Incident Overview
On September 9, 2012, at approximately 17:08 local time, a Robin DR 400/180 R aircraft departed from the special landing site Backnang-Heiningen (EDSH) in Germany. The pilot was conducting a local sightseeing flight as part of an aviation event, carrying three passengers. Prior to this departure, seven other sightseeing flights had been completed by the same pilot, totaling two hours of flight time.
Accident Sequence
Witnesses and video footage recorded the takeoff roll on the grass runway aligned 110°. The aircraft lifted off with normal engine noise but immediately entered a continuous rolling motion to the right around its longitudinal axis. It reached an approximate bank angle of 90 degrees before impacting the ground beside the runway. A post-impact fire occurred, which was quickly extinguished by emergency services.
Casualties and Damage
The crash resulted in three fatalities and one serious injury. Two individuals were recovered dead at the scene, while two others were transported to a hospital; one of these survivors later died from their injuries. The aircraft was destroyed, with the right wing detached and significant portions of the fuselage and left wing burned. No third-party damage was reported.
Investigation Findings
The German Federal Aviation Office (BFU) investigated the incident under case number BFU 3X134-12. The pilot, a 67-year-old holder of a Private Pilot License (PPL(A)), had over 1,000 flight hours and 23 recent takeoffs on this specific model. Medical records indicated the pilot was on Marcumar medication, with details withheld from the aviation medical examiner.
The investigation focused on wake turbulence generated by an AN-2 aircraft that had taken off approximately 39 seconds prior to the DR 400. Calculations by the German Aerospace Center (DLR) demonstrated that under near-calm conditions, the AN-2's wake could generate a rolling moment exceeding the corrective capability of the DR 400's ailerons if the smaller aircraft entered the vortex core. Subsequent flight tests in 2014 using smoke visualization confirmed the DLR's theoretical models regarding the persistence and intensity of the AN-2's wake turbulence.