Sight. BRLOS
• While these terms are well established they imply different things in different situations• RLOS ‐ can mean
a) Direct radio line of sight from the RPS to the RPAb) situations where the RPS is linked to a remote transmitter via an extensive ground network’ providing that the remote
transmitter has direct radio line of sight to the RPA • BRLOS
– generally accepted meaning‐ use of a satellite communication link directly connected to the RPA – The label BRLOS provides no information about
• the network between the RPS and the satellite nor• the number of earth to satellite signal hops nor• the consequential signal delay.
• BRLOS is assumed to introduce the key operational challenges of– increased and potentially unpredictable signal transmission delay– regulatory challenge of certification or regulatory oversight of the Satellite Communication Service Provider
• However the key challenges of BRLOS may typically be present in the second case of RLOS ( Case b) above) these include
– increased signal delay and involvement of a external communication service provider
• If fact there is no significant regulatory difference between case b) RLOS and BRLOS, as generally understood, Also• There is no agreed term for situations where a satellite link is used as part of the ‘ground network’ described in
case b) if the final link to the RPA is from a ground relay station remote from the RPS• Nor is the case where the satellite network used to link to the RPA is wholly under control of the RPA operator (
e.g. a private dedicated satellite adequately covered in the naming conventions.
C2 Architectures
a) RLOS C2
• Co‐located RPS and transmitter
• Single remote transmitter – Linked to RPS via private network (RPAS operator controlled )– Linked to RPS via a Communication service provider network
• Multiple remote transmitters– Linked to RPS via private network(RPAS operator controlled – Linked to RPS via a Communication service provider network
BRLOS C2
• Satellite
• Co‐located RPS and satellite transmitter
• private (RPAS Operator Controlled ) satellite network
• Single satellite
• Multiple satellite
• Communication service provider satellite network
• Single satellite
• Multiple satellite
• Remote satellite transmitter
• private (RPAS Operator Controlled) satellite network
– Single satellite
– Multiple satellite
• Communication service provider satellite network
– Single satellite
– Multiple satellite
Dual simultaneous differential link architecture
Using• both RLOS and BRLOS or, • either dual RLOS or • dual BRLOS with different frequency,to increase link availability/quality of service.
Note 1 RPS may be located on the ground or on a moving platform (e.g. ship, aircraft etc).
Note 2 While in principle all of the above options could be used to support VLOS operations it is likely that most VLOS activities will use option a (1) the RLOS collocated RPS and transmitter, typically in a hand held configuration
Note 3 Aircraft relay of ATC Voice to/from RPA using the C2 Link
Whichever architecture is selected, if the C2 link is used to relay ATC voice via the RPA, the architecture design needs to accommodate this (see section 10.6)
C2 –Required Communication Performance (C2-RCP)
• The C2 RCP concept is derived from ICAO Doc 9869
– used to assure confidence that the operational communications supporting the RPASfunctions will be conducted in an acceptably safe manner.
• The specific C2 RCP requirements will depend on
– the operation being carried out and
– the requirements of the given airspace.
– The required C2 RCP type(value) results from the analysis of specific operations to be undertaken, system design and equipage.
• ATC communication will also have a required ATS RCP
– a special assessment of Voice communication requirements may be required to allow the allocation of an RCP Type
– If the ATC (voice or data) communication is relayed via the C2 link, the link must support the requirements of the most demanding RCP.
– If ATC voice communication is relayed though a ground data link that link must also meet the required RCP.
• The C2 RCP Type parameters need to be agreed but will include:– Communication transaction time
– Continuity
– Availability
– Integrity
Implications of Link Quality of service
• RPAS systems design should be such that either– a loss of the C2 link does not directly lead to a catastrophic event (although
normal operation will be suspended and a lost link procedure initiated.) or‐ the probability of link loss due to all possible causes should be lower than the
acceptable probability of a catastrophic event.
• Given the above, there will be a trade‐off between Link RCP ( and the pilots ability to command a manoeuvre) and the integrity of the auto collision avoidance function
• If link availability is very high, then the overall safety is less dependent on the operation of the Auto CA system, however if the link is less reliable both the pilot initiated separation function and the Pilot initiated collision avoidance functions may be lost and the integrity required of the auto CA system is much higher. This could lead to the need for a duplex or even triplex redundant CA function.
Requirements for Certification and operational approval of datalink component and providers
• To ensure that the C2 link meets the required performance standards, regulatory oversight will be required– Where all the components of the link are under the direct control of
the manufacturer /operator then the components of the communication system will be certified as part of the system.
– Where some of the components are controlled by a ‘communication service provider’ e.g. a satellite system operator or a terrestrial communication network provider, (which is typically the case for BRLOS and may apply to RLOS operations), then the service provider will either
• need to be certified by the appropriate regulatory authority or• it may be acceptable for oversight to be applied indirectly though the RPAS
operator who has contracted the service.
• It will also be necessary to guarantee the QoS of the RPAS specific element of the ATC voice communication link including– the voice relay from RPA to RPS via satellite or– a direct land line link from ATSU to the RPS provided by a
communications service provider.
Expected requirements for Communications Service Provider (CSP) oversight
• The CSP shall ensure that the C2 and ATC Voice relay services meets the performance criteria, defined by the RPA operator in agreement with the Regulator
• it is expected that the C2 safety criticality requirements will be more demanding (e.g Hazardous) than the ATC voice (e.g Minor)
• ATC voice may use a direct ground link provided by a CSP which will also need safety oversight.
• The CSP shall be under safety oversight either by:– The RPAS operator, when contracted by them; or– directly by the competent aviation authority established by the State on a national or regional
basis.• in the event that safety oversight is undertaken by the RPAS operator, it takes
responsibility to– demonstrate to the competent authority that proper mechanisms exist to oversee the
contracted CSP, and– inevitably attracts on itself some liability also for the contracted communication service.
• A process for certification or approval of Communication Service Providers will need to be developed
– if responsibility for oversight of the Communication Service Provider is delegated to the RPASoperator an appropriate procedure will need to be agreed with the regulator
Link management procedures - Frequency/Bandwidth
• There will be a need to allocate specific frequencies as required on a daily/ hourly etc basis. – The frequency allocation for the RPA C2 link will need to accommodate
• the requirements for a specific area and • the requirements of flights which transit from one area to another.
– This may become a particular challenge in areas where large numbers of UAS operations are taking place. Without some form of ‘regional allocation’ there is a risk that more than one UAS could be authorised to operate on the same frequency at the same time in the same location.
• The use of a ‘centralised’ network C2 communication provision may be a long term solution. – This may eventually need international harmonisation.
• In high density environments, a method may be required to ensure that the only the correct RPA receives the message from the appropriate ground station.
Additional Unresolved Issues
Scope of SARPS?
• Existing SARPs cover technology independent safety requirements for the systems, – (e.g. frequency bands, protection from interferences, integrity,
availability, continuity, timeliness and security), • And also all other radio‐frequency characteristics necessary for
interoperability – (e.g. coverage, signal strengths, modulations) as well as definition of
the protocols for digital communications.• The scope of the future ICAO SARPs for C2 could cover only safety
and performance, technology independent provisions, but not interoperability provisions between different types of RPS and different types of RPA.
• Given that the compatibility between RPS and specific types of RPA will be checked during the type certification process of the RPA and recorded in the data sheet attached to the TC.
‘Party Line’ ?
• Should the current ‘party line’ effect (where all aircraft on frequency can hear voice communications between other aircraft as well as ATC) be stated as a mandatory requirement for all communications between Remote Pilot and ATC?
• This would appear to be a minimum safety requirement in airspace where voice communication is used routinely (Eg. in busy airspace or where aircraft are operating in relatively close proximity). .• Such a requirement would place additional bandwidth requirements
on the C2 link (if RPA used as the relay) or additional cost/complexity (if a direct ground link between RPA pilot and ATC is used).
Spectrum allocation • It is assumed that the spectrum used for the C2 link for RPA operations will
be within internationally agreed aeronautical protected spectrum or possibly within agreed national bands.
• In either case, the day to day allocation of spectrum for RPA operations will require a different approach to that currently adopted for ATC voice sector frequencies, as a unique channel or set of channels will be required for each RPA operating in a given area.
• Given the expected bandwidth requirements, opportunities for frequency sharing may be limited.
• Also it may not be possible for an individual RPA on a long duration mission (either local or long range) to keep the same C2 frequency for the duration of the flight because of demands from other users and cross border requirements.
• Either national or international procedures for managing this will be required.
Limitations of locally allocated spectrum
• There is a potential issue for the future with regard to C2 spectrum for Visual Line of Sight (VLOS) operations – while VLOS operations remain ‘contained’ to a small local area the frequency requirements can be dealt with at a national level.
• However, once small UAS are allowed to be used over more extended distances/heights, then they will begin to mix with other international traffic and use of protected spectrum will probably be required – there may be a need to establish the ‘break point’ at which this changeover occurs (specific range/height ?).
• This is linked to the Scope of SARPS discussion
Alternative ATC Comms architecturesThe lack of a pilot in the aircraft potentially allows other ATC Comms architectures
– pilot to ATC comms would not necessarily have to route via the RPA) –
– what forms are/are not acceptable?a) Relay via RPA
i) Using Same link as the C2 ( Baseline)
ii) Dedicated link to relay encoded voice comms independent of C2 link
b)Transmission via other network
i) Direct RPS to ATC via point to point VHF radio
ii) Relay via 3rd party network
Requirements include:
– ‐RPS /ATC Voice communication need to be re‐ broadcast on sector frequency
– ‐Communication between ATC to other aircraft in the sector must be relayed to the RPS.
Notes:
1) Crossed transmissions are more likely to occur due to differential delays between the two communication routes
2) Implies infrastructure changes within the ATC centres
iii) Simple phone link to ATCO ‐
– No ‘party line’, ATCO workload and distraction, ATC Infrastructure changes
Other points• Assuming that there will inevitably be occasions when the C2 link is interrupted or
‘drops out’, what is the view on the acceptable length of such (short duration) dropouts. In other words, how long do we give before we declare a ‘routine/inconsequential’ drop out to be a full ‘Lost Link’ situation?
– Currently suggestion 10 seconds
• If C2 link is lost, is it acceptable to utilise the comms spectrum allocated to the UAS’s payload (cameras, sensors etc) as a reversion?
• C2 Link encryption? Possibly required to avoid risk of 3rd part capture of the link, or to prevent spoofing. How would such encryption keys be controlled if used between a large number of ‘small’ independent operators?
• Adequate frequency separation between individual C2 Data Links in order to prevent interference ‐ how much ‘gap’ is required?
• Data recording parameters ‐ recording in both RPA and RPS? How much information needs to be sent from the RPA for recording in the RPS (particularly if the RPA cannot be recovered)? Has implications on the bandwidth required for each C2 Link.
• Possible use of a short range link to support the final approach and taxiing aspects at an airfield.
Identification of Amendments to Annex 10It is likely that all five volumes will need some amendment; consideration may also need to be given to
the generation of new volumes specific to the C2 link and /or the ‘signal in space’ issues which may be associated with a Detect and Avoid function –
Panel support will be necessary in the following areas of Annex 10 :• Vol 1 – Nav Aids ‐ RPA are unlikely to use conventional navigation aids, but will instead rely on GNSS
navigation solutions –– issues of integrity and availability of such aids will need to be considered..
• Vol 2 ‐ Communication procedures ‐ Given the principle of transparent insertion of RPA into the airspace, this volume should not be affected significantly, however
– some additional parameters eg ‘maximum voice communication transport delay’ may be required due to voice relay via the aircraft
– proposed use of a ‘reversionary RPA pilot to ATC voice link’ (Eg. via a direct telephone line) will need to be addressed.
– the implications of using digital data link communications from ATC to RPA have not yet been considered• Vol 3 ‐ Communications systems ‐ Assuming the C2 link is addressed in a separate volume, no
significant changes to this volume are anticipated other than– possible change to the Mode S/ ACAS logic to allow the RPA (non ACAS) collision avoidance function
to receive information from ACAS of an intruder of its intended avoidance manoeuvre. • Vol 4 ‐ Surveillance Radar and Collision Avoidance Systems ‐ Again assuming that RPA Collision
avoidance is defined in a separate volume, little change is expected to this volume), other than the introduction of a new mode S code to indicate a ‘lost C2 condition’
• Vol 5 – Spectrum ‐ This will require update to address both any additional spectrum made available for Aeronautics use by WRC and to capture the decision about the use of protected aeronautical spectrum for C2 links and or the FSS for RPA C2.