airspace. RSP is operationally derived and not based on any specific techniques, aircraft technologies, or architecture.
2.16.3 RSP Specification. An RSP specification is identified by a designator (e.g., RSP 180) in order to simplify the designator naming convention and to make the RSP Data Operational Overdue Time (OT) readily apparent to airspace planners, aircraft manufacturers and operators. The designator represents the value for the surveillance data delivery time when the surveillance data delivery is considered overdue.
RSP specifications are applied to airspace based on specific objectives (e.g., the performance required of the surveillance process used to support particular separation minima). The RSP specification is a set of requirements/operational parameters for ATS provision and associated ground equipment, aircraft capability, and operations needed to support performance-based surveillance. Surveillance performance requirements are included and allocated to system components (Required Surveillance Technical Performance (RSTP)). It includes surveillance data delivery time, continuity, availability, integrity, and safety. A specified RSP specification is intended to define the surveillance performance required of a surveillance process to support a particular ATM function.
RSP specification is applied to the airspace, route, or procedure based on the most stringent RSP specification of the required ATM functions.
2.16.4 RSP Parameters. RSP include the accuracy of the reported position, the latency in reporting the position to the controller, and the integrity, availability, and continuity of the surveillance data. The following describes the RSP parameters:
1. RSP Surveillance Data Transit Time. The maximum time for the reception of the surveillance data after which the controller should revert to an alternative procedure.
2. RSP Continuity. The minimum proportion of surveillance data delivery to be completed within the specified RSP surveillance data delivery time, given the service was available at the start of the delivery.
3. RSP Availability. The required probability that surveillance data can be provided.
4. RSP Integrity. The required probability that surveillance data delivery is completed with no undetected errors.
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Figure 2-10. RSP 180 Illustration
2.16.5 RSP 180 Illustration. In Figure 2-10, RSP 180 Illustration, the ATSU establishes an event contract with the aircraft with specific allocations described below:
1. From 1 to 2 (Aircraft). The aircraft reaches the particular event and is required to respond within 5 seconds or less 99.9 percent of the operational time (OT) and less than or equal to 3 seconds 95 percent of the nominal delivery time (DT).
2. From 2 to 3 (CSP). The signal is then transmitted through the communication service provider (CSP) network. This action must occur within 170 seconds or less for 99.9 percent of the OT and less than or equal to 84 seconds 95 percent of the DT.
3. From 3 to 4 (ATSU). From the (CSP) this message is sent through the ATSU which has a required performance of less than or equal to 5 seconds for
99.9 percent of the time and less than or equal to 3 seconds for 95 percent of the time. The total communication from the event to the controller must be less than or equal to 180 seconds with 99.9 percent probability (OT) and less than or equal to 90 seconds with 95 percent probability (DT).
2.16.6 RSP 180 Specification Tables. Table 2-10, RSP 180 Surveillance Data Delivery and Continuity Allocations—ADS-C, shows allocations for Required Surveillance Monitoring Performance/Required Surveillance Technical Performance (RSMP/RSTP) consisting of the aircraft system, network and ATSU. Table 2-11, RSP 180 Availability Criteria (Aircraft System), provides the availability criteria for the aircraft system.
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Table 2-12, RSP 180 Integrity Criteria (Aircraft System) provides the integrity criteria for the aircraft system.
Table 2-10. RSP 180 Surveillance Data Delivery and Continuity Allocations—ADS-C RSMP/RSTP Aircraft system Network ATSU
99.9% (OT) 5 170 5 95% (DT) 3 84 3 Table 2-11. RSP 180 Availability Criteria (Aircraft System) Availability Parameter Efficiency Safety Compliance Means Availability – aircraft (AAIR) N/A 0.999 Analysis, architecture, design, pre-implementation demonstration Table 2-12. RSP 180 Integrity Criteria (Aircraft System) Integrity parameter Integrity value Compliance means Integrity (I) Malfunction = 10-5 per flight hour Analysis, safety requirements, development assurance level
(e.g. Level C software) commensurate with integrity level, pre-implementation demonstration.
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Figure 2-11. RSP 400 Performance
2.16.7 RSP 400 Illustration. In Figure 2-11, RSP 400 Performance, the ATSU establishes an event contract with the aircraft with specific allocations described below.
1. From 1 to 2 (Aircraft). The aircraft reaches the particular event and is required to respond within 30 seconds or less 99.9 percent of the OT and less than or equal to 15 seconds 95 percent of the DT.
2. From 2 to 3 (CSP). The signal is then transmitted through the CSP network.
This action must occur within 340 seconds or less for 99.9 percent of the OT and less than or equal to 270 seconds 95 percent of the DT.
3. From 3 to 4 (ATSU). From the CSP this message is sent through the ATSU which has a required performance of less than or equal to 30 seconds for
99.9 percent of the time and less than or equal to 15 seconds for 95 percent of the time. The total communication from the event to the controller must be less than or equal to 400 seconds with 99.9 percent probability (OT) and less than or equal to 300 seconds with 95 percent probability (DT).
2.16.8 RSP 400 Specification Tables. Table 2-13, RSP 400 Surveillance Data Delivery and Continuity Allocations—ADS-C, shows allocations for Required Surveillance Monitoring Performance/Required Surveillance Technical Performance (RSMP/RSTP) consisting of the aircraft system, network and ATSU. Table 2-14, RSP 400 Availability Criteria (Aircraft System), provides the availability criteria for the aircraft system.
Table 2-15, RSP 400 Integrity Criteria (Aircraft System), provides the integrity criteria for the aircraft system.
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Table 2-13. RSP 400 Surveillance Data Delivery and Continuity Allocations—ADS-C RSMP/RSTP Aircraft system Network ATSU
99.9% (OT) 30 340 30 95% (DT) 15 270 15 Table 2-14. RSP 400 Availability Criteria (Aircraft System) Availability Parameter Efficiency Safety Compliance Means Availability – aircraft (AAIR) N/A 0.999 Analysis, architecture, design, pre-implementation demonstration Table 2-15. RSP 400 Integrity Criteria (Aircraft System) Integrity parameter Integrity value Compliance means Integrity (I) Malfunction = 10-5 per flight hour Analysis, safety requirements, development assurance level
(e.g. Level C software) commensurate with integrity level, pre-implementation demonstration. The aircraft end system shall be capable of detecting errors that would result in corruption, introduced by the communication service.
2.17 High Frequency Data Link (HFDL). Over the past few decades HF has provided an effective means of voice communication over long distance in oceanic and remote continental airspace. HF communication is no longer restricted to voice and provides another means of sending and receiving digital communication. HFDL augments existing VHF and satellite communications (SATCOM) (i.e., CPDLC and ADS-C) data link communication systems. A subnetwork of 15 HFDL ground stations extends worldwide communication coverage beyond that of VHF data link communication subnetworks.
2.17.1 HFDL Applications. HFDL subnetwork provides communication to both ATSU and AOC in oceanic and remote continental airspace and can be used for:
1. Non-SATCOM equipped aircraft with a long-range, cost-effective data link communication capability,
2. Data link communication in polar regions where geostationary satellite connections may not exist or be degraded, and
3. A back-up means of data link communication for SATCOM (CPDLC and ADS-C) equipped aircraft.
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2.17.2 Ionosphere HF Disturbance and Reliability. HF is subject to temporary signal distortion due to changes in the ionosphere layer shape and density. Because of multiple HFDL ground stations, ionosphere disturbances are less frequent than in the early days of HF voice. Modern aircraft HFDL systems automatically search for the best available frequency from all HFDL operational ground station frequencies. Once a suitable frequency is found, the aircraft establishes a connection by sending a logon/notification message to the ground station. A logon/notification confirmation uplink is established enabling the pilot to send data.
Note: Monitoring data have shown that HFDL does not meet RCP 240/RSP 180.
2.18 Future U.S. Domestic Airspace Data Link Communication Services. Figure 2-12 depicts future plans for data link communication services. Though this planning diagram is subject to change, it generally provides a preview of expanding data link services in the next few years. This is added to the AC to enable operators planning upgrades in pace with future technology and upcoming data link communication services.
Figure 2-12. Data Communication Services Strategy 14 18 20 22 24 26 28 30 Controller-Pilot Data Link (CPDLC) Departure Clearances (DCL) Segment 1 Phase 1
- Tower Service Deployment to 55 Towers Complete - DEC 2016 (2½ years ahead of schedule) Transfer of Communications Segment 1 Phase 2 Initial Check-In
- En Route En Route Altimeter Settings Altitudes PLANNED FOR Services Initial Speeds (Limited) ALL 20 ARTCCS Baselined Services Crossing Restrictions (Limited) May 2012 Airborne Reroutes / Go Button Controller Initiated Reroutes (Limited) Direct-to-Fix (Initial) Baselined Controller Initiated Routes (Full) October 2014 Crossing Restrictions (Full) Direct-to-Fix (Full) PLANNED FOR Baselined En Route Full Advisory Messages ALL 20 ARTCCs August 2016 Services Holding Instructions Speeds (Full) Deferred Full Stuck Microphone Adapted Arrivals Services Beacon Codes Segment 2 Dynamic RNP
- Advanced Services Formulation In Budget 4D Trajectories (4DTRAD) Advanced Interval Management Tailored Arrivals Avionics D-TAXI FANS 1/A ATN/IPS and FANS 1/A Ground System Future Air Navigation System (FANS)
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2.19 Data Communication Services Strategy. Segment 1 in Figure 2-12 consists of two phases.
2.19.1 Tower Services and En Route Services. Segment 1, Phase 2 (S1P2) services will be delivered in two stages, “initial” services and “full” services. S1P2 en route services are expected to begin in 2019 and are planned to leverage existing Phase 1 FANS 1/A aircraft and expand Phase 1 infrastructure to deliver CPDLC services in the U.S. domestic en route airspace. Listed below are en route initial and full services:
1. En Route Initial Services. The initial services in S1P2 will include the following:
• Transfer of communications,
• Initial check-in,
• Altimeter settings,
• Altitudes,
• Speed (limited),
• Crossing Restrictions (limited),
• Airborne reroutes/go button,
• Controller initiated reroutes (limited), and
• Direct-to-fix (initial).
2. En Route Full Services. With the continuation of S1P2, en route full services will include (see the following paragraphs for descriptions of some initial and full service features):
• Controller initiated routes,
• Crossing restrictions,
• Direct-to-fix,
• Advisory messages, and
• Holding instructions.
Note: The full services of speed, stuck microphone, adapted arrivals, and beacon codes are deferred until further notice.
2.19.2 Speeds.
1. Initial Services. The controller can issue UM61 CROSS (position) AT AND MAINTAIN (altitude) AT (speed).
2. Full Services (Deferred). The controller will be able to:
• Issue speed clearance providing the pilot with instructions to maintain a speed in Mach number or indicated airspeed, 2-30
• Assign speeds of greater than or less than specific values, and
• Instruct the pilot to resume normal speed or to maintain present speed. The pilot will be able to request a speed clearance.
2.19.3 Crossing Restrictions. Initially, the controller will be able to use two crossing restriction message elements to instruct the pilot to cross a specific fix at a specific altitude and, if desired, at a specific speed. With full service, the controller will have considerably more flexibility in composing crossing restriction clearances. For example, the controller will be able to clear an aircraft to cross a specific fix at a specific time and have the option of entering a crossing restriction.
2.19.4 Routes. Initially, the pilot will be able to DM22 REQUEST DIRECT TO (position).
The controller will be able to issue route clearances, such as UM74 PROCEED DIRECT TO (position), UM79 CLEARED TO (position) VIA (route clearance), UM80 CLEARED (route clearance), and UM83 AT (position) CLEARED (route clearance). With full service, the controller’s workstation will be enhanced to support entry from the Radar (R) and Radar Associate (RA) positions and permit entry of route offsets with additional message elements.
2.19.5 Advisory. Air Traffic personnel issue advisory messages to aircraft on a routine basis.
Examples include dynamic airport information (runway closures, runway visual range, braking action, etc.), convective significant meteorological information (SIGMET), Central Weather Advisories (CWA), Pilot Weather Reports (PIREP), weather displayed on the controller’s scope, and current ride reports. CPDLC will allow the controller to send a limited set of advisory messages to the aircraft on a case-by-case basis or to all aircraft with which the controller has a CPDLC connection. Advisory messages such as SIGMETs and CWAs, which must be broadcast to all aircraft on frequency, will still need to be verbally broadcast in a mixed equipage environment. However, advisory messages that are issued to individual aircraft, such as dynamic airport information, displayed weather, PIREPS, and current ride reports are excellent candidates for automating. S1P2 CPDLC services will only support ride reports and free text messages created at the sector. The messages will be provided to the controller to send to the appropriate aircraft. In addition to freeing the controller from verbally delivering the advisory, CPDLC also allows positive confirmation that affected aircraft have received the information.
2.19.6 Holding Instructions. The controller may be directed to hold all arrivals for a particular airport. With full service, the controller will be able to send a CPDLC message UM91 HOLD AT (position) MAINTAIN (altitude) INBOUND TRACK (degrees) (direction) TURN LEG TIME (leg type).
2.19.7 Stuck Microphone (Deferred). With full service, the controller will be able to instruct the pilot to check their microphones.
2.19.8 Adapted Arrivals (Deferred).With full service, the controller and pilot will be able to use CPDLC to execute adapted arrival procedure. The adapted procedure contains both lateral and vertical aircraft maneuvers and provides greater efficiency for users.
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2.19.9 Beacon Codes (Deferred). As aircraft transition in U.S. domestic airspace from one facility to another, there is the possibility of beacon code duplication. Often this happens when there is significant traffic and/or delays in the system. It is also prevalent at facilities which border foreign airspace. Today, when this conflict occurs, En Route Automation Modernization (ERAM) will assign the aircraft a new code and notify the controller, who then verbally issues it to the pilot. With CPDLC, the FAA ground system will automatically send a UM with the new code to the aircraft at the appropriate time with no controller involvement. The controller will also be able to manually compose and send a beacon code message if needed.
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CHAPTER 3. AIRCRAFT ELIGIBILITY
3.1 Introduction. This chapter provides guidance on how operators can determine if their aircraft data link system is compliant and eligible for operational use. This AC does not address design approval or installation of data link systems. For airworthiness guidance, refer to AC 20-140( ), Guidelines for Design Approval of Aircraft Data Link Communication Systems Supporting Air Traffic Services (ATS).
3.2 Aircraft Eligibility. The Airplane Flight Manual (AFM) should identify the following for data link communication eligibility:
1. Interoperability,
2. Subnetwork, and
3. Aircraft performance.
Note: Descriptions of the data link services are provided for a given airspace or operation. For example, in the United States, departure clearance (Controller-Pilot Data Link Communication–Departure Clearance (CPDLC-DCL)) service requires the aircraft to be interoperable with Future Air Navigation Systems (FANS)-1/A(+), to use either the Very High Frequency (VHF) Data Link (VDL) Mode 0/A or VDL Mode 2 subnetwork, and to not have any prescribed aircraft performance requirements. Operators should refer to the requirements defined by the Air Traffic Service Unit (ATSU) for each operation.
A summary of typical operational requirements is provided in Chapter 5, Operational Use of Data Link Communications, of this AC.
3.3 Statement of Compliance (SOC). Due to the complexity of the criteria to determine eligibility, the operator must obtain a statement of compliance from the entity that owns the design approval for their data link installation. This may be the aircraft manufacturer, the operator, the manufacturer of the data link system, or another party. The statement of compliance should be provided in the AFM, AFM Supplement, or other acceptable document. Table C-3, Preferred Original Equipment Manufacturer Annotation, provides an example of a statement of compliance. The statement of compliance must indicate the aircraft data link system meets the aircraft-allocated requirements of Required Communication Performance (RCP) and Required Surveillance Performance (RSP) specifications.
Note: For a FANS 1/A CPDLC and Automatic Dependent Surveillance-Contract (ADS-C) aircraft system, RTCA DO-306/European Organization for Civil Aviation Equipment (EUROCAE) ED-122, Safety and Performance Standard for Air Traffic Data Link Services in Oceanic and Remote Airspace (Oceanic SPR Standard), is equivalent to RCP 240, RCP 400, RSP 180, and RSP 400 specifications. For an Aeronautical Telecommunications Network (ATN) Baseline 1 (B1) or FANS 1/A CPDLC aircraft system, RTCA DO-290/ED-120, Safety and Performance Requirements Standard for Air Traffic Data Link 3-1
Services in Continental Airspace (Continental SPR Standard), provides performance criteria for the EUR Region.
3.3.1 Alternate Means of Compliance for No SOC. In lieu of the SOC stated in the AFM, AFM Supplement, or other acceptable documentation, operators may provide a detailed submission to the FAA validating that the aircraft’s current system meets the RCP/RSP applicable requirements. As a minimum, this submission should include information on avionics continuity, integrity, availability, and safety and monitoring/alerting requirements (refer to RTCA DO-306/ED-122). Equipment manufacturer support should be solicited to acquire suitable documentation.
3.3.2 Interoperability. The operator must confirm the interoperability of their aircraft data link system (interoperability requirements standards (INTEROP) designators are described in Table 2-2, Interoperability Designators and Descriptions). The statement of compliance must indicate the INTEROP and a reference to the definition of that INTEROP. Aircraft Communications Addressing and Reporting System (ACARS) ATS, FANS 1/A, FANS 1/A+, and ATNB1 INTEROP designators, and/or the compliance statement, must reference AC 20-140 or later revision. For the ATN Baseline 2 (B2) INTEROP designator, the compliance statement must reference AC 20-140C or later revision.
3.3.2.1 In U.S. domestic en route airspace, for operations supported by FANS 1/A(+) data link communication systems, the avionics system must have “push to load” capability into the navigation system whenever a routing change (e.g., uplink message (UM)79, UM80, and UM83) is received.
Note: Operators using an alternate means of compliance for “push to load” will not be permitted once full services are implemented.
“Full services” require fully integrated (“push to load”) avionics. For a description of “Full Services,” see Figure 2-12, Data Communication Services Strategy.
3.3.3 Subnetwork. The operator must confirm the subnetwork capability of their aircraft (subnetworks are described in paragraph 2.2.2). The statement of compliance must indicate the subnetworks that are supported and a reference to the definition of the subnetworks. The compliance statement must reference AC 20-140 or later for any of the following subnetworks:
• VDL M0/A,
• VDL M2,
• High Frequency Data Link (HFDL),
• Inmarsat, and
• Satellite communications (SATCOM) Iridium (Short Burst Data (SBD)).
Note: For aircraft utilizing Inmarsat (SwiftBroadband (SBB)), the SOC must reference AC 20-140C or later.
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3.3.4 VDL M2 Requirements for U.S. Domestic En Route. The VDL M2 requirements include aircraft that are equipped with VDL Mode 2 equipment approved to Technical Standard Order (TSO)-C160a, Very High Frequency (VHF) Digital Link (VDL) Mode 2 Communications Equipment, (see Note 1 below for details) or later that is capable of tuning to more than one VDL M2 channel.
Note 1: Minimum performance standard of TSO-C160 does not include the capability for the Communications Management Unit (CMU) (Avionics Architecture Class W and Z) or VDL M2 Radio (Avionics Architecture Class X) to tune to more than one VDL M2 channel. The above equipment is capable of tuning to only one VDL M2 channel (i.e., 136.975 MHz). The minimum performance standard of TSO-C160 for VDL M2 Radio (Avionics Architecture Class V or Y) contains the capability to support VDL Mode 2 multi-frequency operation when integrated with a CMU (Avionics Architecture Class W and Z) that supports VDL M2 multi-frequency according to TSO-C160a.
Note 2: The FAA accepts the use of VDL M0/A en route when VDL M2 communications are lost, if the aircraft is equipped with a properly functioning VDL M2 radio before starting the flight or dispatching. An alternate subnetwork may be used provided it complies with paragraph 4.6.2. Table C-1, Summary of Airspace Requirements, provides a summary of airspace requirements.
3.3.5 Performance Data for Compliance. The operator should evaluate the demonstrated performance of their aircraft data link system as provided by the FAA and other Air Navigation Services Providers (ANSP) as part of the ANSP monitoring programs.
FAA monitoring data is available for initial and continuous compliance and operator data may be acceptable for initial data link eligibility. Actual Communications Performance (ACP) of the CPDLC two-way communications and Actual Surveillance Performance (ASP) of the ADS-C are evaluated against respective RCP and RSP specification standards. This data should be included to quantify support of the aircraft performance portion of the data link eligibility. If no performance data is available, then initial compliance for applicable airspace will be based on the SOC with performance being monitored as data is collected. (See Chapter 6, Performance Monitoring.)
Note 1: For fleet aircraft, records for every tail number are not necessary provided that all the aircraft have the same data link communication configuration. Operators with a single aircraft may meet the above requirement using records of other aircraft with the same make, model, and series (M/M/S) and the same data link communication configuration.
Note 2: RCP and RSP performance data is not required for aircraft operating only in U.S. domestic airspace.
3.4 Configuration Control. Operators should maintain their aircraft in an avionics configuration which has been shown to provide acceptable data link communication performance. A list of recommended avionics is available at http://dcis.harris.com/newoperator-documents.
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