RTCA DO-368

Description / Abstract: Introduction

This document designated as RTCA/DO-XYZ contains Minimum Operational Performance Standards (MOPS) for airborne navigation equipment using the Global Orbiting Navigation Satellite System (GLONASS) and the Global Positioning System (GPS). The document provides standards for a combined GPS and GLONASS singlefrequency airborne supplemental navigation sensor equipment not augmented by groundor space-based systems. In this document, the terms "GPS/GLONASS equipment" or "GPS/GLONASS receiver" are used to refer to the combined GNSS airborne equipment capable of providing position information using signals from both GPS and GLONASS constellations.

Separate standards exist for GNSS using ground- or space-based augmentations. Additionally, separate documents will be created in the future to address standards for multi-constellation dual frequency (MC/DF) equipment.

The basis for this MOPS is RTCA/DO-316 (which was derived from RTCA/DO-229E class Beta 1 receiver MOPS without SBAS requirements). Therefore this MOPS makes extensive use of texts from and references to those documents, particularly to RTCA/DO- 316. In doing so, the following convention is chosen:

• when a requirement stated in DO-316 relates to GLONASS only (or both GLONASS and GPS) the complete wording of the requirement from DO-316 is reproduced;

• when a requirement relates to GPS only, the reference paragraph number in DO-316 is given (without reproduction of the referenced requirement from DO-316).

The above also applies to requirements for GPS/GLONASS antenna units that are introduced in this MOPS based on RTCA/DO-301 “Minimum Operational Performance Standards for Global Navigation Satellite System (GNSS) Airborne Active Antenna Equipment for the L1 Frequency Band.”

In this document:

• the term "shall" is used to indicate requirements. An approved design has to comply with every requirement, which can be assured by inspection, test, analysis, or demonstration. In order to facilitate references to specific requirements throughout the document, all "shall" requirements are designated with [GLG X] sequential numbering (to be inserted in the final version of the document).

• the term "must" is used to identify items that are important but are either duplicated somewhere else in the document as a "shall", or are considered to be outside the scope of this document.

• the term "should" is used to denote a recommendation that would improve the GPS/GLONASS equipment, but does not constitute a requirement.

The standards define minimum performance, functions and features for GPS/GLONASS sensors that provide position information to a multi-sensor system or separate navigation system. They also address Area Navigation (RNAV) equipment to be used for the en route, terminal, and Lateral Navigation (LNAV) phases of flight. These standards are based upon a nominal allocation of the aircraft-level requirements in RTCA/DO-236C, Minimum Aviation System Performance Standards: Required Navigation Performance for Area Navigation, accounting for the unique issues associated with GPS/GLONASS navigation service and minimizing the need for pilot training.

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, and will ensure a basic compatibility with the requirements defined in RTCA/DO-236C.

The regulatory application of these standards is the responsibility of appropriate government agencies.

The words "equipment" or "receiver", as used in this document, include components or units necessary (as determined by the equipment manufacturer or installer) to properly perform its intended function. For example, the airborne "equipment" may include: sensor(s), a computer unit, an input-output unit that interfaces with existing aircraft displays/systems, a control unit, a display, shock mount(s), etc. In the case of this example, all of the foregoing components or units constitute the "equipment". It should not be inferred from this example, however, that all GPS/GLONASS navigation equipment will necessarily include all of the foregoing components or units. The particular components of the GPS/GLONASS equipment will depend upon the design used by the equipment manufacturer, subject to the constraint that the equipment must meet the applicable requirements of this MOPS.

Furthermore, distinction should be made in interpreting the term “mode” which is being used in this MOPS with different meanings:

– navigation modes (e.g. “en route mode”, “terminal mode”); or

– GPS/GLONASS receiver operation modes (e.g. “GPS/GLONASS mode”, “GPS-only” mode, “GLONASS-only” mode); or

– fault modes in integrity analysis (e.g. “satellite failure mode”, “constellation fault mode”.

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 Section 2.

Section 2 contains the performance requirements. When measured values of equipment performance could be a function of the measurement method, this section also defines standard test conditions as well as testing methods. Section 2 contains the minimum performance standards for the equipment. These standards define required performance under standard operating conditions and stressed physical environmental conditions. It also details the recommended test procedures necessary to demonstrate compliance; provides references to guidance material for installed equipment performance and GPS/GLONASS equipment operational characteristics.

Note 1: The following structure of appendices include some appendices that are shown as “reserved for future use”; and, are interspersed among appendices that do contain information. This was done to maintain labeling commonality with RTCA/DO-316 to facilitate any future changes needed in both documents.