3. Airline operations area terminal,
4. Fixed-Base Operator (FBO) terminal, and
5. ACARS.
2.11.1 PDC Communication. It is not necessary for an aircraft to be equipped with data link communication avionics for a flight to participate in the PDC service. It is only necessary for the pilot to be able to obtain a printed or electronically displayed copy of the PDC message prior to taxi (may be printed at the FBO terminal, the airline gate, etc.).
The contents of the PDC message are relayed to the aircrew without modification, omission, or alteration. PDC is at the discretion of the clearance delivery controller. If the controller determines that issuing a PDC could introduce confusion, the controller will issue a verbal clearance to the aircrew. If the pilot is uncertain of the clearance, the PDC must not be used and the pilot must contact clearance delivery via voice (telephone or radio) and obtain their clearance.
2.11.2 PDC vs. CPDLC-DCL. The primary difference between the PDC and CPDLC-DCL services is the PDC service depends on the operator or other third party to deliver the PDC to the aircraft whereas CPDLC-DCL service is a direct connection after logon/notification from the tower automation to the flight deck avionics of FANS-equipped aircraft. See Table 2-1, PDC vs. CPCLC-DCL, below for a side-by-side comparison.
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Table 2-1. PDC vs. CPDLC-DCL
PDC CPDLC-DCL No Logon/Notification Required Logon/Notification Required Sent to AOC or other Operator prescribed location Automatically sent directly to FANS 1/A(+) equipped aircraft over data link communication equipment after crew logon/notification Delivered to the pilot by various means (i.e., over ACARS, to the FBO terminal, to the airline gate) Delivered over data link communication directly to the aircraft within 30 minutes of proposed ETD Depending on the delivery method, may require a printed copy to be delivered to the aircraft Never requires a paper copy to be delivered to the aircraft Does not require data link communication equipment to be installed in the aircraft Requires data link communication systems on the aircraft Does not support revised clearances. Revisions must be transmitted via voice frequency Revised clearances can be delivered directly to the aircraft when necessary without restrictions A specific call sign can only be used once in an adaptable time period of 12–18 hours at a specific airport Only one call sign for a given tail can be in use for CPDLC-DCL clearances at any given time Requires manual input by the pilot or may be uploaded from an AOC Clearance can be sent to the avionics system which may enable “push to load” via a load prompt
2.12 Data Authority. “KUSA” is the national data authority for all U.S. domestic CPDLC logons/notifications. Figure 2-12, Data Communication Services Strategy, describes the current and planned data communication services to be available in the domestic en route environment. CPDLC en route operations in U.S. domestic airspace will use FANS 1/A(+) equipped aircraft with multi-frequency VDL Mode 2 radios. For an alternate subnetwork, see paragraph 4.6.2.
2.12.1 Current Data Authority (CDA). When an aircraft system accepts a CPDLC connection, this active connection initiates the exchange of messages between the ATSU and the aircraft as the ATSU becomes the CDA. The CDA typically initiates address forwarding to permit a downstream or adjacent ATSU (next data authority (NDA)) to establish an inactive CPDLC connection and/or an Automatic Dependent Surveillance (ADS) contract for monitoring purposes.
2.12.2 Data Authority Transfer. When the active CPDLC connection is terminated, the aircraft will activate any inactive connection. In this case, the next data authority becomes the CDA and is now able to exchange CPDLC messages with the aircraft. Figure 2-4, Next Data Authority Notification, illustrates the transfer from the CDA to the NDA.
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Figure 2-4. Next Data Authority Notification
2.13 ATSUs and Aircraft Interoperability. Figure 2-5, Air Traffic Service Unit (ATSU) and Aircraft Interoperability Designators, shows different ATSU ground systems and interoperable aircraft systems. The diagram shows the CSP and its Centralized ADS-C System (CADS). CSP’s CADS enables an ATSU without FANS 1/A capability to receive ADS-C reports from any FANS 1/A, FANS 1/A(+) or FANS 1/A ADS-C aircraft.
A designator is assigned to each type of ATSU and aircraft data link system.
Explanations of each interoperability designator are provided below in Table 2-2.
Table 2-3, Types of Data Link Systems and Operations, provides an overview of the operational capabilities that are supported by each of the different data link systems.
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Figure 2-5. Air Traffic Service Unit (ATSU) and Aircraft Interoperability Designators Aircraft with multiple types of data link communication systems
(e.g. FANS 1/A-ATN B1 and ACARS ATS) ATSU in Oceanic ATSU in Any Airspace ATSU Continental and Remote Airspace Airspace - FANS 1/A (Generic) ACARS ATS FANS 1/A FANS 1/A+ B2* ATN B1 FANS 1/A ADS-C *As defined in this AC.
CSP Can interoperate with any B2 ground station.
CADS ATSU - CAD ACARS ATS FANS 1/A+ B2 ATN B1 2-11
Table 2-2. Interoperability Designators and Descriptions Interoperability Designator Description ACARS ATS ATS applications, DCL, OCL, TWIP, and D-ATIS supported by ACARS.
Note: The term DCL used internationally is similar to the term PDC used in the United States.
ATSU CADS CSP’s CADS enables an ATSU without FANS 1/A capability to receive ADS-C reports from any FANS 1/A, FANS 1/A(+) or FANS 1/A ADS-C aircraft.
FANS 1/A Initial FANS 1/A ATSU applications, ATSU Facilities Notifications (AFN), CPDLC, and ADS-C supported by FANS 1/A.
Note: FANS 1/A typically involves communication (CPDLC), navigation (Area Navigation (RNAV)/Required Navigation Performance (RNP)) and surveillance (ADS-C). This document refers to the FANS 1/A for the data link system, which includes the CPDLC and ADS-C applications. Refer to ICAO Doc 9613 for guidance material on navigation (RNAV/RNP) qualification and use.
FANS 1/A ADS-C ATSU applications AFN and ADS-C supported by FANS 1/A.
FANS 1/A ADS-C comply with AFN and ADS-C applications, but do not include CPDLC application.
FANS 1/A+ Same as FANS 1/A, except with additional features, such as the message latency timer function, described in DO-258A/ED-100A.
Note 1: FANS 1/A(+) aircraft is interoperable with FANS 1/A and FANS 1/A(+) ground stations. However, message latency capability is only available when FANS 1/A(+) ground stations interoperates with FANS 1/A(+) aircraft.
Note 2: Seamless transition of ATSU data link service occurs between ATN B1 and FANS 1/A(+) ground stations when:
• Aircraft equipped with ATN B1 and FANS 1/A(+) data link system also incorporates interoperability requirement IR-207, IR-209, IR-210, IR-211, IR-212, IR-214, and IR-215 of DO-305A/ED-154A.
• ATN B1 ground station incorporates interoperability requirement IRec-1 and IR-213 of DO-305A/ED-154A.
• FANS 1/A(+) ground station incorporates interoperability requirement IR-208 of DO-305A/ED-154A.
Otherwise, the pilot will lose their data link service requiring the pilot to manually perform a logon/notification to reestablish ATSU data link service.
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Interoperability Designator Description Note 3: Seamless transition of ATSU data link service occurs between B2 and FANS 1/A(+) ground stations when:
• Aircraft equipped with B2 and FANS 1/A(+) data link system also incorporates interoperability requirement NIR-153, NIR-155, NIR-156, NIR-157, NIR-158, NIR-160, and NIR-161 of DO-352A/ED-229A.
• B2 ground station incorporates interoperability requirement NIRec-3 and NIR-159 of DO-352A/ED-230A.
• FANS 1/A(+) ground station incorporates interoperability requirement NIR-154 of DO-352A/ED-229A.
Otherwise, the pilot will lose their data link service requiring the pilot to manually perform a logon/notification to reestablish ATSU data link service.
Note 4: To allow a FANS 1/A(+) data communication system on an aircraft to communicate with an ATN B1 data communication system at an ATSU, the ATSU ground system needs to accommodate the FANS 1/A(+) aircraft by incorporating the interoperability requirements of DO-305A/ED-154A.
Note 5: To allow a FANS 1/A(+) data communication system on an aircraft to communicate with a B2 data communication system at an ATSU, the ATSU ground system needs to accommodate the FANS 1/A(+) aircraft by incorporating the interoperability requirements of DO-352A/ED-230A.
ATN B1 ATS applications CM and CPDLC supported by ATN B1:
a) CM is a data link application providing DLIC.
b) CPDLC (Version 1) for ACM, ACL, and AMC.
Note 1: Interoperability for DCL, downstream clearance (DSC), D-ATIS, and flight plan consistency data link services, which are defined in DO-280B/ED-110B are not supported.
Note 2: Seamless transition of ATS data link service between ATN B1 and FANS 1/A+ ground stations when:
• Aircraft equipped with ATN B1 and FANS 1/A+ data link system also incorporates interoperability requirement IR-207, IR-209, IR-210, IR-211, IR-212, IR-214, and IR-215 of DO-305A/ED-154A.
• ATN B1 ground station incorporates interoperability requirement IRec-1 and IR-213 of DO-305A/ED-154A.
• FANS 1/A+ ground station incorporates interoperability requirement IR-208 of DO-305A/ED-154A.
Otherwise, the pilot will lose their service requiring the pilot to manually perform a logon/notification to reestablish ATS data link service.
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Interoperability Designator Description Note 3: To allow a FANS 1/A+ data communication system on an aircraft to communicate with an ATN B1 data communication system at an ATSU, the ATSU ground system needs to accommodate the FANS 1/A+ aircraft by incorporating the interoperability requirements of DO-305A/ED-154A.
Note 4: To allow an ATN B1 data communication system on an aircraft to communicate with a B2 data communication system at an ATSU, the ATSU ground system needs to accommodate the ATN B1 aircraft by incorporating the interoperability requirements of DO-353A/ED-231A.
Note 5: To allow a B2 data communication system on an aircraft to communicate with an ATN B1 data communication system at an ATSU, the B2 data communication system on the aircraft needs to accommodate the ATN B1 ground system by incorporating the interoperability requirements of DO-353A/ED-231A.
B2 Version of the Baseline 2 Data Communication system described in this section. The United States plans to use B2, as defined in AC 20-140C, as part of FAA’s NextGen initiative. An aircraft equipped with B2 is fully interoperable with any B2 ground station.
Aircraft equipped with a version of B2 other than that defined by AC 20-140C are not eligible for the B2 interop designator. B2 is comprised of the following data link applications and data link services.
a) CM is a data link application supporting the following data link service: DLIC.
b) CPDLC (Version 3) is a data link application supporting the following data link services: ACM, Clearance Request and Delivery (CRD), AMC, DCL, Data Link Taxi (D-TAXI), Oceanic Clearance Delivery (OCD), 4DTRAD, IER, In-Trail Procedures (ITP), IM, and DRNP.
c) ADS-C (Version 2) is a data link application supporting the following data link services: 4DTRAD, IER, Position Reporting (PR), IM, and DRNP.
Note 1: To allow a FANS 1/A+ data communication system on an aircraft to communicate with a B2 data communication system at an ATSU, the ATSU ground system needs to accommodate the FANS 1/A+ aircraft by incorporating the interoperability requirements of DO-352A/ED-230A.
Note 2: To allow an ATN B1 data communication system on an aircraft to communicate with a B2 data communication system at an ATSU, the ATSU ground system needs to accommodate the ATN B1 aircraft by incorporating the interoperability requirements of DO-353A/ED-231A.
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Interoperability Designator Description Note 3: To allow a B2 data communication system on an aircraft to communicate with an ATN B1 data communication system at an ATSU, the B2 data communication system on the aircraft needs to accommodate the ATN B1 ground system by incorporating the interoperability requirements of DO-353A/ED-231A.
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Table 2-3. Types of Data Link Systems and Operations Aircraft Equipment and Capability
ACARS ATS (ATSU Ground Data Link System) CADS or AOC (ATSU Ground Data Link System) FANS 1/A (ATSU Ground Data Link System) ATN B1 (ATSU Ground Data Link System) FANS 1/A– ATN B1 (ATSU Ground Data Link System)
ACARS ATS ATC communication
• DCL or PDC
• OCL Flight information
• D-ATIS
N/A N/A N/A N/A FANS 1/A ADS-C N/A Surveillance
• ADS-C (CADS) Surveillance
• ADS-C
N/A N/A FANS 1/A N/A Surveillance
• ADS-C (CADS) ATC communication
• CPDLC Surveillance
• ADS-C
N/A ATC communication
• CPDLC for
ACM, ACL, and AMC data link services FANS 1/A+ N/A Surveillance
• ADS-C (CADS) ATC communication
• CPDLC Surveillance
• ADS-C
N/A ATC communication
• CPDLC for
ACM, ACL, and AMC data link services ATN B1 N/A N/A N/A ATC communication
• CPDLC for
ACM, ACL, and AMC data link services ATC communication
• CPDLC for
ACM, ACL, and AMC data link services FANS 1/A– ATN B1 N/A Surveillance
• ADS-C (CADS) ATC communication
• CPDLC Surveillance
• ADS-C ATC communication
• CPDLC for
ACM, ACL, and AMC data link services ATC communication
• CPDLC for
ACM, ACL, and AMC data link services Note: B2 will be included at a later date.
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2.14 Performance-Based Communication and Surveillance (PBCS) Concept. The PBCS concept provides objective operational criteria to evaluate different and emerging communication and surveillance technologies and is intended for evolving Air Traffic System Management (ATM) operations. Once these criteria have been set and accepted, a specific implementation of an ATM operation including its technical and human performance may have its viability assessed against these operational criteria.
ATS system changes based on communication and/or surveillance performance align with the PCBS concept (refer to ICAO Doc 9869).
2.14.1 Aligned with Performance-Based Navigation (PBN). The PBCS concept is aligned with the concept of PBN. While the PBN concept applies RNP and RNAV specifications to the navigation element, the PBCS concept applies required communication performance (RCP) and required surveillance performance (RSP) specifications to communication and surveillance elements, respectively. Each RCP/RSP specification includes allocated criteria among the components of the communication and surveillance systems involved.
2.14.2 Communication, Navigation, and Surveillance (CNS)/ATM Model. Where beneficial, RCP, RNP/RNAV, and RSP specifications are applied to communication, navigation, and surveillance elements to ensure the operational system and its components perform in accordance with the specifications. Figure 2-6, Performance-Based CNS/ATM Model, provides an overview of the performance-based CNS/ATM model, which characterizes the relationship of the performance-based specifications among CNS elements supporting an ATM operation.
Note: Similar to the PBN concept, security is beyond the scope of the PBCS concept. However, in some cases, the RCP and RSP specifications may include criteria to support mitigations from security threats.
Figure 2-6. Performance-Based CNS/ATM Model
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2.14.3 PBCS and PBN Differences. There are some differences between the PBCS concept and PBN concept:
1. The PBCS concept applies RCP and RSP specifications, which allocate criteria to ATS provision, including communication services, aircraft capability, and the aircraft operator. The PBN concept applies RNP/RNAV specifications which allocate criteria only to the aircraft capability and the aircraft operator; and
2. The PBCS concept includes post-implementation monitoring programs, on a local and regional basis, with global exchange of information. The PBN concept includes real-time monitoring and alerting functionality in the aircraft capability.
Note: PBCS includes real-time alerts (e.g., when a communication transaction expires or a position report is overdue) that are conceptually different than the PBN alerts (e.g., RNP UNABLE).
2.15 RCP and RSP Specifications Supporting ATM Operations. To perform ATM operations within a performance-based airspace, the standards specify functional, safety and performance criteria for the applicable CNS elements. RCP and RSP specifications, in conjunction with RNP/RNAV specifications, provide these criteria and are intended to facilitate the development of standards for ATM operations. This approach is essential to the evolution of operational concepts that use emerging technologies. For example, within the organized track system (OTS) in North Atlantic High Level Airspace (NAT HLA), the Reduced Lateral Separation Minima (RLatSM) include the following requirements:
• RNP 4;
• CPDLC with RCP 240; and
• ADS-C with RSP 180.
2.15.1 RCP Specifications. An RCP specification represents operational parameters for the complete communication transaction. It is identified by a designator (e.g., RCP 240 or RCP 400) in order to simplify the designator naming convention and to make the RCP Expiration Time (ET) readily apparent to airspace planners, aircraft manufacturers, and operators. The designator represents the value for the communication ET after which the initiator is required to revert to an alternative procedure. The RCP specifications are applied to achieve the performance required of the communication process and may support aircraft separation minima.
2.15.2 RCP Parameters. The following describes the RCP parameters:
1. RCP Transaction Time. An RCP parameter that specifies the maximum time for the completion of a proportion of operational communication transactions after which the initiator should revert to an alternative procedure. Two values are specified:
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• RCP Transaction Time (TT). The maximum nominal time within which 95 percent of operational communication transactions is required to be completed; and
• RCP (ET). The maximum time for the completion of the operational communication transaction, after which the initiator is required to revert to an alternative procedure.
2. RCP Continuity (RCP C). The minimum proportion of operational communication transactions to be completed within the specified RCP transaction time, given the service was available at the start of the transaction.
3. RCP Availability (RCP A). The required probability that an operational communication transaction can be initiated.
4. RCP Integrity (RCP I). The required probability that an operational communication transaction is completed with no undetected errors.
Note: While RCP I is defined in terms of the “goodness” of the communications capability, it is specified in terms of likelihood of occurrence of malfunction on a per flight hour basis (e.g., 10-5), consistent with RNAV/RNP specifications.
Figure 2-7. Actual Communications Performance (ACP)
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