This part of ISO 22090 specifies the construction, performance, and testing of a device employing only magnetic means as transmitting heading devices required by chapter V, SOLAS 1974 (as amended). A Transmitting Heading Device (THD) is an electronic device that provides information about the ship’s true heading. In addition to the general requirements contained in IMO Resolution A.694(17) to which IEC 60945 is associated and the relevant standard for the sensing part used, the THD equipment shall comply with the following minimum requirements. Where the IMO performance standards which apply to the sensing part do not specify a geographical operating area the THD shall operate a) at a minimum rate of turn 20 °/s and b) from 70° latitude south to 70° latitude north as a minimum. The THDs complying with the requirements contained in this part of ISO 22090 can be used for heading information as contained in chapter V of the SOLAS Convention. In addition such THDs are intended to meet the dynamic requirements contained in the HSC Code, chapter 13 for the carriage of a suitable device providing heading information. NOTE 1 Several technologies can be used to detect and transmit heading information. It is illogical to standardize the detection of the heading separately from the transmission of the heading. Therefore, separate parts of this part of ISO 22090 refer to different technologies. The requirements of this part of ISO 22090 only apply to the principle of the geomagnetic. Other technologies are covered in other parts of ISO 22090. NOTE 2 All requirements that are extracted from the recommendation of IMO Resolution MSC.116(73) on performance standards for transmitting heading devices are printed in italics. A standard magnetic compass with a pickup sensor could be applied as a sensing part of this standard of geomagnetic principle. However the IMO performance resolution MSC.116(73) requires that the THD is intended to be met for the dynamic requirements of the HSC code. Nevertheless, when the THD would be only used other than the HSC, the limit of rate of turn may be 6 °/s instead of 20 °/s. The main changes compared to the present edition are as follows; — Requirements related to bridge alert management (BAM) will be added to the clause of requirements and type test. — Delete previous Annex A and will define the alerts with a standard alert identifier in new Annex A. — The normative references and bibliography will be updated. — Editorial revision of the document in general according to the ISO/IEC Directives, Part 2. — Clause 3: Along with renewal of the overall structure of the document, the terms, definitions and abbreviated terms will be updated. — Clause 4: The IMO performance requirements that will define in each clauses at present edition will be summarized in Clause 4. — As new annex will be added as IEC 61162 interface overviews.