What aircraft was involved and where did it happen?

The accident on 2003-08-08 involved a 1. GEFA-Flug AS105 GD, at Rostock, DE.

What was the probable cause of the accident?

The collision was caused by the failure to maintain adequate separation between the two airships and the improper application of avoidance maneuvers, specifically a misjudged turn that resulted in intersecting flight paths.

Mid-air collision between two airships over Rostock

Two AS105 GD airships collided over the Warnow harbor area in Germany, resulting in significant damage to one vessel's envelope.

What happened

On August 8, 2003, two AS105 GD airships, the Thunder & Colt/AS 105 GD (registration not provided) and the GEFA-Flug/AS 105 GD (registration not provided), departed from an external launch site in Rostock-Gehlsdorf. The flights were conducted as part of a promotional mission for sponsors during a large maritime event.

At approximately 19:50, the two vessels were flying at altitudes between 30 and 40 meters above the water surface in the harbor area of the Unterwarnow. While the airships were approaching each other from opposite directions, the pilot of the Thunder & Colt/AS 105 GD initiated a turning maneuver. This maneuver caused the flight paths to intersect, leading to a collision where the passenger gondola of the Thunder & Colt/AS 105 GD struck the upper envelope of the GEFA-Flug/AS 105 GD at an angle of approximately 90 degrees.

The impact caused a 3.60-meter tear in the upper section of the GEFA-Flug/AS 105 GD envelope, which subsequently ruptured along a longitudinal seam for an additional 8.20 meters. The loss of lift caused the envelope to buckle and the vessel to descend close to the water's surface. To stabilize the damaged craft, the pilot utilized intensive burner use, effectively operating the airship like a hot air balloon to reach a safe landing area in Rostock's old town. There were no injuries resulting from the incident, though the GEFA-Flug/AS 105 GD sustained heavy damage.

The investigation

The BFU investigation utilized video footage of the approach to reconstruct the sequence of events. The investigation examined the flight profiles, the coordination of the flights, and the technical condition of both aircraft. It was noted that while a seaplane event was occurring nearby, the airship flights were coordinated by a local balloon company rather than the official flight controller of the seaplane event. The investigation also reviewed the flight experience of both pilots and the meteorological conditions at the time of the accident.

Findings

The pilots were flying at altitudes significantly below the minimum safety altitude.
The pilot of the Thunder & Colt/AS 105 GD misjudged the clearance during a turning maneuver, leading to the crossing of flight paths.
Failure to maintain sufficient separation and failure to apply standard collision avoidance rules were the primary factors.
The intense use of burners to recover the damaged vessel caused overheating and burning of the envelope material in certain areas.
Both pilots possessed the necessary licenses and sufficient flight experience on the specific type.