scope:

Introduction

This document contains Minimum Operational Performance Standards for airborne equipment to support Automatic Dependent Surveillance - Broadcast (ADS-B) utilizing the Universal Access Transceiver (UAT). ADS-B is a system by which aircraft and certain equipped surface vehicles can share position, velocity, in-situ weather, and other information with one another (and also with ground-based facilities/fixed locations such as air traffic services) via radio broadcast techniques. UAT is a multi-purpose aeronautical data link intended to support not only ADS-B, but also Flight Information Service - Broadcast (FIS-B), Traffic Information Service - Broadcast (TIS-B), ADS-B Rebroadcast (ADS-R), ADS-B Same Link Rebroadcast (ADS-SLR) and, potential future capabilities. While UAT has been expressly designed as a multi-purpose data link for surveillance-related applications, the focus of this document is on its support of ADS-B and basic ground uplink capabilities.

The standards contained in this document specify desired system characteristics that should prove useful to designers, manufacturers, installers and users of UAT equipment. Compliance with these standards is recommended as one means of ensuring that the equipment will satisfactorily perform its intended functions under conditions normally encountered in routine aeronautical operations. Some or all of these standards could be referenced by appropriate government agencies for certification and operational approval. Such regulatory application of any part of this document is solely the responsibility of appropriate government agencies. Version C of these MOPS (RTCA DO-282C) reflects additional operational experience with UAT, lessons learned in certification of UAT equipment, and further inputs from the International aviation community during the development of International Civil Aviation Organization (ICAO) Standards and Recommended Practices (SARPs) for UAT.

Note: The use of "shall" in the body of this document indicates a requirement. The use of "should" indicates a characteristic that is highly recommended but is not required.

Since the basic equipment implementation includes computer processing, RTCA DO-178(), Software Considerations in Airborne Systems and Equipment Certification, should be considered. Application of the software requirements of RTCA DO-178() should take into account the level of criticality of supported functions, consequences of equipment failure, and the presence and effectiveness of back-up and fault-monitoring features.

Section 1 of this document provides information and assumptions needed to understand the rationale for the equipment characteristics and requirements in this document. A high-level technical description of ADS-B and the UAT data link is provided, including the ability of UAT to support FIS-B, TIS-B, ADS-R/ADS-SLR, and independent ranging. This section forms the basis for the standards stated in Sections 2 through 4.

Section 2 contains the minimum operational performance standards for the equipment. These standards define required performance under standard operating conditions, as well as under stressed physical environmental conditions. Also included are bench test procedures to demonstrate equipment compliance with the stated minimum requirements.

Section 3 describes the performance required of installed equipment. Tests for the installed equipment are included when performance cannot be adequately determined through bench testing.

Section 4 describes the operational performance characteristics of the installed equipment, features, and controls.

Appendix A provides a Glossary and List of Acronyms.

Appendix B directs the reader interested in traceability to ATSSA MASPS, ASA MOPS and FIS-B MOPS to these respective documents.

Appendix C contains an Example ADS-B Message Coding for the UAT System.

Appendix D This appendix has been updated in version C of these MOPS with references describing the UAT Ground Infrastructure as implemented.

Appendix E provides information and guidance regarding Aircraft Antenna Characteristics.

Appendix F discusses Link Budgets and Scenario Dependent Ranges for the UAT System.

Appendix G describes the Standard Interference Environments that have been used to estimate UAT System performance. These environments are based upon internationally-developed traffic scenarios for high and low density airspace and near-worst-case estimates of interference caused by other systems transmitting on or near the UAT intended operational frequency of 978 MHz.

Appendix H discusses UAT Synchronization Issues.

Appendix I discusses UAT Timing Performance, an aspect of the UAT System that underpins, for example, potential use of UAT for supplementary ranging and positioning.

Appendix J provides a Reference Upper-Layer External Interface Format that can be provided by the UAT System for use by ADS-B Applications.

Appendix K details the UAT System Performance Simulation Results, which summarizes results of UAT System performance evaluations in the Standard Interference Environments of Appendix G. Air-to-air and air-ground system performance is assessed. Improved models based on measured operational data within updated performance results have been added in version C of these MOPS.

Appendix L Reserved.

Appendix M discusses UAT Error Detection and Correction Performance. The UAT link layer has been designed to improve UAT performance in high pulsed-interference environments as well as provide the underpinnings for any required future use of UAT for high integrity applications such as, for example, a cross-link for surveillance applications.

Appendix N provides a list of exemplary setup files for UAT equipment bench test procedures.

Appendix O provides a summary of testing and analyses that verify UAT compatibility with Distance Measuring Equipment (DME) and that DME equipment will operate without degradation in the presence of UAT and Joint Tactical Information Distribution System /Multi-functional Information Distribution System (JTIDS/MIDS, also referred to as Link 16) signals at the levels of the Standard Interference Environment defined in Appendix G.

Appendix P addresses issues pertaining to the statistics of overlapping ADS-B signals in a multi-user environment.

Appendix Q describes the manner in which GNSS position sources, which do not output velocity accuracy, can be characterized so that a velocity accuracy value associated with the position source can be input into ADS-B equipment as part of the installation process.

Appendix R provides guidance for decoding of information from messages transmitted by ADS-B Version One (1) or Two (2) Transmitting Subsystems when received by a ADS-B Version Three (3) Receiving Subsystem.

Appendix S Reserved.

Appendix T Reserved.

Appendix U provides a sample algorithm that meets the requirements for Vertical Status Determination in §2.2.4.5.2.5.1. This algorithm calculates the derived Vertical Status Determination (VSD) of the system. The reported VSD is determined as per the requirements in §2.2.4.5.2.5.3.1.

Appendix V contains validation test vectors for testing the VSD Algorithm.

Several different avionics architectures are possible for airborne UAT ADS-B equipment. The supporting hardware could exist as separate, stand-alone equipment; or it could be incorporated within other on-board equipment. As a result, equipment designers and manufacturers have considerable latitude in configuring UAT to support various ADS-B applications, as well as tailoring those configurations to various classes of users.

The word "equipment" as used in this document includes all components and units necessary for UAT to properly perform its ADS-B and Ground Uplink receipt functions. For example, the "equipment" for UAT may include a computer processor, transceiver with associated antenna, power supplies, and interfaces to other equipment. It should not be inferred from this example, however, that each UAT design will necessarily include all of the foregoing components. Nor should it be inferred that integration of other features or functions is not allowed. Considerable design flexibility is given to the manufacturer provided applicable requirements are satisfied.

Conceptually, ADS-B can support a wide range of users and applications. This document specifies both the minimum operational performance standards for UAT's basic ADS-B functions, as well as additional standards expected of advanced applications. Performance standards that apply to capabilities beyond the stated minimum requirements are identified as optional features, and provisions have been made in UAT Message formats to accommodate such features.