ARINC 704A : 1999

1.0 Introduction and Description
1.1 Purpose of This Document
1.2 Summary of Operational Characteristics
1.3 System Description
1.4 Interchangeability
1.5 Reliability
1.6 Regulatory Approval
1.7 Testability and Maintainability
2.0 Interchangeability Standards
2.1 Introduction
2.2 Form Factors, Connectors, and Index Pin Coding
2.3 Standardized Signaling
2.4 Standard Interwiring
2.5 Power Circuitry
2.6 Weights
2.7 Thermal Interface and Design
2.8 Environmental Test Categories
2.9 Inertial Reference Unit Mounting
2.10 Airplane Dynamic Environment
2.11 Initialization Protocol and Heading Set
3.0 System Design Considerations
3.1 Introduction
3.2 General
3.3 Basic Modes of System Operation
3.4 Outputs
3.5 Integrity Monitoring and Self-Test
3.6 Inertial Reference System Accuracy
3.7 Initialization Protocol
3.8 Heading Set (Attitude Mode Only)
3.9 IRS Updating with GNSS Data
4.0 Standard Signal Characteristics
4.1 Introduction
4.2 General Accuracy and Operating Ranges
4.3 Data Signals
4.4 Control Signals
5.0 Control/Display Unit (CDU) Design
5.1 General
5.2 Form Factors and Connector
5.3 Cooling
5.4 Panel Illumination
5.5 Annunciator Dimming
5.6 Power Supply for CDU Operation
5.7 CDU Interface Summary
5.8 Liquid Spillage Protection
5.9 Display Test
6.0 Provisions for Automatic Test Equipment
6.1 General
6.2 Unit Identification
ATTACHMENTS
1. IRU Dimensions and Tolerances
2. IRU Mounting Tray
3. IRU Rear Connector
4. Standard Interwiring
5. IRU Connector Pin Use Reference
6. Control/Display Unit (CDU) Outline and Mounting
7. CDU Connector Pin Layout/Usage
8. CDU Annunciator Display Dimming
9. IRS Block Diagram
10. IRS/GNSS Typical Architecture
11. Navigational Mnemonics
12. Environmental Test Categories
13. IRS Digital Inputs/Outputs
14. Additional IRS Digital Inputs/Outputs when used with
    ARINC 743A GNSS
15. GNSS Time Mark
Appendices
A Non-Standard Applications

Gives the basic features for a 4 MCU Inertial Reference System (IRS), which consists of the necessary inertial measuring devices and associated electronics that are specifically designed for installation in commercial transport-type aircraft, that can be used in place of an in-service 10 MCU ARINC 704 Inertial Reference System. The aim of this document is to give general and specific design guidance for the development of an IRS for airline use. Describes the standards that are necessary and the desired operational capability of the system to ensure interchangeability.