Accident Overview
On 21 September 2003 at 12:34 UTC, an ultralight Piper Cub 3, registration OK-DUO 04, crashed near Česká Lípa airport. The aircraft was destroyed. The pilot sustained serious injuries, and the passenger died. The accident was investigated by the Czech accident investigation body (ÚZPLN) in cooperation with the Police of the Czech Republic.
Flight Sequence
After a low pass over the airport, the aircraft entered a gentle climb. Approximately 500 meters from the threshold of runway 13, it struck tree tops and impacted the ground. Witnesses reported that after takeoff, the aircraft climbed to about 20 meters, then turned left and right, continuing at low altitude between airport buildings. It began a shallow climb at 90 km/h, but insufficient height gain led to the tree collision.
Injuries and Damage
The pilot suffered serious injuries. The passenger died. The aircraft was completely destroyed. No other damage was reported.
Aircraft Information
The aircraft was an amateur-built UL Piper Cub 3 (year of manufacture 1999), powered by a Micron engine (Walter, 1965) with a Křemen propeller (1999). The empty weight was 376 kg. The technical permit limited the aircraft to one crew member. At the time of the accident, the aircraft carried two persons (estimated 170 kg) and about 20 kg of fuel, resulting in a takeoff weight of approximately 566 kg—at least 116 kg (26%) over the maximum permitted takeoff weight. The aircraft's last inspection was valid until 30 September 2003.
Pilot Information
The pilot, aged 56, held a valid airline transport pilot license and an ultralight pilot license. He had about 8,000 hours on airplanes, but only 1 hour 50 minutes on ultralights. A medical examination was performed on 17 September 2003. A blood alcohol test after the accident revealed a level of 0.78 g/kg.
Meteorological Conditions
The weather at 12:30 UTC was partly cloudy, wind 130–150° at 2–3 m/s, visibility over 10 km, and temperature 30–32°C. The high temperature negatively affected climb performance.
Conclusions and Probable Cause
The investigation concluded that the main cause of the accident was the pilot's failure to maintain minimum flight altitude above surrounding obstacles. Contributing factors included piloting under the influence of alcohol, exceeding the maximum takeoff weight by at least 26%, and the relatively high air temperature. Additionally, the aircraft was operated with a passenger contrary to the technical permit.