Fatal Stall During Low-Altitude Maneuver Involving Ka-4 'Šumák'

What happened

On August 3, 2004, a Ka-4 "Šumák" ultralight aircraft, registration OK-AUO 03, was conducting recreational flights near the village of Velké Petrovice. After completing several initial flights, the pilot took off for a third flight with a passenger on board. The aircraft flew over the village of Police nad Metují before returning toward the takeoff area to meet other spectators.

While performing a right-hand turn over a group of onlookers, the aircraft entered a steep bank. During the second stage of the maneuver, the aircraft reached a critical state, resulting in a stall and a subsequent impact with the ground. The impact caused the total destruction of the aircraft, with the cockpit area heavily deformed and the right wing torn from its main mount.

The investigation

The ÚZPLN investigation examined the aircraft's technical condition, the pilot's qualifications, the meteorological conditions, and the flight parameters. The investigation established that the pilot held a valid instructor rating and medical certificate. The aircraft was equipped with a Rotax 582 engine and a three-blade propeller.

Investigators analyzed the wreckage and ground impact marks, which indicated the right wing struck the ground first during a sharp right bank. Data from a Garmin GPSMAP 196 unit confirmed the flight history leading up to the accident. The investigation also noted that the takeoff area used near Velké Petrovice had not been formally verified for ultralight operations.

Findings

• The pilot's flight technique during low-altitude maneuvers was improper.
• The aircraft's maximum takeoff weight was exceeded by 41 kg.
• During the steep right turn, the aircraft exceeded the stall speed threshold for that specific flight configuration.
• Due to the low altitude, the pilot was unable to recover from the resulting wing drop and subsequent stall.
• The technical condition of the aircraft and engine was functional and did not contribute to the accident.
• Meteorological conditions were suitable for flight and were not a contributing factor.