200626 Incidents exposed while training

As a trainer, I often view unsafe practices which I would like to highlight to others through MARS. This includes the seductive effect of new tools like ECDIS and now AIS.

When we train masters on our training vessel, we have a radar and ECDIS side by side on a table on the front of the bridge for conning. The problem we find is that all our students favour the ECDIS almost exclusively over the radar, I think because it presents a 'prettier' and more easily understood picture. In consequence they miss moving targets at sea and also lose orientation with the radar picture. When we deliberately fail the GPS occasionally and thereby render the ECDIS non-operational, it throws the whole bridge team into confusion.

I guess this is a real danger with three separate sources of information, so all the more reason why at least AIS should be combined with the radar picture now.

I have recently been involved with VTS operations locally and a similar behavioural pattern has emerged. More than that, even the managers find it difficult to accept the idea that radar is more effective than AIS because it shows all targets, rather than those just fitted with AIS. We have been arguing with one group because they want to make AIS part of the essential equipment requirement and not radar.

Editor's note: It is essential that all mariners are not only trained in the operation of electronic navigation aids, but understand the weaknesses and how these aids should be used as a decision support system rather than a decisionmaking system. Mariners must be aware that no matter how impressive an electronic chart system may look, if it relies on only GPS input, it is still a single position fixing system and exclusive use of this violates the golden rule of navigation which has always been (and remains) never to rely on a single source of position fixing. A vessel's position as displayed on an ECS can and should be crossreferenced using radar, Loran, visual, depth sounder etc.

All trainers are encouraged to report incidents to MARS that can be brought to the attention of others for lessons to be learned.