National foreword

This British Standard is the UK implementation of ISO 22090‑2:2026. It supersedes BS ISO 22090‑2:2014, which is withdrawn.

The UK participation in its preparation was entrusted to Technical Committee EPL/80, Maritime navigation and radiocommunication equipment and systems.

A list of organizations represented on this committee can be obtained on request to its committee manager.

Contractual and legal considerations

This publication has been prepared in good faith, however no representation, warranty, assurance or undertaking (express or implied) is or will be made, and no responsibility or liability is or will be accepted by BSI in relation to the adequacy, accuracy, completeness or reasonableness of this publication. All and any such responsibility and liability is expressly disclaimed to the full extent permitted by the law.

This publication is provided as is, and is to be used at the recipient’s own risk.

The recipient is advised to consider seeking professional guidance with respect to its use of this publication.

This publication is not intended to constitute a contract. Users are responsible for its correct application.

Compliance with a British Standard cannot confer immunity from legal obligations.

This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 November 2026.

Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types of ISO document should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).

ISO draws attention to the possibility that the implementation of this document may involve the use of (a) patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a) patent(s) which may be required to implement this document. However, implementers are cautioned that this may not represent the latest information, which may be obtained from the patent database available at www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.

Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISO's adherence to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.

This document was prepared by Technical Committee ISO/TC 8, Ships and marine technology, Subcommittee SC 6, Navigation and ship operations.

This third edition cancels and replaces the second edition (ISO 22090‑2:2014), which has been technically revised.

The main changes are as follows:

to align with the latest gyro-related standards, the scope has been reduced and other applicable conditions have been moved to "Application" (5.1).
along with renewal of the overall structure of the document, the terms and definitions (Clause 3) have been updated;
Clause 4 (abbreviated terms) has been added;
IMO performance requirements have been summarized in Clause 5;
in 5.6, requirements related to bridge alert management have been added;
in 5.7.6, requirements related to electromagnetic compatibility have been added;
in 6.11, a test method for requirements related to bridge alert management has been added;
in 6.14, an electromagnetic compatibility test has been added;
Annex A has been replaced with a new Annex on alerts definition, including alert identifiers;
in Annex B, an IEC 61162 series interfaces overview has been added.
the normative references and bibliography have been updated.

A list of all parts in the ISO 22090 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A complete listing of these bodies can be found at www.iso.org/members.html.

Introduction

This document is aligned with IMO Resolution MSC.116(73) on performance standards for marine transmitting heading devices (THDs).

Any text in this document which is a citation from the IMO Resolution MSC.116(73), appears in italics. Within these citations, any changes to the original wording of the IMO Resolution MSC.116(73) are written in upright font.

In this document, the following verbal forms are used:

“shall” indicates a requirement;
“should” indicates a recommendation;
“may” indicates a permission;
“can” indicates a possibility or a capability.

1 Scope

This document specifies general requirements, construction, performance and testing methods of transmitting heading devices (THDs) using geomagnetic principles, which are required to comply with the International Convention for the Safety of Life at Sea (SOLAS) 1974 (as amended),^[3^] Chapter V, and IMO Resolution MSC.116(73).

This document is intended to be used in conjunction with IMO Resolution A.694(17) and with IEC 60945.

2 Normative references

3 Terms and definitions

4 Abbreviated terms

5 Performance and requirements

5.1 Application

5.2 Functionality

5.3 Information

5.4 Accuracy

5.5 Interface

5.6 Alert management

5.7 Other requirements

6 Type tests

6.1 General

6.2 Transmission error test

6.3 Static error test

6.4 Dynamic error test

6.5 Follow-up error test

6.6 Settling time test

6.7 Tests for correcting the magnetic heading by magnetic variations

6.8 Tests for adjusting magnetic deviations

6.9 Tests for the means of adjusting the deviation by vertical soft iron

6.10 Interface test

6.11 Alert management test

6.12 Fore-and-aft mark test

6.13 Non-magnetic housing test

6.14 Electromagnetic compatibility test

6.15 General requirement test

7 Marking and identification

Bibliography