What happened
On July 27, 2006, a Piper PA-28RT-201T, registration EC-ENR, departed from San Sebastián Airport at 14:35 local time. The flight was operating under visual flight rules (VFR) with a single pilot on board, destined for Vilar da Luz Airport near Porto, Portugal.
While the initial portion of the flight proceeded normally, the weather conditions involved significant cloud cover, with ceilings between 2,000 and 3,000 ft and the potential for cumulonimbus formation. Upon reaching 6,000 ft, the aircraft's flight path began to deviate from the planned route, characterized by continuous heading changes. After maintaining 7,100 ft for approximately two minutes, the aircraft performed a sudden right turn, resulting in a rapid descent. The aircraft disappeared from radar screens at 6,300 ft and subsequently impacted the ground in a heavily forested area near Itziar, in the municipality of Deba. The impact was followed by a post-crash fire that destroyed the aircraft and caused local vegetation to burn.
The investigation
The investigation examined the aircraft's flight trajectory via radar data and communications with San Sebastián and Bilbao air traffic control. Investigators analyzed the wreckage, noting that the aircraft struck the ground in an inverted position at a nearly vertical angle. The investigation also included a detailed inspection of the Teledyne Continental TSIO-360-FB engine, which revealed no mechanical anomalies or malfunctions prior to the accident.
Physical evidence showed that the horizontal stabilizer had detached from the aircraft in flight. Investigators determined that the aircraft may have exceeded its maximum maneuvering speed (Vma) during the abrupt maneuvers, leading to excessive aerodynamic loads that caused the structural failure of the stabilizer and the detachment of other components.
Findings
- The primary cause of the accident was the loss of aircraft control due to probable spatial disorientation of the pilot.
- The pilot's flight pattern after 6,000 ft—characterized by erratic heading and altitude changes—suggested an attempt to navigate through gaps in the cloud layer, which likely exacerbated the disorientation.
- The aircraft suffered structural failure in flight, specifically the detachment of the horizontal stabilizer.
- The pilot was experienced, with approximately 1,600 total flight hours and 1,200 hours in this specific aircraft type.
- The aircraft was properly maintained and held a valid certificate of airworthiness.