A twin-engine turboprop that went down in the Pacific off Northern California on Saturday, May 20, 2023 killed both pilots aboard, and federal investigators homed in quickly on how a fuel system, not a fuel supply, may have doomed the flight. The aircraft, a Viking Air DHC-6-400 Twin Otter, went down around 2:15 p.m. in the water roughly 40 miles off Half Moon Bay, per a statement from the National Transportation Safety Board, and the crew of a Coast Guard response found the plane and “confirmed the pilot and copilot suffered fatal injuries.” They were the only people on board.
The flight’s audacity drew attention from the start. Per the FAA, the turboprop had departed Santa Rosa, the Sonoma County airfield north of San Francisco, bound for Honolulu, a Hawaii crossing aviation outlet Aero-News called a bold ask for a DHC-6, an aircraft Viking Air lists as a 19-seat utility plane. About 61 nautical miles out, the crew radioed Oakland’s Air Route Traffic Control Center with word of mechanical trouble and turned back east toward Half Moon Bay, making clear they did not expect to reach it. Oakland alerted the Coast Guard, whose helicopter sighted the Twin Otter floating half-submerged some 35 nautical miles west of the coastal city. A rescue swimmer found both occupants in the cockpit, neither responsive, and officials said the pilots’ bodies were not immediately removed.
The NTSB’s early theory is fuel starvation, which it distinguishes from fuel exhaustion: starvation means usable fuel fails to flow from tank to engine, while exhaustion means the supply is gone entirely. Spokesperson Sarah Taylor Sulick revealed the aircraft had been retrofitted with a supplemental system including ferry tanks for the long overwater leg. “At this time, investigators believe there was enough fuel, but the system wasn’t properly transferring the fuel from the added ferry tanks to the main tanks,” she said.
The agency contracted a salvage firm to raise the wreckage and set about assembling the routine record: the airframe’s maintenance history, the two pilots’ backgrounds and training, and satellite communications from the accident flight. A preliminary report was promised by early June, with the NTSB and the FAA sharing the investigation. For a type better known on skis, floats and short bush strips than on transocean crossings of this sort, the case turned on whether the added tanks that made the attempt possible were also what undid it.
Sources
- NTSB Investigating: Fuel Starvation Suspected in 20 May DHC-6 Accident | Aero-News Network
- 2 killed when plane headed for Hawaii crashes in Pacific Ocean off Northern California | AP News
