Incident Summary
A landing roll resulted in a runway excursion after the pilot manually deactivated the anti-skid system. The aircraft sustained substantial damage during the overrun. The event occurred on runway 05.
Sequence of Events
The pilot had computed landing performance data for a wet runway with anti-skid engaged, indicating sufficient runway length. The touchdown was reported as normal. During the braking phase, the aircraft began to fishtail. The pilot interpreted this as a failure of the anti-skid system and subsequently turned it off. The rollout continued with normal braking. The aircraft departed the end of runway 05.
Investigation Findings
Examination of the aircraft revealed no mechanical malfunctions or discrepancies. Performance analysis showed that more runway distance would have been required for a safe landing on a wet runway without anti-skid assistance. The braking sequence described by the pilot was consistent with dynamic hydroplaning, where braking effectiveness is completely lost, rather than an anti-skid malfunction.
Probable Cause
The pilot's premature decision to turn off the anti-skid during landing roll. Factors to this accident were hydroplaning conditions.