What happened
On 22 April 2013, two separate flight operations were being conducted near Ireland West Airport (EIKN) to calibrate navigation aids. The first, a Diamond Twin Star DA42, registration G-COBS, was tasked with calibrating the VOR. Simultaneously, a Piper PA 31-350, registration G-FCSL, was performing an ILS calibration.
While the G-COBS was executing a VOR approach to runway 09, it performed a go-around and transitioned to an approach for runway 27. During this maneuver, the aircraft's Traffic Advisory System (TAS) issued a warning. The crew observed traffic on a 90-degree intercept from the left, which was at the same altitude. The lateral separation between the two aircraft dropped to 0.42 nautical miles with no vertical separation. To avoid a collision, the pilot of G-COBS initiated an immediate right turn and climb. Both aircraft eventually landed safely with no injuries and no damage to either aircraft.
The investigation
The AAIU investigation examined the coordination between the two calibration flights and the Air Traffic Control (ATC) at Ireland West Airport. It was established that the IAA Engineering Unit had arranged for the VOR calibration without notifying the airport's technical services or ATC. Conversely, the airport's technical services had arranged the ILS calibration without notifying ATC.
At the time of the incident, the airport was operating under procedural control as it lacked radar service. The investigation also reviewed the communications between the Air Movements Controller (AMC) and the flight crews, noting that while the controller attempted to sequence the aircraft, the lack of prior notification regarding the simultaneous calibration tasks contributed to the risk.
Findings
- There was a lack of coordination between the different entities conducting calibration tasks, as the VOR calibration was not communicated to the airport or ATC.
- The Air Traffic Controller instructed the G-FCSL to fly behind the G-COBS, but did not explicitly refer to the specific approach status of the G-CO45 at that moment.
- The simultaneous presence of two uncoordinated calibration flights in the same airspace created a high-risk environment.
- The pilot of G-COBS relied on the Traffic Advisory System to detect the conflicting aircraft during the approach.