TCAS Resolution Advisory averted mid-air collision near Dortmund

Casualties unknown • nahe Dortmund, DE

A TCAS RA prevented a near-miss between an Airbus A320 and a Cessna 525A during an instrument approach near Dortmund, Germany.

What happened

On April 27, 2011, at approximately 13:54 local time, a serious airborne conflict occurred near Dortmund, Germany, involving an Airbus A320-200 and a Cessna 525A. The A320 was operating an IFR flight from Kyiv, Ukraine, carrying 171 passengers and six crew members. The Cessna 525A was operating a VFR flight from Arnsberg/Menden to Westerland, carrying a pilot and one passenger.

As the A320 was descending toward the final approach fix for runway 24, the crew was in contact with Langen Radar. The controller provided traffic information regarding the Cessna, noting its position at the aircraft's eleven o'clock. Shortly thereafter, at 13:54:26, the A320 crew received a TCAS Resolution Advisory (RA) commanding a climb. Flight data recorder analysis confirmed that the TCAS RA was generated at 13:54:03 while the A320 was at 5,036 ft. In response to the RA, the A320 continued to descend to 4,956 ft before initiating a climb. The conflict was resolved, with the TCAS signaling "clear of conflict" at 13:54:32.

The closest proximity between the two aircraft was approximately 0.2 nautical miles horizontally and 400 ft vertically. While the A320 crew reported they had no visual contact with the Cessna, the pilot of the Cessna 525A reported seeing the A320 on his collision warning system and subsequently established visual contact at 13:54:22.

The investigation

The BFU examined radar records from the air traffic service provider and flight data recorder information from the A320. The investigation also reviewed radio communications and interviewed the pilots of both aircraft. Meteorological data from Dortmund airport confirmed visibility of 3 km with light drizzle and mist, with a cloud ceiling of 300 ft.

Findings

  • The A320 was operating under IFR in instrument meteorological conditions (IMC).
  • The Cessna 525A was operating under VFR in visual meteorological conditions (VMC), though the pilot noted flying through areas of poor visibility and light drizzle.
  • The pilot of the Cessna 525A attempted a heading correction to increase separation after detecting the A320 on his onboard collision warning system.
  • The TCAS Resolution Advisory (RA) on the A320 was the critical factor in preventing a collision.
  • There were no injuries or damage to the aircraft or third parties.

Probable cause

The near-collision was averted by the successful execution of a TCAS Resolution Advisory (climb) by the Airbus A320 crew, which corrected the vertical separation between the two aircraft.

Frequently asked questions

What happened in the 2011-04-27 1. Airbus Industries A320-200 accident near nahe Dortmund, DE?

A TCAS RA prevented a near-miss between an Airbus A320 and a Cessna 525A during an instrument approach near Dortmund, Germany.

What aircraft was involved and where did it happen?

The accident on 2011-04-27 involved a 1. Airbus Industries A320-200, at nahe Dortmund, DE.

What was the probable cause of the accident?

The near-collision was averted by the successful execution of a TCAS Resolution Advisory (climb) by the Airbus A320 crew, which corrected the vertical separation between the two aircraft.

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