What happened
On September 7, 2013, a Microbel TD 1+1 ultralight weight-shift control aircraft (DPM) was conducting a local flight near the Isières airfield (EBIS) in Belgium. The aircraft, equipped with a La Mouette Oryx wing, was carrying a pilot and one passenger. During the approach to the airfield, the aircraft was observed by a witness performing a right-hand turn and entering a steep dive. The aircraft struck the ground approximately 600 meters from the airfield, resulting in two fatalities. The impact was violent, with the aircraft traveling at approximately 91 km/ .
The investigation
The investigation by AAIU(Be) focused on the aircraft's configuration and the pilot's flight patterns. Investigators discovered that the aircraft's original type authorization had been invalidated by the installation of a different wing type without the necessary approval from the Belgian Civil Aviation Authority (BCAA). Furthermore, the wing itself had undergone unapproved structural modifications, including the removal of transversal rods. The investigation also examined the connection between the mast and the wing keel, which was found to be moving longitudinally and was only loosely secured by a makeshift rope.
Regarding flight operations, the investigation found that the pilot frequently deviated from the standard airfield circuit pattern at EBIS, opting instead to descend via steep, 360-degree turns from higher altitudes. Additionally, discrepancies were noted in the pilot's logbooks, with several recent flights not being recorded.
Findings
- The aircraft was not airworthy because the installation of the new wing type was not approved by the BCAA.
- The wing had been modified by removing transversal rods, a change not authorized by the manufacturer.
- The connection between the mast and the keel beam was unstable due to a makeshift rope.
- The pilot had limited experience with this specific wing and trike configuration.
- The loss of control was triggered by a steep descent maneuver that likely caused unexpected aircraft behavior due to the unapproved modifications.
- The pilot's habitual non-compliance with the airfield's landing circuit was not reported to the authorities, which prevented regulatory intervention.