Near-collision involving Embraer 145 during approach to Norrköping

Casualties unknown • Serious incident – lack of separation between the aircraft G-RJXF, of the type Embraer 145, and SE-VKA, of the type Zephyr 2000C, south of Norrköping, SE

An Embraer 145 passenger flight experienced a sudden, uncommanded turn and descent toward an ultralight aircraft after intercepting a false ILS signal.

What happened

During a scheduled passenger flight arriving from Munich, an EMB-1EX (call sign Midland 753G) was performing an approach to Norrköping/Kungsängen Airport. The weather conditions were favorable, with visibility exceeding ten kilometers. As the crew was performing self-positioning for an ILS approach, the aircraft was flying above an ultralight aircraft operating in uncontrolled airspace.

Approximately seven nautical miles south of the outer marker beacon "ON", the aircraft suddenly executed a left turn toward the west. This maneuver took the plane outside the controlled airspace and caused it to descend toward the path of the ultralight aircraft, resulting in a near-collision.

The investigation

The investigation focused on why the aircraft deviated from its intended flight path. It was established that the aircraft's autopilot, which had been armed for the approach, intercepted a false ILS signal while the plane was outside the proper coverage area of the approach aid. This false signal commanded the aircraft to turn and descend.

Air traffic controllers were unable to intervene in time to correct the deviation. The initial turn was initially perceived by the controller as the crew making a visual correction toward the airport. The subsequent descent and turn caused confusion and communication disturbances, which prevented a timely corrective instruction from being issued. Furthermore, the investigation noted that according to the air traffic service provider's manual, the self-positioning phase for this ILS approach should have been terminated via radar vectors to reduce the risk of intercepting false signals.

Findings

  • The primary cause of the incident was inadequate planning and follow-up regarding the approach procedure.
  • A contributing factor was a lack of crew knowledge regarding the risks associated with false ILS signals.

Probable cause

The incident was caused by improper approach planning and monitoring, compounded by the aircraft's autopilot responding to a false ILS signal.

Frequently asked questions

What happened in the 2018-10-17 aircraft accident near Serious incident – lack of separation between the aircraft G-RJXF, of the type Embraer 145, and SE-VKA, of the type Zephyr 2000C, south of Norrköping, SE?

An Embraer 145 passenger flight experienced a sudden, uncommanded turn and descent toward an ultralight aircraft after intercepting a false ILS signal.

What aircraft was involved and where did it happen?

The accident on 2018-10-17 involved a aircraft, registration G-RJXF, at Serious incident – lack of separation between the aircraft G-RJXF, of the type Embraer 145, and SE-VKA, of the type Zephyr 2000C, south of Norrköping, SE.

What was the probable cause of the accident?

The incident was caused by improper approach planning and monitoring, compounded by the aircraft's autopilot responding to a false ILS signal.

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