They Had Enough Fuel, But Could Not Get It To The Engines

The Twin Otter, N153QS, owned by Seafly LLC, a Delaware Corporation with a representative office in Palo Alto, CA, was involved in a fatal accident during a ferry flight to Hawaii. This aircraft, returning from an extended operating period in the Caribbean and Central America, was being flown by a U.S.-based contractor. The two pilots on board died, and our hearts go out to their families.

The incident occurred on the morning of Saturday May 21, 2023, when the aircraft, a Viking Air DHC-6-400 Twin Otter, departed from Santa Rosa, California for Hawaii. The aircraft was originally designed to fly approximately 700 nautical miles, had been retrofitted with an auxiliary fuel system to enable longer flights, according to the Federal Aviation Administration (FAA) records.

After takeoff and following approximately two hours of flight southwest toward Hawaii, the aircraft reversed its course around 10:40 a.m., as per Flightradar tracking data. The pilots reported to Air Traffic Control a malfunction with the fuel transfer system, leading to an inability to use the additional fuel that was on board. In response, the pilots changed course and flew back towards Half Moon Bay, California, a decision likely influenced by the lack of fuel supply due to the inability to transfer available fuel between tanks.

At 1:30 p.m., the U.S. Coast Guard received a distress call from the pilots. They reported their location at approximately 70 nautical miles west of Pacifica, California, and estimated that their remaining fuel would last no more than 15 minutes. The pilots informed the Coast Guard of their intent to ditch the aircraft into the ocean, and they also mentioned the presence of a yellow life raft onboard.

The Coast Guard responded by deploying an aerial search crew, which located the aircraft around 2:30 p.m., approximately 40 nautical miles southwest of San Francisco. The aircraft was observed to be upside down in the water, with no immediate sighting of the life raft. A rescue swimmer was able to observe and confirm that the two pilots were still strapped in the plane and unresponsive. The pilots were later pronounced dead at the scene, as reported by the National Transportation Safety Board (NTSB) spokesperson, Sarah Taylor Sulick.

The identities of the two pilots have yet to be released by the San Mateo County Sheriff’s Office. In the meantime, the NTSB investigators are endeavoring to recover the aircraft and ascertain the cause of the crash.

Accident Aircraft on Floats Shortly Before the Accident – question remains on if the floats were present or absent during the accident
Courtesy /u/spookystreet

The causal determination in aircraft accidents at sea can be challenging and usually involve many related and contributing factors, especially when aircraft are altered for extended operations over water that involve installing fuel tanks that are put in locations not originally designed for them. Fortunately, it appears that the wreckage from the California accident is recovered and will prove most beneficial in determining what went wrong.

While the cause of this most tragic accident is under investigation, it provides a poignant reminder of the risks inherent in aviation. It underscores the importance of stringent safety protocols regarding the maintenance and modification of aircraft and the continuous review and testing of all aspects of flight operations before the extended flights.

Aviation Law Group PS has extensive experience handling aircraft accidents at sea, including many seaplane accidents on the West Coast, in British Columbia, and in Alaska. We have handled many De Havilland (Viking Air) Otter accidents, and are currently working on two Otter accidents, one in Alaska and another Viking Air Otter seaplane accident that occurred in Washington. While the accident off California occurred in international waters, certain U.S.-based federal law will likely apply to civil claims against the responsible parties. ALG attorneys are all commercial pilots, and two are FAA-certified mechanics. Our attorneys are also licensed to practice law in California and Hawaii, and we associate with Canadian lawyers when needed, as Canada is where Viking Air, Ltd. and De Havilland Aircraft of Canada, Ltd. are located.  Thus, we are in a unique position to assist families in these types of accidents.