INTRODUCTION

This document contains Minimum Operational Performance Standards (MOPS) for airborne equipment for Automatic Dependent Surveillance-Broadcast (ADS-B) and Traffic Information Service – Broadcast (TIS-B) utilizing 1090 MHz Mode S Extended Squitter (1090ES). The supporting hardware can be incorporated within other on-board equipment, or alternatively, the ADS-B equipment may be a separate avionics unit.

NOTE: Definitions of acronyms (e.g., MOPS, ADS-B, 1090ES) and of many other terms (e.g., “Extended Squitter”) can be found in Appendix B of these MOPS.

Compliance with these standards by manufacturers, installers and users is recommended as one means of assuring that the equipment will satisfactorily perform its intended functions under conditions encountered in routine aeronautical operations. The regulatory application of these standards is the responsibility of appropriate government agencies. For example, in the United States, the Federal Aviation Administration (FAA) publishes and maintains a Technical Standard Order (TSO-C166) for 1090ES ADS-B equipment to reference the requirements and bench test procedures in Section 2 of this document. In the European Union, the European Aviation Safety Agency (EASA) publishes and maintains a European Technical Standard Order (ETSO-C166) for 1090ES ADS-B equipment to the same reference in this document.

Since the equipment implementation includes a computer software package, the most recent version of the Software Considerations in Airborne Systems and Equipment Certification, (RTCA DO-178C/EUROCAE ED-12C) is applicable. When determining the level of software requirements, as defined in RTCA DO-178C/EUROCAE ED-12C, or subsequent versions, the equipment manufacturer should consider the criticality level appropriate for the installation certification, equipment failure analysis, and the fault monitoring being accomplished.

In addition, since the measured values of equipment performance characteristics may be a function of the measurement method, standard test conditions and methods of test are recommended in this document.

1090ES is documented and standardized internationally at ICAO. Relevant ICAO documents include Annex 10 Volume IV Standards and Recommended Practices (SARPs) as well as ICAO Document 9871 (Technical Provisions for Mode S Services and Extended Squitter).

Throughout this document, the term CAS is used to mean a generic collision avoidance system, applicable to any of the existing airborne collision avoidance implementations. Rarely, the terms TCAS (RTCA DO-185A/B / EUROCAE ED-143), ACAS Xa (RTCA DO-385 / EUROCAE ED-256), ACAS Xu (RTCA DO-386 / EUROCAE ED-275), or ACAS II (ICAO SARPs) are used when the associated text applies to a specific implementation. The full descriptor ACAS Xa/Xo is shortened to ACAS Xa, and TCAS II is shortened to TCAS. In this document, the term ACAS X is used when text applies equally to ACAS Xa and ACAS Xu. Original RF message names, e.g., TCAS Resolution Message, are retained.

Section 1 of this document provides information and assumptions needed to understand the rationale for equipment characteristics and requirements stated in the remaining sections. It describes typical equipment applications and operational goals and forms the basis for the standards stated in Sections 2 and 3.

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

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

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

Appendices A, E, G, J, N, and S are normative (i.e., they include requirements or direct guidance on requirements), whereas all other Appendices are informative (i.e., they do not include requirements). The following is a short description of each of the Appendices contained in this document:

Appendix A defines the formats and coding for 1090 MHz Extended Squitter ADS-B and TIS-B Messages, expanding upon the requirements of Section 2.2.

Appendix B contains a list of acronyms and definition of terms used in this document.

Appendix C contains validation test vectors for testing the Broadcast Message Format Algorithm

Appendix D provides references of specifications for ground architecture that can support surveillance for ATC using Extended Squitter ADS-B reports.

Appendix E provides guidance for establishing ADS-B Weather (ADS-B Wx) parameter values for ADS-B systems broadcasting Aircraft State, Weather State and Alternate Weather State Messages. Broadcast of these messages along with data contained in the Emergency/Priority Status Message comprises the ADS-B Weather Air Reports (ADS-B Wx AIREPs). ADS-B Wx AIREP parameters include aircraft and meteorological data primarily sourced through interfaces with external onboard systems. Certain ADS-B Wx AIREP parameters are specified for configuration during ADS-B system installation. Others are generally available onboard advanced aircraft from typical systems such as air data and/or flight management systems. A subset of the ADS-B Wx AIREP data must be sourced from dedicated sensing systems or derivation algorithms that are typically installed under supplemental type certificates. ADS-B Wx AIREPs support next generation ADS-B applications such as Flight-deck Interval Management (FIM), wake vortex separation and surfing applications, hazardous weather detection and avoidance, aviation weather forecasting, and air traffic management and control procedures.

Appendix F contains guidance in determining the ADS-B Position Reference Point, the nominal location of a transmitting ADS-B participant.

Appendix G provides a concept of operations (ConOps) and recommendations for reporting meteorological information based on pilot observations via ADS-B. Broadcast of Flight Weather Messages, Temp, Wind & Turbulence Messages, and Hazardous Weather Messages, which comprises ADS-B Weather Pilot Reports (ADS-B Wx PIREPs). Pilot Report messages, when sent, include data sourced from pilots through an appropriate avionics interface device. ADS-B Wx PIREPs support hazardous weather detection and avoidance, aviation weather forecasting, and air traffic management and control procedures.

Appendix H discusses ADS-B report assembly and provides additional guidance on the subject.

Appendix I identifies and discusses examples of the enhanced reception techniques for Extended Squitter that have been shown to meet the enhanced reception performance requirements.

Appendix J discusses determining the Navigation Accuracy Category for Velocity (NAC_V) and Geometric Vertical Rate Accuracy and describes the rationale for the values used in TABLE 2-18, “NAC_V Data.”

Appendix K Commitment to License (CtL) Phase Overlay Technology.

Appendix L discusses and provides a TABLE showing, by equipage class, the impact of radio frequency interference on Extended Squitter report integrity.

Appendix M provides a description of techniques for extending the effective air-to-air range of 1090 MHz ADS-B Subsystems, and discusses the transmission power for Class A3 airborne installations.

Appendix N defines the formats and coding for 1090 MHz Extended Squitter ADS-B Messages that are broadcast by ADS-B Version Zero (0), RTCA DO-260/EUROCAE ED-102 compliant 1090 MHz ADS-B Subsystems, ADS-B Version One (1), RTCA DO-260A compliant 1090 MHz ADS-B Subsystems, and ADS-B Version Two (2), RTCA DO-260B/EUROCAE ED-102A compliant 1090 MHz ADS-B Subsystems, and defines how the ADS-B Report Generation Function of Version Three (3) 1090 MHz ADS-B Receiving Subsystems is to utilize messages received from targets that are broadcasting with Version Zero (0), Version One (1), and Version Two (2) Message formats.

Appendix O provides a sample algorithm that meets the requirements for position message format determination in §2.2.3.2.2.1.3. This algorithm calculates the derived format of the system. The reported format is determined as per the requirements in §2.2.3.2.2.1.4.1.

Appendix P presents the results of modeling and simulations to estimate the air-to-air performance of 1090 MHz Extended Squitter.

Appendix Q reserved.

Appendix R provides a calculation of 1090 MHz Extended Squitter broadcast rates for different operational scenarios to show that transmission rates achieved over a 60 second period meet the required average rate over 60 seconds, and that there is no need to implement a function to limit the total number of 1090 MHz Extended Squitters transmitted over a certain period of time.

Appendix S specifies requirements for the Interrogation/Reply Monitor (IRM) application. IRM broadcasts two low-rate squitters. The IRM Interrogation Rate Monitor Message includes data concerning interrogation and suppression rates experienced by the transponder. The IRM Reply Rate Monitor Message includes data concerning current transponder reply rates. IRM is an optional capability and is not expected to be widely implemented.

Appendix T provides a tutorial and gives explanations and derivations of the Compact Position Reporting (CPR) equations given in Appendix A. CPR encoding and decoding can be implemented without using any of the information in this Appendix but, if a CPR implementation has problems, the information in this Appendix may be helpful in resolving the issue.

Appendix U provides detailed analysis of total and uncompensated latency in the broadcast horizontal position information. It provides unambiguous context for the timing requirements on the ADS-B Transmitting Subsystem, as well as recommendations for timing at the aircraft level.