DDLSNSD 2029 DRAFT_July 2025 (7-11-25).docx

Domestic Datalink Services (DDLS) Network Service Description (DDLSNSD)

DRAFT

July 2025 Federal Aviation Administration 800 Independence Avenue SW Washington, DC 20591

RECORD OF CHANGES

TABLE OF CONTENTS

LIST OF TABLES

Table 5-1. Verification Requirements Traceability Matrix 41

LIST OF FIGURES

Figure 3-1. Data Communications System – DDLS Boundaries 13

2 SCOPE

This document provides the requirements for the Domestic Datalink Services (DDLS). The purpose of this document is to define the network service requirements for the FAA’s Data Communications System (DCS).

2.1 Background

As a consequence of decisions made at the International Civil Aviation Organization (ICAO) Aeronautical Navigation Commission (ANC) 11th meeting, the Federal Aviation Administration (FAA) initiated a harmonization effort with Europe (as represented by Eurocontrol), known as the Future Communications Study (FCS), to explore the possibilities for a harmonized direction for the future Air Traffic Control (ATC) Air/Ground (A/G) Communication systems of the world. Results to date have indicated that the United States (U.S.) will continue using the Very High Frequency (VHF) spectrum for domestic air traffic control communications, which the FAA expects will satisfy these needs beyond the 2030 timeframe.

Current operations utilizing data link in ATC use existing commercial data communication services. These services include Future Air Navigation Services (FANS) which supports Air Traffic Control in U.S. Oceanic airspace, Aircraft Communications and Reporting System (ACARS) which currently supports Pre-Departure Clearance application in some terminal environments. The U.S. Roadmap accommodates user desires to utilize existing VHF capabilities and equipment to provide aeronautical data link services, assumes that the VDL Mode 2 technology will support data communications services in the U.S.

2.2 Purpose

This document provides a requirements basis for the air/ground communications message delivery function to support acquisition decisions. This document provides a service description for the data communications infrastructure needed to support a set of services described in the FPR and RTCA SC-214 System Performance Requirements (SPR), and the system level requirements needed to support the acquisition process. This document serves as the focal point for all service level technical requirements affecting the development and evolution of the system necessary to the A/G DCS for Air Traffic Control. This document allocates FAA requirements that apply to the communications service provider(s). The communications capability will accommodate FANS-equipped aircraft and provide a path towards the Next-Generation Air Traffic System (NextGen), as well as possible future Internet Protocol-based (IP-based) A/G communication.

2.3 Scope

This document recognizes the avionics element as integral to system operation. However, avionics are discussed only as they affect the ground system design. The scope of the document is focused on the ground system. The aircraft systems are based on other standards documents that are available elsewhere.

This document covers the FANS network Tower and En Route environments over the VDL Mode 2 subnetwork service. This document is limited to the requirements for the Domestic Datalink Services (DDLS) of the Data Communications System.

2.4 Document Organization

· Section 1 states the purpose and scope of this specification, its relationship to other program source requirements documents, and the driving influences that must be considered in satisfying those requirements. It also defines terminology that provides the basis for consistent references in developing system level requirements.

Section 2 defines the applicable reference documents cited in this specification.

Section 3 specifies the DDLS general requirements.

Section 4 specifies the DDLS service requirements.

Section 5 defines the verification process for the DDLS.

Appendix A provides a list of acronyms Appendix B Provides a list of DCL Airports Appendix C En Route Service Volumes Appendix D details supplemental En Route coverage requirements.

2.5 Definitions

Communications Service Provider: An existing provider of VDL Mode 2 air/ground communications to aircraft cockpits.

Jeopardy Condition: This exists when a function is still available, but redundancy needed to meet reliability, maintainability and availability requirements is not.

Maintenance User: A person responsible for the proper operation of infrastructure of the FAA system.

Monitoring Service: The provision of status information on Network Service elements to assist in determination of air traffic control operational impacts due to Network Service infrastructure issues.

Network Service: The provision of air/ground data communications messaging in support of air traffic control communications.

Operational User: A person who is responsible for managing and/or controlling aircraft in the airspace.

Scheduled Maintenance: A planned and FAA-approved interruption or degradation of service. It includes all FAA-approved Preventative Maintenance, Corrective Maintenance, Emergency Maintenance, and upgrade interruptions of service. It excludes any length of time that exceeds the duration of an approved interruption or degradation.

Sensitive Flight Data: Sensitive Flight Data is all flight data associated with the classified and sensitive unclassified missions conducted in the NAS for the purposes of national defense, homeland security, intelligence and law enforcement. Sensitive Flight Data is designated Sensitive Unclassified Information (SUI).

Sensitive Unclassified Information: A designation for unclassified information that requires safeguarding or dissemination controls, pursuant to and consistent with applicable law, regulations, and government-wide policies (Executive Order 13556). SUI may include information that may qualify for withholding from the public under the Freedom of Information Act (FOIA).

2.6 Assumptions

The data communications system will support the current operational concepts as well as the transition to NextGen operational concept.

The DCS will use the VDL Mode 2 technology as an initial RF link.

The VDL-2 implementation will support Ground-requested Air-initiated Handoff function.

Data services will be provided using the VHF band (118 - 137 MHz).

VHF spectrum will be available to support air-ground voice and data communications.

If necessary, existing voice frequencies within the VHF band will be reorganized to provide a clear sub-band for VDL 2 operation, while maintaining 25 kHz voice channels.

Air/ground information security (i.e., authentication, encryption, etc) will be accomplished as part of the Internet Protocol Suite in accordance with applicable RTCA documentation, when implemented.

The VDL network will be managed to assure that ATC communications performance requirements are met (i.e., other data traffic does not degrade ATC data performance below minimum levels).

Voice A/G communications will continue to be provided by the FAA and will not be dependent on data communications. The voice system will meet the current performance requirements at least through the timeframe of this program.

The FAA operates the NAS Enterprise Security Gateway (NESG).

3 APPLICABLE DOCUMENTS

The following documents form a part of this Service Description (SD) to the extent specified herein. Secondary references, or those documents referenced by documents contained in this section, also form a part of this SD to the extent specified by applicable sections of the documents referenced directly in this section.

3.1 Government Documents

3.1.1 FAA Specifications

Sections[footnoteRef:3] [3: Sections referenced are used at a minimum. Others may apply.]

DOT/FAA/CT-03/05

HF-STD-001

JAVA Messaging Service Description Document (JMSDD) Latest Version

JAVA Messaging Service Description Document (JMSDD) Latest Version

3.1.2 FAA Orders

FAA Order 7210.632

3.1.3 Other FAA Documents

FPR

NAS-PR-0101

3.1.4 Other Government Documents

3.2 Non-Government Documents

3.2.1 ICAO Standards

- Volume III

- Volume III

- Volume V

3.2.2 Industry Standards

Latest Version 2.0, 3.1, 3.2, 3.4, 3.5, 3.10, 3.11

3.3 Order of Precedence

When the requirements of this document and referenced applicable documents are in conflict, this document has precedence over all documents referenced herein.

If either two or more referenced applicable documents are in conflict or two or more sections of this document are in conflict, AJW should be notified to resolve the conflict.

3.4 Availability of Documents

3.4.1 FAA Documents

Copies of FAA specifications, standards, and publications may be obtained from the Contracting Officer, FAA, 800 Independence Avenue SW, Washington, DC 20591. Requests should clearly identify the desired material by number and state the intended use of the material.

3.4.2 Federal Documents

Copies of federal publications may be obtained from the U.S. Government Printing Office, 710 North Capitol Street, Washington DC, 20401, by calling (202) 512-0132, or through the web site http://bookstore.gpo.gov/.

3.4.3 International Civil Aviation Organization (ICAO) Documents Copies of ICAO documents may be obtained from the ICAO Library, 999 University Street, Montreal, Quebec H3C 5H7, Canada.

Note: For current working documents that are not final products, inquire at ICAO web site http://www.icao.int/anb/panels/acp/repository.cfm.

3.4.4 RTCA, Inc. Documents

Copies of RTCA, Inc. documents may be obtained from RTCA, Incorporated, 1828 L Street N.W., Suite 805, Washington, DC 20036-4001, by phone (202) 833-9339, or through the web site http://www.rtca.org.

3.4.5 ARINC, Incorporated Documents

Copies of ARINC documents may be obtained from SAE Industry Technologies Consortia, Airlines Electronic Engineering Committee (AEEC), by phone 443.534.7439, or through the web site AEEC Material - ARINC IA | SAE ITC (sae-itc.com).

3.4.6 International Organization for Standardization (ISO) Documents Copies of ISO documents may be obtained from ISO Central Secretariat, 1, ch. de la Voie-Creuse, Case postale 56, CH-1211 Geneva 20 Switzerland, by phone +41 22 749 01 11, or through the web site http://www.iso.org/iso/en/ISOOnline.frontpage.

3.4.7 International Telecommunication Union (ITU) Documents

Copies of ITU documents may be obtained from International Telecommunication Union, Sales and Marketing Division, Place des Nations, CH-1211 Geneva 20 - Switzerland, by phone +41 22 730 5194, via email to sales@itu.int, or through the web site http://www.itu.int/ITU-T/publications/index.html.

3.4.8 Internet Engineering Task Force (IETF) Documents

Copies of Internet Engineering Task Force documents may be obtained through the web site http://www.ietf.org.

3.4.9 National Institute of Standards and Technology (NIST) Documents Copies of National Institute of Standards and Technology documents may be obtained through the web site http://csrc.nist.gov/publications/PubsSPs.html.

4 GENERAL REQUIREMENTS

When used in this document, the word “must” refers to an explicit requirement of a system component or the complete system.

4.1.1 Interfaces

4.1.1.1 Internal Interfaces

The internal interfaces are the purview of the DDLS provider. This includes any interfaces with other network service providers.

4.1.1.2 External Interfaces

The key DDLS external interfaces can be identified as follows:

1. Ground Radio / Aircraft Radio Network Service via NAS Enterprise Security Gateway DDLS Monitoring / NESG Data Link Dispatch / NESG DDLS / En Route Automation Modernization (ERAM)

4.2 System Functional Requirements

The Data Communications System for the Communications Service Provider functional requirements are described in the following subsections.

4.2.1 Messaging

4.2.1.1 General

1. The DDLS must support the exchange of data messages between ground and aircraft systems.

1. The DDLS must communicate Air Traffic Service (ATS) messages with all qualified aircraft that desire ATS data communications, regardless of existing AOC service provider affiliation. Qualification is determined by appropriate equipage and certification for operation.

Where the DDLS interfaces with the FAA Telecommunications Network, the DDLS must comply with the FAA Telecommunications Services Description for the relevant telecommunications requirements.

The Data Communications Network Service must comply with the ERAM-TBD IRD.

The Data Communications Monitoring and Control (M&C) function must comply with the interface TBD.

The DDLS Monitoring data interface to the FAA TBD must comply with TBD. Service Delivery Point

4.2.1.2 Service Delivery Point

c. The Network Service must provide redundant service delivery points to the FAA NESGs, so that failure of one interface or associated telecommunication link(s) will not cause an outage for the most stringent RMA performance level ordered.

4.2.2 Upgradeability

d. When upgrading service performance for a volume of airspace, the service must not be interrupted to the point where an outage would be declared for the lower performance level, unless the FAA expressly agrees to a longer outage beforehand.

4.2.3 Use of FAA Facilities

The following sections under 3.2.3 apply to equipment, if any, that is installed within FAA facilities. Equipment that is installed within FAA facilities must comply with Order 6030.20F, Electrical Power Policy, Order 6950.2D, Electrical Power Policy Implementation at National Airspace System Facilities, and Standard FAA-STD-019e, Lightning and Surge Protection, Grounding, Bonding and Shielding Requirements for Facilities and Electronic Equipment.

It is the vendor’s responsibility to integrate any equipment into non-FAA facilities.

4.2.3.1 Physical Requirements

1. DDLS equipment must comply with the mechanical requirements of FAA-G-2100H, Sections 3.1.2, 3.2.1, 3.2.2, 3.2.4, 3.3.1, and 3.3.3.

1. DDLS equipment must comply with the electrical requirements of FAA-G-2100H, Sections 3.1.1, 3.2.6, and 3.3.1.4.

1. Cabling interfacing to FAA equipment or facilities must comply with NFPA Standard 70, National Electrical Code.

1. DDLS equipment must comply with requirements defined in paragraph 3.3.5 Personnel Safety and Health of FAA-G-2100H.

1. DDLS equipment must comply with provisions of Chapter 12 of FAA HFDS requirements for Personnel Safety.

1. DDLS equipment must be free of asbestos.

1. DDLS equipment must be free polychlorinated biphenyls (PCBs).

1. DDLS equipment must be free of lead paint.

1. DDLS equipment must be free of Class I ozone-depleting substances.

1. DDLS equipment must be free of mercury with the exception of mercury that may be present in the liquid crystal display (LCD) of computer monitors in trace amounts.

1. DDLS equipment must be free of lead with the exception of lead that is used in the manufacture of circuit boards and monitors.

1. The use of hazardous materials in the design, manufacture, and installation must comply with 29 CFR 1910 Sub Part H – Hazardous Materials.

1. DDLS equipment must conform to the requirements for certification, approval and listing by Nationally Recognized Testing Laboratories of 29 CFR 1910 subpart S, 1910.303.

1. DDLS equipment maintainer access must be in accordance with 29 CFR 1910.303 (g) (1,2) Electrical.

4.2.3.2 Electromagnetic Compatibility Requirements

1. DDLS equipment must meet electromagnetic compatibility requirements referenced in FAA-G-2100H, Section 3.3.2.

1. Electromagnetic emission and susceptibility of developed DDLS equipment must meet the requirements of MIL-STD-461F, Section 5.3. For the purposes of requirement applicability, the DDLS equipment is assumed to be “Ground, Army”.

1. Electromagnetic emission and susceptibility of DDLS RF equipment must meet the requirements of MIL-STD-461F, Section 5.3. For the purposes of requirement applicability, the DDLS equipment is assumed to be “Ground, Army”.

1. All commercial equipment must meet the requirements of Federal Communications Commission FAA Class A, (CFR Title 47 Part 15) or better.

4.2.3.3 NAS Compatibility Requirements

1. The installation and operation of DDLS equipment must produce no adverse impact upon the other NAS subsystems with which it interfaces.

4.2.4 Incident Investigation

The FAA recognizes that the DDLS will likely monitor additional information as needed to manage the network. The FAA would like this information to be available to investigators in case of communications-related incident.

1. The Network Service and the Monitoring Service must maintain recorded data for 45 days.

The Network Service and the Monitoring Service must retain recorded data involved in an incident investigation in accordance with FAA Order 7210.632 Chapter 4.

4.2.5 Network Service and Monitoring Service Security

The data communications Preliminary Security Risk Assessment was performed and determined that Data Communications system was a moderate-impact system. These requirements in this section were adapted from the National Institute of Standards and Technology (NIST) Special Publication 800-53 set of controls for moderate-impact information systems in accordance Federal Information Processing Standard (FIPS) Publication (Pub) 200, Minimum Security Requirements for Federal Information and Information Systems. The following minimum security requirements are applicable to the Network Service and the Monitoring Service.

4.2.5.1 Technical Controls

4.2.5.1.1 Access Control

The Access Control technical controls are used to limit information system access to authorized users, processes acting on behalf of authorized users, or devices (including other information system) and to the types of transactions and functions that authorized users, processes, and devices are permitted to exercise. Access controls includes account management to assign authorizations.

1. The Network Service and the Monitoring Service must provide automated mechanisms to support account management in order to assign authorizations controlling access to the system.

The Network Service and the Monitoring Service must enforce assigned authorizations for controlling access to the system according to the transactions and functions allowed for authorized users, processes, or devices.

When encryption of stored information is employed as an access enforcement mechanism, the Network Service and the Monitoring Service must use cryptography that is FIPS 140-2, Level 1 or higher compliant.

The Network Service and the Monitoring Service must enforce assigned authorizations for controlling the flow of information within the system and between interconnected systems according to the types of information allowed for each system.

The Network Service and the Monitoring Service must enforce separation of duties through assigned access authorizations.

The Network Service and the Monitoring Service must be adaptable to enforce the most restrictive set of rights/privileges or access needed by users (or processes acting on behalf of users) for the performance of specified tasks.

The Network Service and the Monitoring Service must provide automated mechanisms to facilitate the review of user activities.

The Network Service and the Monitoring Service must provide automated mechanisms to facilitate the monitoring and control of remote access methods.

4.2.5.1.2 Audit & Accountability

The Audit & Accountability technical controls are used to create, protect, and retain information system audit records to the extent needed to enable monitoring, analysis, investigation, and reporting of unlawful, unauthorized, or inappropriate information system activity. The Audit & Accountability technical controls ensure that the actions of individual system users can be uniquely traced to those users.

1. The Network Service and the Monitoring Service must generate audit records for all system management and account management operations.

1. The Network Service and the Monitoring Service must generate audit records for all security-related events. Auditable events logging and monitoring in accordance with FAA ATO and NIST 800-53 security guidance and requirements.

1. The Network Service and the Monitoring Service must capture sufficient information in audit records to establish what events occurred, the sources of the events, and the outcomes of the events.

1. The Network Service and the Monitoring Service must provide the capability to include additional, more detailed information in audit records for audit events identified by type, location, or subject.

1. The Network Service and the Monitoring Service must provide a mechanism so that audit records may be backed up before their capacity is exceeded.

1. In the event of an audit processing failure or audit storage capacity being reached, the Network Service and the Monitoring Service must alert appropriate organizational officials.

1. In the event of an audit processing failure or audit storage capacity being reached, the Network Service and the Monitoring Service must be adapted to either overwrite the oldest audit record or stop generating audit records.

1. The Network Service and the Monitoring Service must provide audit reduction and report generation tools that support after-the-fact investigations of security incidents without altering original audit records.

1. The Network Service and the Monitoring Service must provide time stamps for use in audit record generation.

1. The Network Service and the Monitoring Service must protect audit information and audit tools from unauthorized access, modification, and deletion.

1. The Network Service and the Monitoring Service must retain information system audit records to the extent needed to enable the monitoring, analysis, investigation, and reporting of unlawful, unauthorized, or inappropriate information system activity. Determination of the extent needed is to be determined post-award co-operatively between the Network Service and Monitoring Service provider and the FAA.

1. The Network Service and the Monitoring Service must ensure that the actions of individual information system users can be uniquely traced to those users.

4.2.5.1.3 Identification & Authentication

The Identification & Authentication technical controls are used to identify information system users, processes acting on behalf of users, or devices, and to authenticate the identities of those users, processes, or devices as a prerequisite to allowing access to information systems. Since the DDLS Air-Ground Subnetwork does not involve interactive use of the system, users are limited to those performing system management operations.

1. The Network Service and the Monitoring Service must uniquely identify users (or processes acting on behalf of users)

am. The Network Service and the Monitoring Service must authenticate users (or processes acting on behalf of users).

an. The Network Service and the Monitoring Service must identify specific ATS-related devices before establishing an interfacility connection. This includes between the FAA and the DDLS and between DDLS facilities.

ao. The Network Service and the Monitoring Service must authenticate specific ATS-related devices before establishing an interfacility connection. This includes between the FAA and the DDLS facilities.

ap. For password-based authentication the Network Service and the Monitoring Service must protect passwords from unauthorized disclosure and modification.

aq. For password-based authentication the Network Service and the Monitoring Service must prohibit passwords from being displayed.

ar. For password-based authentication the Network Service and the Monitoring Service must enforce password minimum and maximum lifetime restrictions.

as. For password-based authentication the Network Service and the Monitoring Service must prohibit password reuse for a specified number of generations.

at. For authentication the Network Service and the Monitoring Service must validate certificates by constructing a certification path to an accepted trust anchor.

au. For authentication the Network Service and the Monitoring Service must establish user control of the corresponding private key.

av. For authentication the Network Service and the Monitoring Service must map the authenticated identity to the user account.

aw. For pre-shared key authentication, the Network Service and the Monitoring Service must support secure out-of-band key distribution.

ax. For pre-shared key authentication, the Network Service and the Monitoring Service must establish user control of the pre-shared key.

ay. For pre-shared key authentication, the Network Service and the Monitoring Service must map the authenticated identity to the user account.

az. The system must provide feedback that does not compromise the authentication mechanism to a user during an attempted authentication.

ba. For authentication to a cryptographic module, the system must employ authentication methods that meet the requirements of FIPS 140-2, Level 1 or higher.

4.2.5.1.4 System & Communications Protection

The System & Communications Protection technical controls are used to monitor, control, and protect communications at the external and key internal boundaries of the information system. The System & Communications technical controls consist of architectural designs, software development techniques, and systems engineering principles that promote effective information security within an information system.

1. The Network Service and the Monitoring Service must provide application partitioning that separates operational functionality from system management functionality.

The Network Service and the Monitoring Service must prevent unauthorized and unintended information transfer via shared system resources.

The system must protect against or limit the effects of denial of service attacks.

The Network Service and the Monitoring Service must monitor communications at the external boundaries of the system.

The Network Service and the Monitoring Service must control communications at the external boundaries of the information system.

The Network Service and the Monitoring Service must protect communications (both operational and administrative) from intentional and unintentional threats.

When cryptography is employed within the system, the Network Service and the Monitoring Service must perform all cryptographic operations (including key generation) using FIPS 140-2, Level 1 or higher validated cryptographic modules operating is approved modes of operation.

4.2.5.1.5 Connectivity to the NAS

The NAS Connectivity technical control is used to protect communications at the external service delivery point and the internal boundary to the NAS Wide Area Network. The security requirements for connectivity to the NAS are provided in FAA Order 1370.121, Wide Area Network Connectivity Security, and guidance is provided in the FTI Operational IP User Guide, Appendix H: External User Connection Information.

a. Connectivity to the NAS at the internal service delivery point must be established through the NAS Enterprise Security Gateway, using one the methods described in the FTI Operational IP User Guide.

4.2.5.2 Operational Controls

4.2.5.2.1 Physical & Environmental Protection

The Physical & Environmental Protection operational controls are used to: (i) limit physical access to information systems, equipment, and the respective operating environment to authorized individuals; (ii) protect the physical plant and support infrastructure for information systems; (iii) provide supporting utilities for information systems; (iv) protect information systems against environmental hazards; and (v) provide appropriate environmental controls in facilities containing information systems.

1. The Network Service and the Monitoring Service must protect information systems against environmental hazards.

1. The Network Service and the Monitoring Service must provide appropriate environmental controls in facilities containing information systems.

1. The Network Service and the Monitoring Service must control and restrict all physical access points to the facilities where information systems and network equipment reside, to authorized individuals.

1. The Network Service and the Monitoring Service must monitor physical access to the network equipment and information system to detect and respond to physical security incidents.

1. The Network Service and the Monitoring Service must protect power equipment and power cabling for the network equipment and information system from damage and destruction.

4.2.5.2.2 System & Information Integrity

The System & Information Integrity operational controls are used to: (i) identify, report, and correct information and information system flaws in a timely manner; (ii) provide protection from malicious code at appropriate locations within the information system; and (iii) monitor information system security alerts and advisories and take appropriate actions in response.

1. The Network Service and the Monitoring Service must identify known information and information system flaws that impact the operational status of the system.

The Network Service and the Monitoring Service must provide a mitigation plan to correct newly discovered information and information system flaws within 24 hours.

The Network Service and the Monitoring Service must correct the identified flaw within a maximum time allowed for restoral of the affected service upon identification of information or information system flaw.

The Network Service and the Monitoring Service must provide protection from malicious code including provisions for updates of attack definitions at appropriate locations within the information system.

The Network Service and the Monitoring Service must provide the capability to produce information system security alerts and advisories.

The Network Service and the Monitoring Service must provide automated tools to monitor events on the information system, detect attacks, and provide identification of unauthorized use of the system.

The Network Service and the Monitoring Service must provide automated mechanisms to support the incident handling process.

The Network Service and the Monitoring Service must provide automated tools to scan for vulnerabilities in the system including, as appropriate, Spam and Spyware detection.

The Network Service and the Monitoring Service must identify and handle error conditions without providing information that could be exploited by adversaries.

The Network Service and the Monitoring Service must employ automated system-wide intrusion detection tools.

The Network Service and the Monitoring Service must employ automated tools to support near-real-time analysis of events.

The Network Service and the Monitoring Service must provide mechanisms to prevent newly discovered information and information system flaws from spreading to other unaffected system components by isolating the affected system components and operating the service using the unaffected components of the system. (Note: Service might be affected or operate in a degraded manner when affected system components are isolated and are then subjected to corrective actions.)

5 NETWORK SERVICE REQUIREMENTS

5.1 Network Service Functional Requirements

The Data Communications System for the Communications Service Provider functional requirements are described in the following subsections.

5.1.1 Coverage

The volumes of airspace coverage are defined within the confines below.

5.1.1.1 Airport Surface

1. The Network Service must provide airport surface coverage at the airports identified in Appendix C, when ordered, including movement and non-movement areas. Non-movement areas include gate/ramp areas, de-icing locations and parking aprons.

5.1.1.2 En Route

1. The Network Service must provide en route coverage between 16,000 feet MSL and 60,000 feet MSL across the NAS within the Continental U.S. (CONUS).

The Network Service must provide air/ground communications coverage for all published Part 121 and 135 arrival and departure procedures within 5 NM around the Airport Reference Point (ARP), from airport surface areas to 2,500 feet AGL, over all airports with operational Data Comm Tower Service when the overlapping en route airspace is ordered.

bk. The Network Service must provide air/ground communications coverage for all published Part 121 and 135 arrival and departure procedures within 20 NM around the Airport Reference Point (ARP), from 2,500 feet AGL to 10,000 feet AGL, over all airports with operational Data Comm Tower Service when the overlapping en route airspace is ordered.

bl. The Network Service must provide air/ground communications coverage for all published Part 121 and 135 arrival and departure procedures within 40 NM around the Airport Reference Point (ARP), from 10,000 feet AGL to 12,000 feet AGL, over all airports with operational Data Comm Tower Service when the overlapping en route airspace is ordered.

bm. The Network Service must provide air/ground communications coverage for all published Part 121 and 135 arrival and departure procedures within 60 NM around the Airport Reference Point (ARP), from 12,000 feet AGL to 16,000 feet AGL or 16,000 feet MSL, whichever is higher, over all airports with operational Data Comm Tower Service when the overlapping en route airspace is ordered, except when TRACON service for the associated air traffic control tower is operational.

The Network Service must provide air/ground communications line-of-sight coverage to 115 NM off the coasts and land borders of the CONUS, or to the edge of the ARTCC boundaries, whichever is greater, at altitudes from 24,000 feet MSL to 60,000 feet MSL.

The Network Service must provide air/ground communications line-of-sight coverage to 75 NM off the coasts and land borders of the CONUS, or to the edge of the ARTCC boundaries, whichever is greater, at altitudes from 16,000 feet MSL to 24,000 feet MSL.

The Network Service must provide air/ground communications coverage for all areas defined in Appendix D. The specific airspace requirements in Appendix D are in addition to requirements 4.1.1.2a-g.

5.1.2 Routing and Forwarding

The following subsections provide requirements for data communications networking.

5.1.2.1 Application Integrity Maintenance

a. The Network Service must deliver the application layer integrity information (e.g., checksum) without modification.

5.1.2.2 Future Air Navigation Systems (FANS) Protocol Support

1. The Network Service must support A/G communications using the ACARS over AVLC (AoA) protocol as defined in ICAO Doc 9776, RTCA DO-224, ARINC Specification 631, ARINC Specification 618 and ARINC Specification 620. The AoA protocol uses the ACARS ARINC 618/620 specifications for the network and transport layers while using the VDL Mode 2 system for the link and physical layers.

1. The Network Service must accept ARINC Specification 620 formatted messages and reformat to ARINC Specification 618 and uplink to the appropriate destination.

bp. The Network Service must accept ARINC Specification 618 formatted downlink messages and reformat to ARINC Specification 620 and route to the appropriate ground end system.

bq. The Network Service must support FANS-1/A+ data messaging consistent with the FANS ATS INTEROP standard, DO-258A and ARINC Specification 622.

br. The Network Service must report on the failure of uplink transmissions in accordance with ARINC Specification 620.

bs. The Network Service must report on interception of downlink transmissions in accordance with ARINC Specification 620.

bt. The Network Service must properly process the ACARS message assurance text element identifier defined in ARINC Specification 620.

bu. If an aircraft degrades from VDL Mode 2 connectivity with the Network Service provider, the Network Service must accurately advertise VDL Mode 2 allowing the aircraft in question to return to VDL Mode 2 when it is reliably available.

bv. The Network Service must accept the Media Advisory messages, as defined in ARINC Specification 620, and update routing tables appropriately.

bw. The Network Service must discard the Media Advisory messages (i.e. not use for updating routing table) based upon a configurable parameter.

The Network Service must provide an alternate uplink retry capability on a per-aircraft configuration basis to resend failed uplinks.

The Network Service alternate uplink retry feature must support a configurable list of message assurance failure reason codes.

The Network Service must be configurable to not forward MAS failure messages to the the FAA automation platform when the message assurance failure reason codes are contained in a configurable list.

The Network Service must support the DB (Deliver by) Text Element Identifier (TEI) in the ARINC 620 message from ERAM.

5.1.3 Ground Radio

1. The ground radio portion of the Network Service must support the VDL Mode 2 protocol as defined in ICAO Annex 10 and ICAO Doc 9776, RTCA DO-224, and ARINC Specification 631.

1. The Network Service must provide at least 3 dB margin over the recommended operational coverage field strength in accordance with ICAO Annex 10, Vol III, Part 1, Section 6.2.2.

5.2 Network Service Performance Requirements

The performance requirements for the DDLS are provided via a collection of Quality of Service (QoS) profiles, uniquely identified by a combination of Latency, and RMA performance levels. Each profile consists of a selection of the required latency, availability, and integrity level.

5.2.1 Latency

The following subsections provide the requirements for data latency through the subnetwork portion of the DCS.

Latency in this section is referred as the one-way transfer delay from when a message is encoded for transmission until its successful arrival at its destination. It includes delay such as propagation delay and retransmissions, as well as subnetwork delays resulting from queuing/flow control, segmentation, processing, ground-network transmission, routing, etc. Delay is measured from last bit transmitted to last bit received on a data packet at the subnetwork level.

With respect to the subnetwork, the uplink transfer delay starts when the message is transmitted from the NAS Security Gateway interface and terminates when the message is sent from the VHF Digital Radio (VDR) to the CMU/Air Traffic Service Unit (ATSU) (or their equivalents). The time allocated to the Aircraft Radio reception and processing should be determined and subtracted from the overall measurement. With respect to the subnetwork, the downlink transfer delay starts when the message is received at the VDR interface from the CMU and terminates upon message reception at the NAS Enterprise Security Gateway. The time allocated to the aircraft data processing through the Aircraft Radio for downlink transmission should be determined and subtracted from the overall measurement. Alternate means of verification are permissible upon approval by the FAA.

5.2.1.1 LAT1 Performance Level

The following requirements define the LAT1 performance level. If the message never gets sent, it must count toward the latency performance measurement.

a. The Network Service uplink transfer delay for the LAT1 performance level must be less than or equal to 10 sec for 95% of all ATS data traffic. Measurement is performed over all ATS traffic within each VDL-2 frequency of operation within each ground station. In addition, measurement is performed at the Service Volume level for all ATS traffic regardless of the subnetwork.

b. The Network Service downlink transfer delay for the LAT1 performance level must be less than or equal to 10 sec for 95% of all ATS data traffic. Measurement is performed over all ATS traffic within each VDL-2 frequency of operation within each ground station. In addition, measurement is performed at the Service Volume level for all ATS traffic regardless of the subnetwork.

c. The Network Service uplink transfer delay for the LAT1 performance level must be less than or equal to 45 sec for 99% of all ATS data. Measurement is performed over all ATS traffic within each VDL-2 frequency of operation within each ground station. In addition, measurement is performed at the Service Volume level for all ATS traffic regardless of the subnetwork.

d. The Network Service downlink transfer delay for the LAT1 performance level must be less than or equal to 45 sec for 99% of all ATS data. Measurement is performed over all ATS traffic within each VDL-2 frequency of operation within each ground station. In addition, measurement is performed at the Service Volume level for all ATS traffic regardless of the subnetwork.

5.2.2 Data Integrity

The Packet Error Rate at the Network Service Delivery Point must be less than 1x10-5. The packet error rate is the number of incorrectly received data packets divided by the number of received packets. A packet is declared incorrectly received if at least one bit is erroneous or if it is delivered to an incorrect recipient. This metric excludes packets that were lost in transmission due to connection failure or excessive latency, as those are accounted by other metrics.

5.2.3 Undelivered Messages

The Contractor must ensure that less than 0.5% of all attempted controller-initiated uplinks do not result in a MAS Intercept 200 series code (not sent) within the specified latency in section 4.2.1.1.

5.2.4 Reliability, Maintainability and Availability

The Reliability, Maintainability and Availability performance requirements presented in this section apply to the VDL-2 subnetwork and should not take into account the availability of additional subnetworks in order to achieve the required performance levels.

5.2.4.1 Service Availability

A network service thread includes all equipment between the DDLS Service Delivery Point (SDP) and aircraft users, excluding any aircraft components. This would include the relevant emitting or receiving ground station antenna(s) as well as transmitting/receiving the necessary RF signal levels across the entire ordered service volume in question. Signal levels need to account for terrain impacts, as applicable to the service volume in question. For the purposes of availability, utilization of diverse ground station sites and other means of redundancy are included to provide the required level of availability for the ordered service volume.

a. The service availability for each network service thread must be at least 0.95 for the RMA0 performance level.

b. The service availability for each network service thread must be at least 0.9985 for the RMA1 performance level.

c. The service availability for each network…