What happened
On September 21, 2003, at approximately 12:34 UTC, an amateur-built Piper Cub 3 (registration OK-DUO 04) crashed near the Česká Lípa airfield. The flight began following a short instructional period for a passenger. After taking off from runway 13, the aircraft climbed to an altitude of only approximately 20 meters.
During the flight, the pilot executed a left turn that transitioned into a right turn, directing the aircraft toward the airfield buildings. While flying at a speed of 90 km/h, the pilot attempted a shallow climb toward a wooded area at the edge of the airfield. Due to insufficient altitude, the aircraft's landing gear and wing struck the treetops, causing the aircraft to crash into a clearing. The impact destroyed the aircraft. The passenger sustained fatal injuries, while the pilot suffered serious injuries.
The investigation
The ÚZPLN investigation established several critical discrepancies between the pilot's account and eyewitness testimony. While the pilot claimed to have climbed to 150 meters, witnesses observed the aircraft maintaining a very low altitude of roughly 20 meters.
Investigators also performed a weight reconstruction of the wreckage. The empty weight of the aircraft was determined to be 376.2 kg. When accounting for the two occupants and fuel, the total takeoff weight exceeded the maximum allowable weight by at least 116 kg, representing an overload of at least 26%. Additionally, the investigation confirmed that the pilot's blood alcohol content was 0.78 g/kg.
Findings
- The failure to maintain minimum safe altitude over obstacles was the primary cause of the accident.
- The pilot was operating the aircraft under the influence of alcohol.
- The aircraft was significantly overloaded, exceeding its maximum takeoff weight by at least 26%.
- High ambient temperatures (30–32°C) negatively impacted the aircraft's climb performance.
- The presence of a passenger violated the aircraft's technical certificate, which was restricted to a single occupant.
- The pilot's maneuvering brought the aircraft to a stall speed while attempting to clear obstacles.