Japan Coast Guard Aircraft Sustains Damage During Porpoise Landing

Casualties unknown • Chitose Airfield, JP

A Textron Aviation 172S experienced a series of bounces during a landing examination at Chitose Airfield, resulting in significant airframe damage.

What happened

On August 21, 2018, a Textron Aviation 172S, registration JA395A, operated by the Japan Coast Guard, sustained substantial damage during a landing attempt at Chitose Airfield. The flight was part of a practical pilot competence examination for a rating change. The crew consisted of the captain (an examinee), an instructor, and an inspector.

During the approach to runway 18L, the aircraft passed over the threshold at approximately 72 knots. The initial touchdown occurred at 62 knots, which triggered a bounce. Attempting to maintain the landing attitude, the pilot continued the sequence, but the aircraft subsequently struck the nose gear during a second touchdown. This led to a "porpoise" effect, characterized by repeated, unstable bounces. While the crew initially believed the oscillations would settle, the third touchdown involved a severe pitch-down attitude and high vertical acceleration. The instructor eventually called for a go-around, but the impact had already caused structural damage.

The investigation

Investigators utilized Flight Data Monitoring (FDM) from the aircraft to reconstruct the flight path and pitch angles. The FDM recorded a significant increase in vertical acceleration and a loud impact sound during the third touchdown. The investigation also reviewed external footage from a vehicle parked at the apron, which confirmed the sequence of the bounces. Physical inspections of the aircraft revealed deformation to the outer skin of the forward fuselage, damage to the engine room stiffeners, and cracks in the left forward fuselage stringer.

Probable cause

The aircraft sustained damage because it entered a porpoise condition following an initial bounce, ultimately resulting in a severe nose gear impact during the third touchdown.

Frequently asked questions

What happened in the 2018-08-21 Textron Aviation 172S accident near Chitose Airfield, JP?

A Textron Aviation 172S experienced a series of bounces during a landing examination at Chitose Airfield, resulting in significant airframe damage.

What aircraft was involved and where did it happen?

The accident on 2018-08-21 involved a Textron Aviation 172S, registration JA395A, operated by Japan Coast Guard, at Chitose Airfield, JP.

What was the probable cause of the accident?

The aircraft sustained damage because it entered a porpoise condition following an initial bounce, ultimately resulting in a severe nose gear impact during the third touchdown.

Investigation report by the Japan Transport Safety Board (JTSB). Original record: https://jtsb.mlit.go.jp/eng-air_report/JA395A.pdf. This page is a structured re-presentation; facts and quotes are in the Japan Transport Safety Board (JTSB) - Ministry of Land, Infrastructure, Transport and Tourism.

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