Landing and Overrun
During an instrument landing system (ILS) approach to runway 35, the approach was normal until the aircraft reached approximately 100 feet above the decision height. At that point, condensation was present on the windshield. The touchdown was hard. A witness reported that the aircraft touched down approximately one-third of the way down the 5,200-foot runway.
After landing, the propellers were in the ground fine setting. Braking action was ineffective on the wet runway, as the aircraft was not equipped with an anti-skid braking system. Subsequently, the aircraft continued off the runway, went down an embankment, and came to rest in a field. Scrub marks on the runway and reverted rubber on the tires indicated that the aircraft was hydroplaning.
According to the flight manual, 4,500 feet of runway (plus a 10% factor for the lack of anti-skid) would have been required to stop on a dry runway under the prevailing weather conditions, which included a slight tailwind. Two passengers acting as flight attendants assisted the other passengers in evacuating the aircraft.
Investigation Findings
An investigation revealed that the flight attendants were not properly trained, the passengers were not completely briefed before the flight, and the passenger briefing cards were inadequate. The aircraft was operating on a business flight to transport an entertainment troupe.
The investigation identified multiple factors across three occurrences:
Occurrence #1: Overrun (Phase: Landing - Roll) Findings included: weather conditions (tailwind, fog, rain); a dirty windshield; the pilot in command exceeded the proper touchdown point; the pilot in command experienced a visual/aural perception issue; the pilot in command made improper in-flight planning/decision; the pilot in command did not perform a missed approach; the runway surface was wet; and hydroplaning occurred due to water on the runway.
Occurrence #2: On Ground/Water Encounter with Terrain/Water (Phase: Landing - Roll) Findings included: the terrain was rough/uneven and downhill.
Occurrence #3: Miscellaneous/Other (Phase: Other) Findings included: the passenger briefing by the flight attendant was inadequate; the flight attendant had inadequate training in emergency procedures; and the company/operator management provided unclear information.
Probable Cause
The probable cause, as stated in the official findings, is that the overrun resulted from the pilot in command exceeding the proper touchdown point, improper in-flight planning/decision, and failure to perform a missed approach. These were compounded by tailwind, fog, rain, a dirty windshield, a wet runway, and hydroplaning. The subsequent ground encounter was attributed to rough/downhill terrain, and the inadequate passenger briefing and flight attendant training were noted as contributing factors.