Safety action taken: The Australian Hydrographic Office (AHO) has undertaken work to remediate the existing ENC portfolio by setting up a dedicated project team to encode obstruction area features at the same location as underwater rock and obstruction point features. An initial search revealed approximately 2,200 such features affecting about 243 ENCs. The project commenced in December 2018 and involved creating an obstruction area the same size as the isolated danger symbol, while also retaining the latter. This means that within the ECDIS, the symbol behaves electronically in the same way as it looks visually. The project was completed in March 2019 and the issue was raised with the IHO.
In addition, the AHO has advised the ATSB that they have published a supplement to the Seafarers Handbook for Australian Waters (AHP 20) to address a number of misconceptions amongst mariners regarding the accuracy of bathymetry within Electronic Navigational Charts (ENCs) and the impact that accuracy should have upon route planning and conduct. The supplement also addresses the dangerous effects of over-scaled ECDIS displays near features such as isolated danger symbols (Appendix F). The content of this supplement will be fully incorporated as a new chapter into the new edition of the handbook (Edition 5), due for publication in 2019. The content has also been offered to the IHO for publication as an IHO standard.