Fatal Ultralight Crash During Glider Towing Near Bad Berka

Casualties unknown • nahe Flugplatz Bad Berka, DE

A Wild Thing WT01 ultralight aircraft crashed and destroyed itself after the towed glider entered an uncontrolled flight attitude, resulting in the death of the pilot.

What happened

On June 7, 2008, at approximately 13:57, a Wild Thing WT01 ultralight aircraft departed from the Bad Berka airfield performing a glider tow operation. The tow formation consisted of the ultralight and a SZD-9 Bocian glider. During the climb, the glider began to oscillate both laterally and vertically. The student pilot in the glider reported being caught in the propeller wash of the tug, necessitating several corrective interventions by the flight instructor.

As the oscillations increased in magnitude, the glider began to drift out of the required flight envelope. Witnesses on the ground observed the glider deviating from its path at low altitude. Shortly thereafter, the ultralight aircraft pitched forward, striking a metal staircase on a sewage treatment plant structure. The impact destroyed the aircraft and caused the death of the pilot. The glider successfully released the tow cable at an altitude of approximately 130 meters and returned to the airfield.

The investigation

The BFU investigation focused on the flight dynamics of the tow, the equipment used, and the pilot's recent training history. Investigators examined the tow cable, finding that instead of the required 300 daN breaking strength mechanism, a knot had been used as a substitute. The investigation also reviewed the flight logs of both the ultralight pilot and the flight instructor, noting significant gaps in recent towing experience. Additionally, the technical specifications of the tow cable length and the connection hardware were analyzed against the manufacturer's and regulatory requirements.

Findings

  • The primary cause of the accident was that the towed glider overtook the tug aircraft, leading to an uncontrolled flight attitude.
  • The accident was exacerbated by the use of a tow cable that was too short (approximately 30 meters, whereas the manual requires 40 to 60 meters).
  • The tow formation failed to separate in a timely manner; the ultralight entered an unrecoverable attitude at a low altitude before release could occur.
  • The tow cable was equipped with an improper ring pair that did not meet regulatory or manual specifications.
  • The ultralight pilot had not performed a glider tow in the 24 months preceding the accident.
  • It is possible that the pilot's lack of recent training contributed to a delayed reaction, or that the non-compliant hardware caused a malfunction during the release attempt.

Probable cause

The accident was caused by the glider overtaking the tug aircraft, resulting in an uncontrolled flight state that the ultralight could not recover from at such a low altitude. Contributing factors included the use of an undersized tow cable and the failure to execute a timely separation of the aircraft.

Frequently asked questions

What happened in the 2008-06-07 ULBI GmbH Wild Thing WT01 accident near nahe Flugplatz Bad Berka, DE?

A Wild Thing WT01 ultralight aircraft crashed and destroyed itself after the towed glider entered an uncontrolled flight attitude, resulting in the death of the pilot.

What aircraft was involved and where did it happen?

The accident on 2008-06-07 involved a ULBI GmbH Wild Thing WT01, at nahe Flugplatz Bad Berka, DE.

What was the probable cause of the accident?

The accident was caused by the glider overtaking the tug aircraft, resulting in an uncontrolled flight state that the ultralight could not recover from at such a low altitude. Contributing factors included the use of an undersized tow cable and the failure to execute a timely separation of the aircraft.

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