Mid-air collision between aero-tow aircraft and RC model at German airfield

Casualties unknown • Reinheim, DE

A Robin DR 400/180 R sustained significant damage to its tail section after colliding with a remote-controlled model aircraft near the Reinheim glider airfield.

What happened

On September 25, 2021, at approximately 15:25 local time, an Avions Pierre Robin DR 400/180 R departed from the Reinheim glider airfield performing an aero-tow operation with a DG-1000S glider. Shortly after takeoff, the pilot turned left to avoid flying over a nearby residential area. During the maneuver, the pilot noticed a remote-controlled model aircraft at the 1 o'clock position flying significantly lower than the tow aircraft. The pilot observed the model aircraft banking and descending, leading him to believe the threat had passed.

However, the model aircraft, which had been operating at a nearby model airfield, ascended and collided with the left horizontal stabilizer of the DR 400/180 R at an altitude of approximately 100 m AGL. The impact nearly severed the entire left side of the stabilizer. Despite the structural damage and a momentary disturbance in flight, the crew managed to maintain control and landed safely at the airfield. The model aircraft was destroyed upon impact.

The investigation

The BFU investigation examined the flight paths of both aircraft, witness statements, and the operational regulations of both the glider and model airfields. The investigation utilized data from the glider's collision warning system and analyzed the visual and acoustic limitations of the pilots involved. The BFU also reviewed the existing airspace permissions and the lack of coordination between the two adjacent flying sites.

Findings

Several factors contributed to the collision:

  • The remote pilot was intensely focused on controlling the model aircraft, which limited his ability to monitor the surrounding airspace.
  • The noise from the model aircraft's two-stroke engine likely masked the sound of the approaching tow aircraft.
  • The DR 400/180 R entered the model airfield's airspace at a low altitude.
  • The pilot of the tow aircraft was unaware of the existence of the nearby model airfield.
  • The pilot of the tow aircraft did not initiate an early avoidance maneuver after initially spotting the model aircraft.
  • The existing operational permits for the Reinheim glider airfield did not include specific provisions to mitigate the risk of conflict with the adjacent model airfield.

Safety action

In November 2023, the operators of both the glider airfield and the model airfield established an operational agreement intended to improve situational awareness for all users of the two sites.

Probable cause

The collision occurred because the tow aircraft entered the model airfield's airspace at a low altitude while the remote pilot's attention was focused on the model, combined with the tow pilot's failure to take early evasive action after first spotting the model aircraft.

Frequently asked questions

What happened in the 2021-09-25 Avions Pierre Robin DR 400/180 R accident near Reinheim, DE?

A Robin DR 400/180 R sustained significant damage to its tail section after colliding with a remote-controlled model aircraft near the Reinheim glider airfield.

What aircraft was involved and where did it happen?

The accident on 2021-09-25 involved a Avions Pierre Robin DR 400/180 R, at Reinheim, DE.

What was the probable cause of the accident?

The collision occurred because the tow aircraft entered the model airfield's airspace at a low altitude while the remote pilot's attention was focused on the model, combined with the tow pilot's failure to take early evasive action after first spotting the model aircraft.

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