History of the Flight
The Aircraft, a privately owned Cessna 172RG registered JA3857, departed Iwami Airport for a familiarization flight to Kagoshima Airport. The return flight encountered reduced visibility near Mt. Aso, prompting the captain to deviate and climb. During descent for landing at Kagoshima Airport, the captain initially extended the landing gear to increase descent rate, then retracted it to increase airspeed for an earlier landing. He planned to extend the gear on downwind but entered the base-leg directly due to a runway change and concern about other traffic, forgetting the gear was retracted. The captain used a checklist but missed the gear-down item. The aircraft touched down with the gear retracted, resulting in a belly-landing.
Damage to Aircraft
The Aircraft sustained substantial damage, including scratch marks on the lower fuselage and deformation and damage to the propeller.
Captain Information
The captain, aged 48, held a private pilot certificate and a valid Class 2 aviation medical certificate. His total flight time was 378 hours 37 minutes, with 260 hours 46 minutes on the accident aircraft type.
Aircraft Information
The Cessna 172RG (serial number 172RG0123) was manufactured in 1979. Its weight and center of gravity were within limits at the time of the accident. The gear extension and retraction system functioned normally. However, the gear warning system did not sound when the throttle was at idle with the gear retracted. Investigation revealed that one of two screws securing the throttle switch was missing, causing the ground wire to disconnect.
Gear Warning System
The gear warning is designed to sound if the gear is not extended when the throttle is at idle (manifold pressure about 12 inHg or less) or flaps are extended beyond 20°. During on-ground testing, the warning did not sound at idle with the gear retracted, but it sounded when flaps were set to 30°. The warning worked when the disconnected ground wire was reconnected. No item to check the gear warning is included in the aircraft's flight manual. Maintenance records showed the gear warning was adjusted on February 3, 2015, but not checked during subsequent periodic inspections.
Meteorological Information
At 17:00, the wind at Kagoshima Airport was 230° at 8 knots, visibility 20 km, with few cumulus clouds at 4,000 ft and broken clouds at unknown altitude.
Additional Information
A video recording from the aircraft showed the shadow of the aircraft immediately before landing, confirming the landing gear was not extended.