The Maritime Safety Committee has approved the ECDIS – Guidance for Good Practice, drawing together relevant guidance from seven previous ECDIS circulars into a single, consolidated document. 

The ECDIS – Guidance for Good Practice is important also to other ECDIS users besides of Navigators, like VTS and SAR operators/operation Centres, offshore installations etc.




ECDIS – Guidance for Good Practice, draws together relevant guidance from seven previous ECDIS circulars into a single, consolidated document.

It has been laid out in seven sections, namely:

  1. Chart carriage requirement of SOLAS
  2. Maintenance of ECDIS software
  3. Operating anomalies identified within ECDIS
  4. Differences between raster chart display system (RCDS) and ECDIS
  5. ECDIS training
  6. Transitioning from paper chart to ECDIS navigation
  7. Guidance on training and assessment in the operational use of ECDIS simulators


The guidance is intended to assist smooth implementation of ECDIS and safe and effective use on board ships. Ship operators, masters and deck officers on ECDIS-fitted ships are encouraged to use this guidance to improve their understanding and facilitate safe and effective use of ECDIS.

The guidance can also assist VTS and SAR operators in implementation as well as safe and effective use of ECDIS in VTS and SAR operations.



ECDIS units on board are required to comply with one of two performance standards (either IMO resolution A.817(19) or resolution MSC.232(82)), depending on the date of their installation. Essentially, where an ECDIS is being used to meet the chart carriage requirements of SOLAS, it must:

  1. be type-approved;
  2. use up to date electronic nautical charts (ENC);
  3. be maintained so as to be compatible with the latest applicable International Hydrographic Organization (IHO) standards; and
  4. have adequate, independent back-up arrangements in place.


ECDIS units on board ships must be type-approved. Type approval is the certification process that ECDIS equipment must undergo before it can be considered as complying with IMO performance standards


In accordance with SOLAS regulation V/, ships must carry all nautical charts necessary for the intended voyage. Ships required to fit ECDIS and ships choosing to use ECDIS to meet the chart carriage requirements of SOLAS should carry Electronic Navigational Charts (ENCs) or, where ENCs are not available at all or are not of an appropriate scale for the planning and display of the ship’s voyage plan, Raster Navigational Charts (RNC) and/or any needed paper charts should be carried.

IHO provides an online chart catalogue that details the coverage of ENCs. The IHO online chart catalogue can be accessed from the IHO website at:


As per SOLAS regulation V/27, all nautical charts necessary for the intended voyage shall be adequate and up to date. ECDIS software should be kept up to date such that it is capable of displaying up-to-date electronic charts correctly according to the latest version of IHO’s chart content and display standards. IMO performance standards for ECDIS specify the requirements for adequate independent back-up arrangements to ensure safe navigation in case of ECDIS failure. Such arrangements include:

  1. Facilities enabling a safe take-over of the ECDIS functions in order to ensure that an ECDIS failure does not result in a critical situation;
  2. A means to provide for safe navigation for the remaining part of the voyage in case of ECDIS failure. Normally, this means you either will have a back-up ECDIS or paper charts.



Any ECDIS which is not upgraded to be compatible with the latest version of the IHO ENC Product Specification or the Presentation Library may be unable to correctly display the latest charted features. Appropriate alarms and indications may not be activated even though the features have been included in the ENC, and any ECDIS which is not updated to be fully compliant with the latest version of the IHO Data Protection Standard may fail to decrypt or authenticate some ENCs, leading to failure to load or install. An up-to-date list of all the relevant IHO standards relating to ECDIS equipment can be accessed from the IHO website (



An ECDIS anomaly is an unexpected or unintended behaviour of an ECDIS unit which may affect the use of the equipment or navigational decisions made by the user. Examples include, but are not limited to:

  • failure to display a navigational feature correctly, such as:
  • navigation areas recently recognized by IMO such as PSSA and ASL
  • navigational lights with complex characteristics; and
  • underwater features and isolated dangers;
  • failure to detect objects by “route checking” in voyage planning mode;
  • failure to alarm correctly; and
  • failure to manage a number of alarms correctly.

Appropriate checks should be made with the equipment manufacturer. This is of particular importance where ECDIS is the only source of chart information available.

IHO has produced an ECDIS Data Presentation and Performance Check (DPPC) dataset that allows mariners/operators to check some important aspects of the operation of their ECDIS. This dataset contains two fictitious ENC cells which deck officers can load into their ECDIS units to assess operating performance and to determine whether there is any display anomalies that need to be remedied or managed in the way that the ECDIS is operated. The check dataset and accompanying instructions can be obtained from ENC service providers, or can be downloaded from the IHO website at:

It is important that any anomalies identified by mariners are reported to and investigated by the authorities to ensure their resolution. Therefore, Administrations or designated bodies are invited to:

  1. encourage vessels under their flag to report anomalies, with details on the ECDIS equipment and ENCs, to allow analysis;
  2. treat the identity of the reporter as confidential;
  3. agree to share information with other IMO Member Governments and international organizations on request; and
  4. issue alerts to mariners where such anomalies might affect safety of navigation.



ECDIS may be operated in one of the two modes:

  1. the ECDIS mode when ENCs are used; and
  2. the RCDS mode when ENCs are not available and RNCs are used instead.

ENC coverage has increased rapidly lately, but there could be areas for which suitably detailed ENCs may not have been issued, and RCDS need to be used. The RCDS mode does not have the full functionality of ECDIS and can only be used together with an appropriate portfolio of up-to-date paper charts.

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