Incident Overview
On Saturday, October 7, 2023, at approximately 14:10 Japan Standard Time, a Christen Industries A-1 aircraft, registration JA4083, experienced a serious incident during landing at Hida Airpark (Operation Site) in Takayama City, Gifu Prefecture. The right wing tip came into contact with the runway surface during the ground roll after touchdown. The aircraft subsequently nosed over, causing the propeller and spinner to contact the runway. The aircraft sustained slight damage, and the pilot did not sustain any injury.
Aircraft and Pilot Information
The aircraft was a single-engine tailwheel-type airplane, serial number 1065, manufactured on November 29, 1988. It had a valid airworthiness certificate (No. Tou-2022-315) through November 16, 2023. The pilot, aged 71, held a private pilot certificate (airplane) issued on April 22, 1983, with a rating for single-engine (land) and a valid Class 2 aviation medical certificate through April 11, 2024. The pilot's total flight time was 734 hours 52 minutes, with 664 hours 14 minutes on the type and 40 minutes in the last 30 days.
Meteorological Conditions
Before landing, the pilot observed the windsock from the air and judged the wind to be from the north or north-northwest at about 5 m/s (approximately 10 kt). According to the glider club's Piste (training command post), the wind was from the north at 7 to 8 kt. However, wind records from the anemometer near the administration office indicated the wind at 14:10 was from the north at 8 m/s (about 16 kt). The flight manual specified a demonstrated crosswind velocity of 15 MPH (about 6.7 m/s, 13 kt).
Sequence of Events
The aircraft had taken off from the Operation Site to tow a glider and returned after releasing the glider. The pilot decided to land on Runway 10 following a preceding aircraft. The approach was made with flaps at 30° and a speed of about 60 MPH (52 kt). After touchdown, the pilot kept the elevators fully up with the control stick aft, ailerons neutral, and engine at idle without braking. The aircraft began veering left during the roll. The pilot applied right rudder to correct, but as speed decreased, directional control became insufficient. The aircraft veered sharply left, rolled to the right, and the right wing tip contacted the runway. It then nosed over, with the propeller and spinner striking the runway before coming to a stop.
Investigation Findings
No failures were found in the brake or flight control systems, and no cracks or unevenness were observed on the runway surface. The Piste did not provide wind information during the landing because conditions had not changed since the previous flight. The pilot did not request updated wind information via radio.
Probable Cause
The Japan Transport Safety Board determined that the probable cause of the serious incident was that, due to deceleration during the landing roll, it became difficult to control the aircraft's direction into the crosswind. The aircraft yawed due to the weathervane effect, leading to a ground loop that caused it to veer sharply left. Centrifugal force and the crosswind then rolled the aircraft to the right, likely causing the right wing tip to contact the runway surface. As the aircraft slowed almost to a stop, the horizontal tail floated due to the crosswind, lifting the aft fuselage and resulting in the nose over.