The New Zealand Transport Accident Investigation Commission (TAIC) issued a report of the near grounding of the ferry ARATERE on September 29, 2004. The ferry was entering Tory Channel, a restricted waterway, when it failed to make a programmed course alteration while in automatic steering. The master intervened and made a manual alteration of course moments before the ferry would have grounded at
full speed. The cause of the problem has not been definitely determined, but it appears that the automatic navigation and track steering system probably defaulted to autopilot mode because it received an erroneous signal from an external input (possibly due to DGPS masking): the system received conflicting information and discarded the DGPS data: or the parameters of the off-track jump limit were exceeded. Subsequent to the incident, the harbormaster prohibited use of automated navigation systems in these restricted waters. The ferry company has instituted additional training procedures. Scary lesson learned: electronics are sometimes less reliable than humans. Report 04-214 (HK Law)