Incident Overview
On August 27, 2017, at approximately 17:05 Japan Standard Time, a Robinson R44 helicopter, registration JA7981, experienced a low fuel situation while flying at an altitude of about 5,300 ft over an area 28 km northeast of Otsu City, Shiga Prefecture. The pilot executed an emergency landing at a school ground in Fushimi Ward, Kyoto City. No injuries or damage to the aircraft were reported.
Flight History
The helicopter, operated by Takumi Enterprise Helicopter & Airplane Co., Ltd., had departed from JPD Kyoto temporary helipad at 08:12 on August 26, 2017, with approximately 135 liters of fuel. It landed at Oyabe temporary helipad in Toyama Prefecture at 09:36 for an event. Over the next two days, the aircraft performed several flights, including parachute support and demonstration flights. On August 26, after moving to Uchiondo temporary helipad for refueling, the "LOW FUEL" warning light illuminated briefly before landing. A refueler supplied 100 liters of fuel, but the pilot did not visually inspect the fuel level or check the caps. On August 27, the helicopter flew again without refueling.
Preflight and Fuel Calculation
Before departing from Oyabe Helipad at 16:04, the pilot prepared a flight plan to JPD Kyoto, calculating a minimum required fuel of 110 liters based on a distance of 120 nm and an estimated flight time of 1 hour 50 minutes. During preflight checks, the pilot checked the fuel gauge and believed the quantity was sufficient. He did not accurately read the gauge.
In-Flight Events
While flying over the north end of Lake Biwa, the pilot noticed higher than normal fuel consumption. He considered diverting to Fukui Airport but decided to continue to JPD Kyoto as it was 10 nm closer. At around 17:00, the LOW FUEL warning light began to flash intermittently, becoming steady at 17:05. The GPS indicated an estimated arrival time of 17:18. According to the flight manual, the helicopter had about 10 minutes of fuel remaining after the warning light illuminated, leaving a deficit of approximately 3 minutes to reach the destination. The pilot informed JPD Kyoto of his intention to make a precautionary landing, selected a suitable site, and landed at 17:16. After cooling the engine, a mechanic refueled the helicopter with about 58 liters. The aircraft departed the next morning at 06:11 and landed at JPD Kyoto at 06:17.
Aircraft and Pilot Information
The helicopter, a Robinson R44 with serial number 1011, was manufactured on March 1, 2001. Its total flight time was 1,402 hours and 24 minutes. The pilot, aged 33, held a commercial pilot certificate for rotorcraft and had a total flight time of 682 hours and 34 minutes, with 355 hours and 46 minutes on the same type.
Fuel System Details
The main fuel tank capacity was 112.0 liters, and the auxiliary tank capacity was 64.0 liters. The LOW FUEL warning light activates when approximately 11.3 liters remain, providing about 10 minutes of flight at cruise power. The flight manual cautions against relying solely on this light for fuel management.
Meteorological Conditions
Aeronautical weather observations at nearby Fukui Airport at 16:00 reported wind from 350° at 9 kt, visibility 10 km or more, cloudy conditions with a cloud base at 5,000 ft. Wind profiler data along the route showed varying winds, including a headwind component that may have increased fuel consumption.