Incident Overview
Surviving passengers reported that during a flight from Stewart Island to Invercargill, symptoms of a right-hand engine failure occurred. The pilot corrected the issue by manipulating floor-mounted fuel tank selectors. Shortly afterward, both engines stopped. The pilot broadcast a Mayday and informed passengers that the aircraft would be ditched.
Ditching and Rescue
A successful ditching was carried out approximately 12 nautical miles south of Invercargill. All occupants escaped from the aircraft, but four persons exited without life jackets. The pilot entered the cabin but was unable to locate more life jackets before the aircraft sank. Rescuers reached the scene about an hour after the ditching and found that all those without life jackets had perished, as had a young boy who was wearing one.
Investigation Findings
A TAIC investigation found no evidence of any component malfunction that could cause a double engine failure, although due to seawater damage, the pre-impact condition of most fuel quantity system components could not be verified. Both fuel tank selectors were positioned to the left-hand tank, and it is probable that fuel starvation was the cause of the double engine failure.
Company procedures for the Cessna 402 lacked a fuel quantity monitoring system to supplement fuel gauge indications. Dipping of the tanks was not a feasible option. Company pilots believed that the aircraft was fitted with low-fuel quantity warning lights, which was not the case. As three pilots believed the gauges indicated sufficient fuel was on board before the preceding round trip to the island, exhaustion may have followed an undetermined fuel indicating system malfunction.
The failure of the company to require the use of operational flight logs, and other deficiencies in record keeping, were identified in the TAIC report. The much-publicised misunderstanding about the ditching location was not considered by the TAIC report to have affected the outcome of the rescue, but provides an example of the continued importance of using the phonetic alphabet in radiotelephony.
Safety Recommendation
A safety recommendation that operators use a fuel-quantity monitoring system to supplement fuel gauge indications was made by the TAIC report.