Near-collision between training aircraft and helicopter at Bern Belp Airport

Casualties unknown • Bern Flughafen (LSZB), BE, CH

A night flight training session involving an AT-3 R100 and an EC120 B helicopter resulted in a dangerous airprox at Bern Belp Airport.

What happened

On the evening of 21 November 2016, a night flight training session was underway at Bern Belp Airport involving an AT-3 R100, registration HB-SRB. The flight was part of a student pilot's first solo night circuit training. Simultaneously, an EC120 B helicopter, registration HB-ZIE, was approaching the airport following an off-airport landing near Düdingen.

During the approach phase, the air traffic controller managed the two aircraft on the same runway axis. While the controller informed the crew of HB-SRB that they were following a helicopter, the pilot of the aeroplane turned into the final approach leg. Although the controller provided several updates regarding the helicopter's position, the pilot of HB-SRB reported visual contact with the helicopter's red beacon but was unable to identify the helicopter's fuselage due to the background of the runway approach lights.

As the aircraft converged, the flight instructor in the HB-SRB observed the proximity and instructed the pilot to perform a go-around. During this maneuver, the aeroplane passed over the helicopter, which was hover-taxiing near the runway, at a vertical distance of approximately 15 metres.

The investigation

The Swiss Transportation Safety Investigation Board (STSB) examined the radio communications, radar records, and GPS data from both aircraft. The investigation focused on the sequence of instructions provided by the air traffic controller and the pilot's ability to maintain separation during night operations. The investigation also looked at the clarity of the controller's instructions and the student pilot's situational awareness.

Findings

  • The air traffic controller's instructions were not always concise or provided using standard phraseology, which contributed to a lack of clarity regarding the required spacing.
  • The pilot of HB-SDB failed to maintain the instructed downwind leg, turning into the base leg despite instructions to maintain spacing.
  • Night visual limitations prevented the pilot of HB-SRB from accurately estimating the distance to the helicopter, as only the red beacon was visible against the bright approach lights.
  • The air traffic controller relied on the pilot's reported visual contact rather than intervening earlier with a definitive instruction to avoid the hazard.
  • The flight instructor's timely instruction to execute a go-around prevented a more serious collision.

Probable cause

The near-collision was caused by a combination of non-standard radio communications from air traffic control and the pilot's inability to accurately judge distance to the preceding helicopter due to the visual challenges of night flight and bright runway approach lights.

Frequently asked questions

What happened in the 2016-11-21 AERO AT SP. Z O.O. AT-3 R100 accident near Bern Flughafen (LSZB), BE, CH?

A night flight training session involving an AT-3 R100 and an EC120 B helicopter resulted in a dangerous airprox at Bern Belp Airport.

What aircraft was involved and where did it happen?

The accident on 2016-11-21 involved a AERO AT SP. Z O.O. AT-3 R100, registration HB-SRB, at Bern Flughafen (LSZB), BE, CH.

What was the probable cause of the accident?

The near-collision was caused by a combination of non-standard radio communications from air traffic control and the pilot's inability to accurately judge distance to the preceding helicopter due to the visual challenges of night flight and bright runway approach lights.

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