Detailed working notes on the ICAO Aeronautical Telecommunication Network using the Internet Protocol Suite (ATN/IPS). This folder expands the summary in topics/atn_ips.md into per-aspect files.

Files in this folder#

• overview.md — what ATN/IPS is, where it sits in the ICAO/ATM framework, and how it relates to FCI, SWIM, and datalink topics.
• components.md — building blocks: protocol stack layers, security components, ground/air-ground domains, end systems and routers.
• blocks.md — migration generations (ATN/OSI era, ATN/IPS transition, FCI integration) and domain types; mermaid diagram.
• threads.md — functional axes: IPv6 networking, security, ground-ground backbone, air-ground over FCI, application migration, governance/standardisation.
• modules.md — worked example: one air-ground ATN/IPS dialogue for CPDLC Baseline 2 over multilink (LDACS + Iris SATCOM).
• enablers.md — CNS infrastructure, regulatory framework, security PKI, spectrum, training, institutional arrangements.
• performance_objectives.md — KPA matrix: interoperability, safety, security, capacity, cost-effectiveness.
• timeline.md — year-keyed evolution from ATN/OSI to ATN/IPS; Doc 9896 editions; PENS/NewPENS; FCI milestones.
• references.md — consolidated ICAO and authoritative external references for everything in this folder.

Reading order#

Start with overview.md, then components.md for the protocol architecture, then blocks.md for the migration framing. Read threads.md to understand functional axes. Use modules.md for a concrete worked example. enablers.md and performance_objectives.md are reference depth. timeline.md provides historical context and references.md provides citations.

Source basis#

Content is grounded in:

• ICAO Doc 9896 (Manual on the ATN using IPS Standards and Protocols, Third Edition, 2026, advance unedited) — primary source.
• Annex 10, Volume III (Aeronautical Telecommunications — Part I, Chapter 3: ATN SARPs; Chapter 7: AeroMACS).
• Doc 9880 (ATN/OSI Technical Specifications) — legacy baseline for migration context.
• EUROCONTROL PENS/PENS2 documentation — ground-ground CSP.
• SESAR 3 JU Iris project — satellite ATN/IPS datalink.

What ATN/IPS is#

ATN/IPS is the Aeronautical Telecommunication Network using the Internet Protocol Suite. It is ICAO's IPv6-based networking architecture for aeronautical communications, standardised in Doc 9896 (Manual on the ATN using IPS Standards and Protocols, Third Edition, 2026). It defines the protocols, addressing plan, security mechanisms, and organisational model that make an interoperable global aeronautical IP network possible.

ATN/IPS is the successor to the legacy ATN/OSI architecture, which uses ISO CLNP for networking. CLNP is being replaced by IPv6; the ISO OSI transport stack is being replaced by TCP/UDP; and OSI upper-layer protocols are being replaced by TLS and DTLS. The application layer — the CPDLC and ADS-C dialogues — is preserved through an adaptation layer (the ATN Dialogue Service / ATNPKT) that maintains protocol compatibility with legacy applications.

Where ATN/IPS sits in the ICAO/ATM framework#

 ICAO SARPs layer:      Annex 10 Vol III, Chapter 3 (ATN SARPs)
                         |
 Technical layer:        Doc 9896 (ATN/IPS Manual, 3rd Ed.)
                         |
 Application layer:      CPDLC / ADS-C / ATSMHS / SWIM / AOC
                         |
 Network layer:          ATN/IPS (IPv6, TCP/UDP, DTLS/TLS)
                         |
 Datalink/subnetwork:    LDACS / AeroMACS / Iris SATCOM / VDL2
                         (Future Communications Infrastructure)

ATN/IPS occupies the network layer. It is transport-agnostic: the same IPv6 network functions regardless of whether the underlying A/G subnetwork is LDACS (L-band continental), AeroMACS (airport surface), Iris SATCOM (oceanic/remote), or VDL Mode 2 (legacy continental). The Future Communications Infrastructure (FCI) — covered in the sibling fci topic — provides the link layer.

Relationship to sibling topics#

• FCI (fci) — provides the link-layer subnetworks (LDACS, AeroMACS, SATCOM) that carry ATN/IPS IPv6 packets. ATN/IPS is the network layer; FCI is the layer below.
• Datalink / CPDLC (datalink) — CPDLC and ADS-C are the primary ATS applications carried over ATN/IPS. The datalink topic covers the CPDLC service; ATN/IPS covers the network that delivers it.
• SWIM (swim) — SWIM services run as native IP applications over the ATN/IPS ground-ground network. ATN/IPS is the ground backbone SWIM depends on.

ICAO standardisation history#

ATN/IPS has been under development since the early 2000s. The first edition of Doc 9896 standardised the basic IPS concepts. The second edition mandated Mobile IPv6 for mobility. The third edition (2026, advance unedited) replaces Mobile IPv6 with the AGMI/GB-LISP mobility architecture, targets ATN Baseline 2 services, and introduces enhanced reliability mechanisms. The Aeronautical Communications Panel (ACP) is the ICAO body responsible.

Regional implementation proceeds through PIRG agreements (Annex 10 Vol III §3.3.2). The ATN Baseline 2 standard (EUROCAE ED-228B / RTCA DO-350B) defines the operational safety requirements. RTCA DO-379/EUROCAE ED-262 profiles the IETF RFCs needed for interoperability. ARINC 858 defines the airborne IPS system requirements.

Why ATN/IPS matters#

Legacy ACARS networks (and even early ATN/OSI deployments) are either proprietary or use expensive legacy protocols. ATN/IPS enables COTS IPv6 infrastructure to carry safety-critical communications, reducing cost while maintaining the required safety and security levels. It is the networking foundation for Block 1 and Block 2 ASBU capabilities — SWIM services, FF-ICE information exchange, and the multilink air-ground connectivity that enables Trajectory-Based Operations.

References#

• Annex 10 (Aeronautical Telecommunications), Volume III, Part I, Chapter 3, §3.4.1 — normative choice between OSI and IPS for the ATN.
• Doc 9896 (Manual on the ATN using IPS Standards and Protocols), Third Edition (2026), Foreword — document purpose and relationship to Annex 10 Vol III, Chapter 3.
• Doc 9896, Part I, Chapter 1, §1.1.1 — scope of the manual: interoperability across administrative domains in the ATN/IPS internetwork.
• Doc 9896, Part IV, Chapter 1, §1.1.1 — third edition purpose: ATN/IPS for Baseline 2 ATS services.
• Doc 9896, Part IV, Chapter 2, §2.1.1 — ATN/OSI experience gained; Iris SATCOM commenced ATN/OSI operations in support of Baseline 2 in 2025; basis for ATN/IPS migration design.

ATN/IPS is not a single device or service. It is a structured set of protocol layers, node types, addressing conventions, and security components that together produce an interoperable global aeronautical IP network. The components are defined in Doc 9896.

1. Protocol stack#

ATN/IPS adopts the IETF four-layer Internet model (Doc 9896 §1.1.2).

• Link layer (layer 1-2): local or bilateral choice. ATN/IPS does not mandate a specific link-layer technology. Air-ground subnetworks include VDL Mode 2, AeroMACS, LDACS, and satcom (INMARSAT SwiftBroadband, Iris). Ground networks use Ethernet/IP. The link layer is the domain of FCI standards.

• Internet layer (layer 3): IPv6, mandatory. §1.1.5 states: "This manual adopts IPv6 for Internet layer interoperability. IPv6 is to be implemented in air-ground networks." IPv4 in ground transit networks is permitted but not specified. BGP-4 with extensions is the inter-domain routing protocol. Within a domain, OSPF or other IETF IGPs may be used. Each IPS node has a globally routable, unique IPv6 address prefix (§2.5.2.10).

• Transport layer (layer 4): TCP and UDP. TCP is used for connection-oriented services (SWIM, VoIP signalling, TLS-secured dialogs). UDP is used for ATS applications (CPDLC, ADS-C) via ATNPKT.

• Application layer: ATS and AOC applications. Legacy ATS apps (CM, CPDLC, ADS-C) use the ATN Dialogue Service (DS) over ATNPKT (UDP). SWIM services and newer apps use native TCP/IP interfaces. VoIP (ground-ground and air-ground radio) uses Session Initiation Protocol (SIP) profiled in EUROCAE ED-137.

2. The ATN Dialogue Service (DS) and ATNPKT#

The Dialogue Service is the API between ATS applications and the network. It was designed for ATN/OSI and carried forward to ATN/IPS. It provides five primitives: D-Start, D-End, D-Data, D-Abort, D-P-Abort, and D-Unit-Data. Applications use these primitives without needing to know the transport layer beneath.

ATNPKT is the UDP-based implementation of the Dialogue Service for ATN/IPS (Part III). It encapsulates DS primitives in UDP datagrams with an ATNPKT header that carries the application technology type, QoS class, and session identification. Each application type maps to an IANA-registered UDP port number. DTLS is applied over UDP to secure each dialogue.

The ATNPKT approach preserves backward compatibility: the same CM / CPDLC / ADS-C application code runs unchanged whether the underlying transport is ATN/OSI or ATN/IPS, as long as the DS interface is provided.

3. IPv6 addressing plan#

Each administrative domain in the ATN/IPS internetwork is an Autonomous System (AS) with an ICAO-assigned Autonomous System Number. The appendix to Part I of Doc 9896 defines the AS numbering plan for the ATN/IPS. Each ANSP, CSP, and ACSP manages its own AS or group of ASes.

Aircraft are assigned a globally routable IPv6 address prefix called the Mobile Node Prefix (MNP). The MNP is derived from the aircraft's ICAO 24-bit address and is globally unique across the ATN/IPS. Sub-prefixes (SubMNPs) allow different traffic classes (ATS vs AOC) to be routed over different A/G datalinks.

On the ground, Simple Name Lookup (SNL) provides a lightweight directory mapping Ground Facility Designators (GFDs) to IPv6 addresses, allowing aircraft and ANSPs to discover each other without relying on static address tables.

4. Security components#

Security is mandatory and end-to-end:

• DTLS (Datagram TLS): secures every ATNPKT dialogue against masquerade, modification, and replay. Each dialogue session uses a separate DTLS association.
• TLS: secures TCP-based applications (SWIM, AMHS over IP).
• X.509 certificates: each IPS node (airborne or ground) holds a device certificate signed by a certificate manager (CM) operating under the ATN/IPS PKI defined in Doc 10095.
• Certificate Revocation Lists (CRLs): maintained by the PKI.
• IKEv2: used for IPsec when needed at the ground network layer.
• ROHC (Robust Header Compression): reduces header overhead on bandwidth-constrained A/G subnetworks; key management for ROHC is defined in Part III.

The ATN Baseline 2 safety target (SC4, availability 0.99999) means that the security architecture must also resist denial-of- service attacks, as a successful DoS has a safety implication (Doc 9896 Part IV §2.9.2 and §2.1.2 item iv).

5. Ground domain: nodes and routers#

The Ground IPS Network comprises (§2.5.1, Note):

• One or more CSPs (including ACSPs and Communications Network Providers, CNPs).
• One or more ANSPs.
• One or more ATSUs and aircraft operators.
• The ground part of each A/G datalink.

Ground IPS Router: forwards IPv6 packets not addressed to itself. Ground IPS Host: an end system (ATSU, SWIM server, AMHS node). Ground-Ground Boundary Router (G/G-R): the LISP-capable border router between the ANSP/operator network and the GB-LISP backbone (Part III §3.3.3.6). It registers the ANSP's network prefixes and routes uplinks toward the correct air-ground access network. Air-Ground Boundary Router (A/G-R): the border router between an A/G access network and the GB-LISP backbone (§3.3.3.7). It registers the aircraft's MNP with the LISP mapping system when the aircraft associates with that access network.

6. Airborne domain#

Airborne IPS System: the collection of airborne components providing ATN/IPS services. Includes the airborne IPS router (which forwards packets not addressed to itself) and IPS hosts (cockpit display system, FMS with datalink interface). ARINC 858 Part 1 specifies the airborne IPS system requirements.

The airborne router signals link preference via the AGMI protocol to the ground A/G-R, indicating which subnetworks are available and their relative priority for ATS vs AOC traffic.

7. Organisational model#

Doc 9896 Part IV Chapter 4 defines four actor classes:

• Global Air/Ground CSPs (ACSPs): worldwide coverage (ARINC, SITA, Inmarsat/Viasat).
• Regional ACSPs: sub-regional operators affiliated with a global ACSP.
• Regional ground-ground CSPs: connect ACSPs to ANSPs (EUROCONTROL PENS and PENS2 are the European examples).
• ANSPs, ATSUs, aircraft operators: end users.

Interfaces A (aircraft to ACSP), B (ACSP/CSP to ANSP/operator), and C (CSP to CSP) are the contractual and technical boundaries. Interface A is subject to ICAO standardisation and mandatory compliance wherever ATN/IPS services are provided.

References#

• Doc 9896, Part I, Chapter 1, §1.1.2–§1.1.8 — four-layer model; IPv6, BGP-4, TCP, UDP, TLS, DTLS protocol assignments.
• Doc 9896, Part I, Chapter 2, §2.5.1 — Ground IPS Network composition and general network layer requirements.
• Doc 9896, Part I, Chapter 2, §2.5.2.10 — each IPS node shall have a globally routable, unique IPv6 address prefix.
• Doc 9896, Part II, Chapter 1, §1.1.1 — legacy ATN applications (CM, CPDLC, ADS-C) defined in Doc 9880 can use ATN/IPS.
• Doc 9896, Part III, Chapter 2 — ATNPKT protocol: DS implementation over UDP/DTLS for ATN/IPS.
• Doc 9896, Part IV, Chapter 4, §4.1.3 — organisational model: global ACSPs, regional ACSPs, regional CSPs, ANSPs.
• Doc 9896, Part IV, Chapter 7, §7.2 — ATN/IPS addressing and Mobile Node Prefix (MNP) conventions.
• Doc 9896, Part IV, Chapter 10 — security mechanisms: DTLS, IPsec, PKI, key management.
• Annex 10, Volume III, Chapter 3, §3.4.1 — normative IPv6/IPS choice for the ATN.

For ATN/IPS, "blocks" map most naturally to migration generations and deployment domains rather than to ASBU blocks. This file uses the term "generation" for the evolutionary stages and "domain" for the two principal operational contexts. A mermaid diagram shows the transition flow.

Migration generations#

Generation 0 — ATN/OSI era (pre-2015)#

The network layer uses ISO CLNP; the transport layer uses TP4. These protocols are tunnelled over IPv4 ground networks. Air-ground communications use VDL Mode 2 or ACARS (proprietary VHF/SATCOM). ATN Baseline 1 services (basic CPDLC, ADS-C) are deployed in Europe on this infrastructure; FANS-1/A is used in oceanic and Asia-Pacific regions.

Key limitation: CLNP and TP4 are not COTS; every piece of networking equipment must be purpose-built or licensed. Costs are high and integration with modern IP infrastructure is awkward.

Generation 1 — ATN/IPS transition (approx. 2015-2025)#

Ground-ground networks begin migrating to IPv6. EUROCONTROL PENS and PENS2 implement dual-homed IPv6/IPv4 backbones. AMHS migrates from pure CLNP tunnelling to FMTP (Flight Message Transfer Protocol) over IPv4/IPv6. ATN/IPS ground protocols begin deployment; ATN/OSI remains in service on the air-ground link and for legacy ANSP systems.

ACARS bridging: the ARINC 858 IPS Gateway provides protocol conversion between ACARS-equipped aircraft (FANS-1/A) and ATN/IPS ground systems, so both aircraft populations can be served by a single ground infrastructure.

The second edition of Doc 9896 (pre-2026) governed this period and mandated Mobile IPv6 for mobility. The third edition (2026) replaces this with AGMI/GB-LISP.

Generation 2 — ATN/IPS Baseline 2 (2025 onwards)#

The third edition of Doc 9896 (2026) defines this generation. IPv6 is deployed end-to-end including on the air-ground link. FCI subnetworks (LDACS in continental Europe, Iris SATCOM oceanic) carry the ATN/IPS packets. ATN Baseline 2 services are the operational target: full CPDLC (including 4D trajectory management messages via CPDLC Appendix 5), ADS-C with extended projected profile.

Multilink becomes operational: aircraft use LDACS and SATCOM concurrently, with AGMI/GB-LISP handling seamless handover. The airborne IPS system is certified against ARINC 858 and RTCA DO-379 / EUROCAE ED-262.

The corresponding ASBU thread is COMI-B2 (ATN/IPS data link migration; multi-frequency / satcom data link in oceanic and remote regions).

Generation 3 — full IP integration (from approximately 2031)#

All aeronautical communications (ATS, AOC, SWIM, voice via VoIP) run over a unified ATN/IPS backbone. SWIM services are delivered natively over the ATN/IPS ground network to aircraft and ground systems alike. TBO data exchanges (FF-ICE, FIXM trajectory objects) travel over the same network. Voice uses SIP/VoIP profiled in EUROCAE ED-137.

This aligns with ASBU Block 2/3 SWIM-B2, FICE-B2, and TBO-B3 capabilities.

Deployment domains#

The G/G domain runs on COTS IPv6 infrastructure. Cost and complexity are equivalent to any enterprise WAN. The A/G domain is more constrained: bandwidth is limited, latency varies, and safety certification applies to the airborne IPS system.

ACARS bridging generation (parallel track)#

ACARS (Aeronautical Radio Inc. ARINC 618/620 format) remains in service on millions of aircraft and will not disappear overnight. ARINC 858 Part 2 defines the IPS Gateway that bridges ACARS aircraft to ATN/IPS ground systems. The gateway converts ACARS message formats to ATN/IPS ATNPKT dialogs, allowing FANS-1/A aircraft to communicate with ATN/IPS ANSPs. This bridging function is explicitly part of the ATN/IPS architecture in Doc 9896 Part II and Part IV.

References#

• Doc 9896, Part I, Chapter 1, §1.1.5 — IPv6 adopted; IPv4 not addressed; mandatory in A/G networks.
• Doc 9896, Part IV, Chapter 1, §1.1.1 — third edition intent: Baseline 2 ATS services.
• Doc 9896, Part IV, Chapter 2, §2.1.1 — ATN/OSI experience summary; CLNP tunnelled over IPv4 in current deployment; macro-mobility analogous to mobile roaming.
• Doc 9896, Part IV, Chapter 2, §2.2.1–§2.2.2 — ATN/IPS introduction; CLNP replaced by IPv6; TP4 replaced by TCP/UDP.
• Doc 9896, Part IV, Chapter 4, §4.3 — EUROCONTROL PENS2 as example of high-reliability regional CSP (dual independent networks).
• Annex 10, Volume III, Chapter 3, §3.3.2 — ATN implementation on basis of regional air navigation agreements.

ATN/IPS work is organised along six functional axes. These are not ASBU thread codes but the principal dimensions of ATN/IPS planning, standardisation, and implementation. Each axis is technically distinct; all are interdependent.

Thread 1: IPv6 networking and addressing#

This axis covers the core IP network function: deploying an IPv6 internet that is secure, globally routable, and operates under a coordinated addressing plan.

Key elements:

• IPv6 is mandatory for all ATN/IPS nodes (§2.5.1.3).
• BGP-4 with extensions handles inter-domain routing.
• An ICAO-coordinated AS numbering plan assigns Autonomous System Numbers to administrative domains (Doc 9896, Appendix to Part I).
• Each aircraft receives a globally unique Mobile Node Prefix (MNP) derived from its ICAO 24-bit address.
• SubMNPs allow per-traffic-class routing (ATS vs AOC vs SWIM).
• Simple Name Lookup (SNL) provides lightweight name-to-address resolution, replacing static GFD address tables.
• QoS is implemented via DiffServ (DSCP values assigned by IANA); ROHC reduces header overhead on A/G links.

Planning implications: every ANSP deploying ATN/IPS must obtain an AS number and an IPv6 address allocation, and must establish BGP-4 peering with the regional CSP (e.g. PENS in Europe).

Thread 2: Security and PKI#

This axis covers the end-to-end trust model that makes ATN/IPS safe to use as a carrier for safety-critical communications.

Key elements:

• Each IPS node holds an X.509 device certificate issued under the ATN/IPS PKI. Certificate policy is in Doc 10095.
• DTLS secures every CPDLC/ADS-C dialogue: authentication, integrity, replay protection, optional confidentiality.
• TLS secures TCP-based services (SWIM, AMHS over IP).
• IKEv2 / IPsec may be applied at network boundaries.
• Certificate management (key generation, CSR, upload, CRL) is defined in Doc 9896 Part III Chapter 4.
• Doc 10090 (Security Services) and Doc 10145 (Security Risk Assessment) are companion documents.
• The Baseline 2 safety target (SC4) means denial-of-service resistance is a hard requirement, not an option.

Planning implications: deploying ATN/IPS requires procurement of a PKI-compliant certificate management system, establishment of trust anchors with peer organisations, and a documented security risk assessment per Doc 10145.

Thread 3: Ground-ground backbone#

This axis covers the terrestrial IP network interconnecting ANSPs, CSPs, aircraft operators, and meteorological data services.

Key elements:

• The ground network provides an IPv6 internet service (§2.5.1.1).
• It comprises one or more CSPs (including ACSPs and CNPs), one or more ANSPs, and one or more ATSUs.
• ANSPs connect to the backbone either directly via an ACSP or via a regional CSP.
• EUROCONTROL PENS and PENS2 are the prototype European regional ground-ground CSPs. PENS2 provides high reliability through two fully independent parallel networks (§4.3).
• AMHS migration: the ATSMHS application moves from CLNP-tunnelled X.400 to FMTP over IPv6. EUROCAE ED-262 / RTCA DO-379 profile this migration.
• SWIM services are deployed on this backbone: ANSP SWIM nodes publish services via the IPv6 network to subscribers including other ANSPs, airlines, and meteorological providers.
• Interface C (CSP to CSP) governs inter-CSP connectivity; Interface B (ANSP to CSP) governs ANSP-to-backbone connectivity. Both are subject to Service Level Agreements but not mandatory ICAO standardisation (only Interface A is mandatory).

Thread 4: Air-ground over FCI#

This axis covers the radio-access segment and the mobility architecture that allows aircraft to use multiple datalinks simultaneously.

Key elements:

• ATN/IPS does not specify the link layer; it specifies the minimum requirements the link layer must satisfy.
• Supported A/G subnetworks include VDL Mode 2, AeroMACS (airport surface, covered in Annex 10 Vol III Chapter 7), LDACS (L-band continental, under development), and satellite (Inmarsat SwiftBroadband, Iris over SB-S).
• Annex 10 Vol III §7.3.9 mandates AeroMACS shall transport ATN/IPS (and ATN/OSI over IP) messaging.
• Multilink: each aircraft can signal AGMI preferences for each SubMNP to its A/G-R, directing ATS traffic to one datalink and AOC to another, or failing over automatically.
• GB-LISP: the backbone mobility architecture. A/G-R registers aircraft MNP-to-RLOC mappings in the LISP mapping system; G/G-R routes uplinks using the current best RLOC.
• Interface A (aircraft to ACSP) is subject to ICAO mandatory standardisation; it is defined in ARINC 858 and RTCA DO-379.

Thread 5: Application migration and bridging#

This axis covers the migration of legacy ATN/OSI and ACARS applications onto the ATN/IPS infrastructure.

Key elements:

• CM, CPDLC, ADS-C: defined in Doc 9880 (ATN/OSI). They migrate to ATN/IPS using the ATNPKT DS adapter. The application code is unchanged; only the transport layer beneath the DS API changes.
• ACARS bridging: the ARINC 858 Part 2 IPS Gateway converts ACARS (FANS-1/A) messages to ATN/IPS ATNPKT dialogs. FANS-1/A aircraft remain serviceable in an ATN/IPS ANSP environment.
• ATN Baseline 1 and Baseline 2: both run as application-layer services over ATN/IPS. Baseline 2 adds full CPDLC, 4DTRAD (4D trajectory management), and higher safety classification.
• VoIP: ground-ground telephony and ground-radio communications migrate to SIP/VoIP per EUROCAE ED-137. Carries over the same ATN/IPS ground network.
• SWIM: native IP applications (SWIM services, FF-ICE flight objects in FIXM XML) run directly over TCP/TLS without the ATNPKT adaptation layer. ATN/IPS is their ground transport.

Version management ensures that ATN/IPS and ATN/OSI aircraft can coexist during the transition period. An ANSP may serve both aircraft populations via the IPS Gateway.

Thread 6: Governance and standardisation#

This axis covers the institutional framework that makes ATN/IPS a global interoperable standard rather than a regional one.

Key elements:

• ICAO body: Aeronautical Communications Panel (ACP), which drafts Doc 9896 and proposes Annex 10 amendments.
• SARPS: Annex 10 Vol III Chapter 3 contains the binding requirements; Doc 9896 is the supplementary manual.
• IETF RFCs: ATN/IPS profiles specific RFCs for each protocol layer. RTCA DO-379 / EUROCAE ED-262 publish the profiled RF catalogue.
• EUROCAE / RTCA MOPS: ED-262 / DO-379 (IPS profiles), ED-228 / DO-350 (ATN Baseline 2 SPR/SPE), ARINC 858 (airborne system).
• Regional agreements (PIRGs): Annex 10 §3.3.2 requires implementation on the basis of regional air navigation agreements. EANPG (Europe), APANPIRG (APAC), MIDANPIRG (MID), and GREPECAS (Americas) coordinate.
• Transition timelines: no global mandate date exists; each region sets its own transition schedule through PIRG agreements and the regional Air Navigation Plan.

Cross-thread dependencies#

• Thread 4 (A/G over FCI) depends on Thread 1 (IPv6 addressing) and Thread 2 (PKI/DTLS security).
• Thread 5 (application migration) depends on Thread 1 and Thread 4 for end-to-end packet delivery.
• Thread 3 (ground backbone) depends on Thread 2 (ground-to-ground security) and Thread 6 (SLAs with CSPs).
• SWIM as an application depends on all six threads being in place at ground level and on Thread 4 for airborne SWIM access.

References#

• Doc 9896, Part I, Chapter 1, §1.1.5 — IPv6 and BGP-4 mandates.
• Doc 9896, Part I, Chapter 2, §2.5.1 — ground network composition; QoS; security requirements.
• Doc 9896, Part I, Chapter 2, §2.5.2.10 — globally routable IPv6 prefix per IPS node.
• Doc 9896, Part II, Chapter 1, §1.1.1 — legacy ATN/OSI applications migrating to ATN/IPS.
• Doc 9896, Part IV, Chapter 4 — organisational model; interface types A, B, C.
• Doc 9896, Part IV, Chapter 7 — addressing, SNL, ATNPKT, transport protocols.
• Doc 9896, Part IV, Chapter 10 — security mechanisms, PKI, DTLS, IPsec.
• Annex 10, Volume III, Chapter 3, §3.3.2 — ATN implementation on basis of regional air navigation agreements.
• Annex 10, Volume III, Chapter 7, §7.3.9 — AeroMACS shall transport ATN/IPS messaging.

This file traces one end-to-end ATN/IPS CPDLC session for a transatlantic flight transitioning from LDACS continental coverage to Iris SATCOM over oceanic airspace. It illustrates how ATN/IPS components interact across Thread 4 (A/G over FCI), Thread 5 (application migration), Thread 1 (IPv6 addressing), and Thread 2 (security). All protocol references are to Doc 9896.

Scenario setup#

• Aircraft: B77W registered as ICAO address 0x4CA0B1. Equipped with ARINC 858 IPS system, LDACS transceiver, and Iris SwiftBroadband SATCOM.
• Phase: continental cruise in MUAC (Maastricht), transitioning to Shanwick Oceanic at the MIMKU waypoint.
• Ground systems: MUAC ATSU (ATN/IPS Baseline 2, PENS2-connected) and Shanwick (ATN/IPS Baseline 2, SITA SATCOM-connected).

Step 1: MNP assignment and GB-LISP registration#

On departure, the aircraft's ARINC 858 IPS system has a globally routable IPv6 Mobile Node Prefix (MNP) fd48:ca0b:1::/48 (illustrative; derived from ICAO 24-bit address per Doc 9896 §7.2 addressing conventions). SubMNP fd48:ca0b:1:1::/64 is assigned to ATS traffic; SubMNP fd48:ca0b:1:2::/64 to AOC traffic.

When the aircraft establishes contact with the first LDACS ground station, the Air-Ground Boundary Router (A/G-R) registers the MNP and SubMNPs with the GB-LISP mapping system, with LDACS as RLOC at high priority. The G/G-R at MUAC looks up the MNP in the LISP mapping system and routes uplinks over LDACS.

Step 2: CM Logon (Context Management)#

The pilot initiates a CM Logon on approach to MUAC airspace. This is a two-message exchange via an ATN Dialogue Session (D-Start, D-Data, D-End per the DS API). Over ATNPKT/UDP/DTLS:

1. Aircraft sends a DTLS ClientHello to the MUAC CM server IPv6 address, resolved via Simple Name Lookup (SNL) from the GFD "EDYY" (MUAC designator).
2. DTLS handshake completes: both sides present X.509 certificates, each verifying the other's certificate chain against the ATN/IPS PKI root of trust.
3. CM Logon message is sent via D-Start: aircraft IPv6 address, callsign, flight number, supported applications (CPDLC B2, ADS-C B2), and their transport selectors.
4. MUAC CM server matches the callsign to the active flight plan (a safety requirement per §5.1.15) and returns a positive CM Logon Response listing MUAC's supported applications.
5. The ATN Dialogue Session is closed after the exchange.

MUAC now holds: callsign-to-MNP binding; CPDLC and ADS-C transport addresses for this flight.

Step 3: Active CPDLC session (MUAC)#

MUAC opens a CPDLC session (D-Start) to the aircraft:

• CDA (Current Data Authority) session established.
• Routine level clearances and handoff instructions are exchanged over D-Data primitives.
• Each D-Data is one ATNPKT datagram, secured with DTLS.
• ATNPKT includes the DSCP class CS4 (critical routing) for ATS traffic, ensuring priority over LDACS.

Step 4: Multilink transition at MIMKU#

Approaching MIMKU, the aircraft's AGMI signals to the A/G-R that Iris SATCOM has established a connection with higher priority for oceanic ATS traffic (SubMNP fd48:ca0b:1:1::/64). The A/G-R updates the LISP mapping system: new RLOC for the ATS SubMNP points to the Iris SATCOM ACSP gateway.

The G/G-R at MUAC (and shortly Shanwick) automatically reroutes uplinks to the ATS SubMNP via the Iris SATCOM path. The CPDLC DTLS session at the application layer is unaffected: DTLS operates end-to-end and the mobility is transparent below the transport layer. There is no CPDLC timeout or retransmission caused by the handover. This is the operational benefit of AGMI/GB-LISP multilink.

Step 5: NDA session and transfer to Shanwick#

MUAC initiates a CM Contact (NDA: Next Data Authority) to instruct the aircraft to logon to Shanwick. The aircraft performs a CM Logon with Shanwick over Iris SATCOM / ATN/IPS. Shanwick establishes a CPDLC session (NDA). At the transfer point, MUAC closes the CDA session; Shanwick becomes the new CDA.

From Shanwick's perspective, the aircraft is just another IPv6 node whose MNP it can address via the GB-LISP backbone (now routing over Iris SATCOM RLOC). No ACARS-style service-level protocol is needed.

Key observations#

• The entire end-to-end flow uses COTS IPv6 routing and standard IETF protocols (UDP, DTLS, LISP) below the ATS application.
• The ATN Dialogue Service preserves the CPDLC application API, so avionics and ground systems need not change their application logic when migrating from ATN/OSI to ATN/IPS.
• Security is end-to-end (DTLS per dialogue), not hop-by-hop. A compromised intermediate router cannot inject or modify CPDLC messages without breaking the DTLS authentication.
• Multilink transition is transparent to the controller and pilot. Operationally it is invisible; technically it requires AGMI, GB-LISP, and LISP mapping system to be deployed end-to-end.

References#

• Doc 9896, Part IV, Chapter 5, §5.1 — CM Logon procedure: callsign-to-network-address binding, safety requirement for flight plan match.
• Doc 9896, Part IV, Chapter 5, §5.2 — CPDLC: CDA, NDA, and DDA session model; DTLS-secured sessions.
• Doc 9896, Part III, Chapter 2 — ATNPKT protocol: D-Start / D-Data / D-End over UDP/DTLS.
• Doc 9896, Part IV, Chapter 7, §7.2 — ATN/IPS addressing; MNP and SubMNP conventions.
• Doc 9896, Part III, Chapter 3, §3.3 — GB-LISP architecture; A/G-R and G/G-R roles.
• Doc 9896, Part IV, Chapter 8, §8.2 and §8.3 — AGMI and multilink operation; SubMNP preference signalling.

ATN/IPS deployment requires a set of enabling conditions that go beyond the procurement of networking equipment. Each category below identifies what must be in place before the network can carry safety-critical communications at the required performance level.

1. CNS infrastructure#

Ground network (G/G domain)#

• IPv6-capable routers and switches throughout ANSP and CSP networks. Replacement of legacy CLNP/IPv4 tunnelling.
• BGP-4 peering with the regional ground-ground CSP (e.g. PENS/ PENS2 in Europe). BGP peering agreements, including routing policy and prefix filters.
• LISP mapping system deployment across the CSP/CNP domain for the GB-LISP mobility and multilink architecture.
• SNL (Simple Name Lookup) server deployment for GFD-to-IPv6 address resolution.
• AMHS migration from legacy OSI X.400 to FMTP over IPv6.

Air-ground subnetworks (A/G domain)#

• VDL Mode 2 network: already deployed in continental Europe and major global hubs; supports legacy ATN/OSI and ATN/IPS.
• AeroMACS: IEEE 802.16e-based surface communications at airports. Annex 10 Vol III §7.3.9 requires AeroMACS to carry ATN/IPS.
• LDACS (L-band Digital Aeronautical Communications System): the continental FCI datalink under final standardisation for Annex 10. Not yet widely deployed; targeted for continental ATN/IPS B2 operations.
• Iris SATCOM (Inmarsat/Viasat): provides oceanic and remote area coverage. SESAR 3 JU Iris project certifies this for ATN Baseline 2. In initial operational deployment from 2025.
• HF data link: legacy fallback; not an ATN/IPS primary carrier.

2. Security infrastructure (PKI)#

• Deployment of an ATN/IPS PKI compliant with Doc 10095. Each administrative domain must establish its certificate manager and join the trust hierarchy.
• X.509 certificate issuance for every IPS node: ANSP servers, CSP gateways, airborne IPS systems.
• Certificate Revocation List (CRL) distribution infrastructure.
• Key management: over-the-air key update procedures defined in Doc 9896 Part III Chapter 4 must be operationalised.
• Security risk assessment per Doc 10145 for each deployment.
• DTLS-aware firewall and intrusion-detection in ANSP networks; denial-of-service resistance at network boundaries.

3. Avionics and fleet equipage#

• ARINC 858 Part 1 compliant Airborne IPS System: includes the IPv6 router, AGMI endpoint, DTLS implementation, certificate store, and ROHC.
• RTCA DO-379 / EUROCAE ED-262 IPS profile compliance.
• Supplementary Type Certificate (STC) or equivalent aircraft certification for the airborne IPS system.
• Compatible cockpit interface for CPDLC B2 applications (ATSU display, CPDLC message set per Doc 4444 Appendix 5).
• FANS-1/A fleet: ARINC 858 Part 2 IPS Gateway on ground enables interoperability without retrofitting; no avionics change on legacy aircraft.

4. Regulatory and certification framework#

• ICAO SARPS: Annex 10 Vol III Chapter 3 (currently in force); applicable to all ICAO Contracting States.
• Regional air navigation agreement (required by Annex 10 §3.3.2) specifying which States/regions adopt ATN/IPS and the timeline.
• Airworthiness regulations: EASA CS-ACNS (Communication, Navigation, Surveillance) and equivalent (FAA AC, etc.) for approval of the airborne IPS system.
• ATN Baseline 2 SPR/SPE: EUROCAE ED-228B / RTCA DO-350B define the operational safety and performance requirements that frame the certification basis.
• Ground system safety assurance: EUROCAE ED-78A / RTCA DO-264A for ATS data link service approval.

5. Procedures and PANS#

• Doc 4444 (PANS-ATM) procedures for CPDLC Baseline 2 operations: Chapter 14 data link procedures; Appendix 5 CPDLC message set.
• ATC training for CPDLC B2: handling 4D trajectory management messages, loss-of-comm contingency, dual CDA/NDA handover.
• Pilot training for CPDLC B2 and ADS-C periodic/event contracts.
• ANSP operational procedures for multilink monitoring and fallback to voice communication.
• Regional supplementary procedures (Doc 7030) for CPDLC in specific FIRs (e.g. ICAO EUR Doc 015 for European data link).

6. Standards and industry documents#

Key normative and guidance documents beyond ICAO:

• EUROCAE ED-262 / RTCA DO-379: IPS profiles of IETF RFCs.
• EUROCAE ED-228B / RTCA DO-350B: ATN Baseline 2 SPR/SPE.
• ARINC 858 Part 1 (Airborne IPS System), Part 2 (IPS Gateway), Part 3 (CIRI radio interface).
• EUROCAE ED-137 series: VoIP for ATM (ground radio, telephony).
• Doc 9869 (PBCS Manual): RCP/RSP requirements for data link.
• Doc 10095, Doc 10090, Doc 10145: ATN/IPS security trilogy.

7. Institutional and inter-State#

• Bilateral SLAs between ANSPs for cross-border CPDLC continuity. An aircraft entering a new FIR must be able to transfer its CPDLC session without re-logging onto ATN/IPS infrastructure.
• Inter-ANSP CM forwarding: OLDI LOF (Logon Forward) message enables the receiving ANSP to have context before the aircraft crosses the FIR boundary.
• Interconnection agreements between ANSPs and regional CSPs (Interfaces B and C; not mandated but governed by SLAs).
• Global ACSP interconnection agreements: global ACSPs (ARINC, SITA, Inmarsat/Viasat) must be fully interconnected on a peer-to-peer basis (§4.1.3(a)) so any aircraft can communicate with any ANSP via any ACSP.
• PIRG coordination: regional decision on which ATN standard (OSI or IPS) applies; transition timeline agreements.
• ICAO Communications Panel (ACP) oversight of Doc 9896 amendments and liaison with EUROCAE/RTCA/IETF.

References#

• Annex 10, Volume III, Chapter 3, §3.3.2 — regional air navigation agreement requirement.
• Annex 10, Volume III, Chapter 7, §7.3.9 — AeroMACS ATN/IPS carriage requirement.
• Doc 9896, Part I, Chapter 2, §2.5.1.9 — ATN/IPS ground network shall be secure against threats identified by security risk assessment.
• Doc 9896, Part IV, Chapter 4, §4.1.3 — global ACSP interconnection requirement on peer-to-peer basis.
• Doc 9896, Part IV, Chapter 9 — air safety and ATN/IPS; safety objectives and operational hazard classification.
• Doc 9896, Part IV, Chapter 10 — security mechanisms; PKI; DTLS; Doc 10095/10090/10145 references.
• Doc 9869 (Performance-based Communication and Surveillance (PBCS) Manual) — RCP/RSP specifications applicable to CPDLC data link operations (authoritative source — not in local library).

Performance lens#

ATN/IPS is infrastructure, not an operational improvement in itself. Its performance objectives are framed as enabling conditions: delivering the communications service quality that allows other ASBU capabilities (CPDLC B2, SWIM, FF-ICE, TBO) to achieve their operational benefits. The primary KPA is interoperability; security and safety are hard constraints rather than improvement targets.

The performance framework for ATN/IPS data link draws on:

• Doc 9869 (PBCS Manual): Required Communication Performance (RCP) and Required Surveillance Performance (RSP) specifications.
• EUROCAE ED-228B / RTCA DO-350B: ATN Baseline 2 SPR/SPE, which define safety class and performance targets.
• Doc 9896 Part IV §2.9.2: loss-of-communication target SC4; availability 0.99999.

KPA contributions#

The matrix below scores each KPA for ATN/IPS across the four migration stages (Generation 0 = ATN/OSI baseline; Gen 1 = ground migration; Gen 2 = ATN/IPS B2; Gen 3 = full IP integration). Scoring: 1 = some benefit, 2 = clear benefit, 3 = primary driver.

The narrative below explains the scoring.

Interoperability#

Primary driver from Gen 2. ATN/IPS eliminates proprietary networking protocols (CLNP, TP4) and replaces them with COTS IPv6. An ANSP with an IPv6 ground network automatically achieves network- layer interoperability with any other ATN/IPS participant, regardless of vendor. This is the single largest structural benefit. In Gen 0, interoperability requires expensive custom CLNP gateways. In Gen 3, any application (CPDLC, SWIM, FF-ICE, AOC) runs over the same IP backbone with no protocol translation.

Safety#

Clear benefit from Gen 2; primary driver from Gen 3. The ATN Baseline 2 SPR (SC4) provides a formally certified safety case for datalink communications for the first time. Multilink reduces communication outage risk: a single datalink failure does not immediately trigger a loss-of-comm event because the second datalink continues. ATNPKT inactivity timers are tuned to match the RCP/RSP outage duration limit. In Gen 0, ATN Baseline 1 is classified SC5 (no safety implication) so there is no formal safety assurance on the communication service.

Security#

Minimal in Gen 0; primary driver from Gen 2. ATN/OSI has no end-to-end security by default; the network relies on physical separation and access control. ATN/IPS mandates DTLS for every CPDLC and ADS-C dialogue and requires PKI-based device authentication. The Baseline 2 SC4 hazard classification means denial-of-service resistance is a hard requirement: a successful DoS has a safety implication and must be addressed in the security design. From Gen 2, every ATN/IPS node must pass a security risk assessment (Doc 10145).

Capacity#

Moderate benefit from Gen 1; growing through Gen 3. ATN/IPS enables COTS IP hardware, which is typically much cheaper and denser than custom CLNP equipment. Ground-ground bandwidth increases as ANSPs replace legacy OSI links with standard Ethernet /MPLS backbones. In the air, multilink doubles effective A/G bandwidth for datalink. ROHC compresses protocol headers, increasing effective throughput on constrained LDACS and VDL2 channels. In Gen 3, SWIM and FF-ICE generate substantially more data traffic than legacy CPDLC/ATSMHS; only an IP backbone can handle this at scale.

Cost-effectiveness#

Significant benefit from Gen 2. Replacing custom CLNP infrastructure with COTS IPv6 networking equipment reduces both capital expenditure (off-the-shelf routers, switches, firewalls) and operating expenditure (wider skills market; standard management tools; commodity hardware replacement). PENS/PENS2 in Europe has already demonstrated significant cost reductions in inter-ANSP communications versus the legacy AFTN/AMHS network.

Flight efficiency and predictability#

Indirect, growing from Gen 2. ATN/IPS does not itself improve flight efficiency or predictability. It enables CPDLC B2 (which enables RTA and 4D trajectory management) and SWIM (which provides the information sharing for DCB and A-CDM). Without reliable, interoperable, low-latency data link, the trajectory management and information exchange required for TBO and FF-ICE cannot function. In Gen 3, the full IP backbone carrying SWIM-distributed trajectory and flow information is the enabling condition for the flight efficiency gains of Block 2/3 ASBU.

RCP/RSP performance targets#

The PBCS manual (Doc 9869) defines RCP specifications for CPDLC datalink. Two commonly applied specifications:

ATN/IPS with multilink provides the communications performance needed to meet RCP 130 in continental airspace (LDACS or VDL2) and RCP 240 in oceanic airspace (Iris SATCOM). Meeting RCP is a pre-condition for deploying CPDLC B2 services in a given airspace.

References#

• Doc 9896, Part IV, Chapter 2, §2.9.2 — Baseline 2 SC4 hazard classification; availability target 0.99999.
• Doc 9896, Part I, Chapter 2, §2.5.1.9 — ground network security against identified threats.
• Doc 9869 (Performance-based Communication and Surveillance (PBCS) Manual) — RCP/RSP specifications for data link operational performance (authoritative source — not in local library).
• Annex 10, Volume III, Chapter 3, §3.4.6 — ATN shall provide communication in accordance with prescribed RCP and RSP specifications.

Two timelines to keep distinct#

1. Doc 9896 edition timeline — when ICAO published or revised the ATN/IPS manual.
2. Operational deployment timeline — when networks and services were or are expected to become operational.

A regional or national implementation schedule is a third timeline; it references both Doc 9896 provisions and PIRG agreements.

Doc 9896 and ATN/IPS standards evolution#

PENS / EUROCONTROL ground network milestones#

LDACS standardisation milestones#

Key implications for planning#

When reading a date in an ATN/IPS document, check which type it is:

• "Amendment 88-A (2013)" — Annex 10 amendment date (normative).
• "Third Edition (2026)" — Doc 9896 publication date.
• "Baseline 2 from 2025" — operational service deployment date (regional, not global mandate).
• "LDACS SARPs by 2028" — projected standardisation milestone (not yet confirmed, subject to ICAO Council approval).

States implementing ATN/IPS should express their plans in terms of both the applicable Doc 9896 edition and the regional PIRG agreement timeline — not Doc 9896 dates alone.

References#

• Annex 10, Volume III, Amendment 83, Amendment record table — initial IPS provisions added 10 March 2008.
• Annex 10, Volume III, Amendment 88-A, Amendment record table — ATN/IPS SARPs added; §3.4.10 multilink requirement.
• Doc 9896, Third Edition (2026), line 1 — "Third Edition (Advance unedited) - 2026."
• Doc 9896, Part IV, §2.1.1 — ATN/OSI experience summary; Iris SATCOM began ATN/OSI Baseline 2 operations in 2025.
• Doc 9896, Part IV, Appendix B — Mobile IPv6 was the mandated approach in the second edition; replaced by AGMI/LISP in the third edition.

Primary ICAO documents#

• Doc 9896 (Manual on the ATN using IPS Standards and Protocols), Third Edition (2026, advance unedited). The definitive technical manual for ATN/IPS. Four parts: technical specifications (I), IPS applications (II), dialogue service and ATNPKT (III), and guidance material (IV). Supplements Annex 10 Vol III, Chapter 3.

• Annex 10 — Aeronautical Telecommunications, Volume III (Communication Systems), Part I, Chapter 3. Contains the normative SARPs for the ATN. §3.4.1 (OSI or IPS choice), §3.3.2 (regional agreements), §3.4.10 (multilink mandate). Amendments 83 (2008) and 88-A (2013) introduced and expanded ATN/IPS provisions.

• Annex 10, Volume III, Chapter 7 — AeroMACS SARPs; §7.3.9 requires AeroMACS to transport ATN/IPS and ATN/OSI over IP.

• Doc 9880 (Manual on Detailed Technical Specifications for the ATN using ISO/OSI Standards and Protocols). Defines the legacy ATN/OSI from which applications migrate. CM, CPDLC, ADS-C application specifications reference this document; Doc 9896 provides the IPS-layer equivalents. (Authoritative source — not in local library.)

• Doc 9854 (Global ATM Operational Concept). Provides the KPAs used to frame the communications performance goals.

• Doc 9869 (Performance-based Communication and Surveillance (PBCS) Manual). RCP and RSP specifications for data link operations; defines RCP 130 and RCP 240 applicable to CPDLC services over ATN/IPS. (Authoritative source — not in local library.)

• Doc 10095 (Manual on Public Key Infrastructure (PKI) Policy for Aeronautical Communications). ATN/IPS PKI certificate policy; companion to Doc 9896 security provisions. (Authoritative source — not in local library.)

• Doc 10090 (Manual on Security Services for Aeronautical Communications). Security services for ATN/IPS; companion. (Authoritative source — not in local library.)

• Doc 10145 (Manual on Security Risk Assessment for Aeronautical Communications). High-level security risk assessment for ATN/IPS; referenced from Doc 9896 §2.5.1.9 and Part IV Ch 10. (Authoritative source — not in local library.)

EUROCAE / RTCA standards#

• EUROCAE ED-262A / RTCA DO-379A — IPS Profiles: IETF RFC profiles required for ATN/IPS interoperability. Referenced from Doc 9896 §2.2.2 and §2.2.10. (Authoritative source — not in local library.)

• EUROCAE ED-228B / RTCA DO-350B — ATN Baseline 2 Safety and Performance Requirements (SPR) and Safety and Performance Evaluation (SPE). Provides the SC4 operational hazard classification. Outage Duration Limit removed; States define own limits. (Authoritative source — not in local library.)

• EUROCAE ED-137 series — VoIP for ATM systems (Volumes 1-5). Ground radio, telephony, and recording over the ATN/IPS ground network. Referenced from Doc 9896 Part II Chapter 2 and Part IV Chapter 13. (Authoritative source — not in local library.)

ARINC standards#

• ARINC 858 Part 1 — Airborne IPS System: functional requirements for the aircraft-side ATN/IPS router, security, AGMI, and radio interface. (Authoritative source — not in local library.)

• ARINC 858 Part 2 — IPS Gateway: protocol conversion between ACARS (FANS-1/A) aircraft and ATN/IPS ground systems. (Authoritative source — not in local library.)

• ARINC 858 Part 3 — Common IPS Radio Interface (CIRI): interface between the airborne IPS router and the radio access network. (Authoritative source — not in local library.)

Authoritative external sources#

• https://www.icao.int/safety/acp/ - ICAO Aeronautical Communications Panel; body responsible for Doc 9896 and ATN/IPS SARPs
• https://store.icao.int/ - ICAO Document Store; source for Doc 9896, Annex 10 Vol III, Doc 9869, Doc 9880, Doc 10095, Doc 10090, Doc 10145
• https://www.eurocontrol.int/concept/future-communications-infrastructure - EUROCONTROL FCI programme overview; LDACS and AeroMACS deployment timelines
• https://www.sesarju.eu/projects/iris - SESAR 3 JU Iris project; Viasat/Inmarsat SATCOM ATN/IPS datalink for oceanic/remote areas
• https://www.eurocontrol.int/publication/pens-connection-guidelines - EUROCONTROL PENS connection guidelines; reference for European ground-ground CSP
• https://www.rtca.org/ - RTCA; source for DO-379, DO-350, DO-264 standards
• https://www.eurocae.net/ - EUROCAE; source for ED-262, ED-228, ED-137, ED-303 standards