Civil Aviation Authority of New Zealand
11 September 2006
MEDIA RELEASE
For further information contact:
Bill Sommer
Tel: 0-4-560
9411 or 0-27-546 8216
The accident report can be viewed on the CAA web site, www.caa.govt.nz, under Accidents & incidents - Fatal accident reports - 03/3794 ZK-UAC, 341 NM WSW of San Francisco
or use this link:
http://www.caa.govt.nz/Accident_Reports/ZK-UAC_Fatal_26Dec2003.pdf
Begins
Fatal Accident Report: ZK-UAC, 341 NM WSW of San Francisco, 26 December 2003
A Civil Aviation Authority safety investigation has concluded that a Pacific Aerospace Corporation 750XL, ZK-UAC, was ditched into the sea 341 nautical miles from San Francisco, after the pilot reported a problem with the aircraft fuel system. The aircraft was observed to nose over on to its back as it touched down on the sea. The pilot did not emerge from the aircraft after the ditching, and his body was later found by the emergency rescue team, submerged in the cockpit.
As the accident occurred in international waters, the CAA elected to investigate as the relevant agency of the State of Manufacture and the State of Registry of the aircraft. Assistance was sought from and provided by the National Transportation Safety Board and the Federal Aviation Administration (USA); and the Transportation Safety Board of Canada (the State of Manufacture of the engine) appointed an Accredited Representative.
The newly-completed Pacific Aerospace Corporation Ltd (PAC) 750XL was being ferried from Hamilton, New Zealand to Davis University Airport, California, via Pago Pago, American Samoa; Christmas Island, Kiribati; and Hilo, Hawaii. On the final leg, following a position report 858 nm from San Francisco, the pilot reported a problem with his fuel system, indicating a probable ditching.
While completing his checks after refuelling the aircraft prior to its departure from Hilo, the refueller noticed that fuel was running from the left leading-edge fuel tank cap. In reply to a comment by the refueller, the pilot said "It's okay, it will stop as soon as I taxi." The refueller expressed concern several more times before the aircraft departed, but was met by similar responses.
On most other types of aircraft, once the fuel level dropped away from the fuel tank cap and was no longer affected by aerodynamic suction, any leakage of fuel would have stopped. On the PAC 750XL, the fuel system design is such that the tanks in the front of the wing are continuously topped up. This meant that in flight the fuel loss continued until all fuel in the tanks in the rear of the wing and in the ferry system was consumed.
The safety investigation found that the quantity of fuel uplifted at Hilo indicated that the problem had existed on the previous leg between Christmas Island and Hilo, with a fuel loss rate of up to 125 litres (33.2 US gallons) per hour.
A comparison of the uplift figure at Hilo with the expected consumption on the previous leg should have provided sufficient warning to the pilot that a problem existed. In flight, the existence of the problem could have been detected by comparing fuel used by the engine with the fuel remaining in the tanks.
The aircraft departed Hilo some 22 minutes after last light, and it was not until almost eight hours later that the pilot indicated that he was having fuel difficulties. At that stage, the only course of action available to the pilot was to ditch the aircraft.
As far as can be established from air traffic service records, the aircraft was operated on all legs of the ferry flight at 14 000 feet pressure altitude without supplementary oxygen as required by CAR 91.209 and 91.533. While the range and severity of hypoxia symptoms will vary between individuals, it is recognised that at altitudes above 10,000 feet human performance does suffer measurably, and rules and regulations exist in aviation worldwide requiring the use of supplemental oxygen above that altitude.
The investigation concluded that cumulative fatigue, circadian rhythm and hypoxia were probably significant factors in the pilot's failure to detect the fuel problem in flight, in time to make a safe return.
The investigation also concluded that while the search and rescue facilities were activated appropriately, and had the potential to effect a successful rescue, the water entry impact on ditching was reasonably severe and probably incapacitated the pilot before he could vacate the cockpit.
As a consequence of the investigation, the CAA has amended the PAC 750XL flight manual to include warnings and descriptive material on the aircraft fuel system whereby the front tanks are continuously topped up while there is any fuel in the rear tanks; and the consequences of not ensuring the front tank caps are secure.