What happened
On 16 October 2017, two aircraft operated by Etihad Aviation Training experienced a serious loss of separation approximately three nautical miles north of Al Ain International Airport. The first aircraft, a Diamond DA42NG (registration A6-FTX), was performing a missed approach procedure. During its climb, the pilot received instructions from Approach East Radar Control to halt the ascent due to other traffic in the area. The instructor pilot subsequently disengaged the autopilot and began a descent to a new assigned altitude.
Simultually, an Embraer Phenom 100 (registration A6-EFA) was operating in the same airspace. As the DA42NG descended, the Traffic Collision Avoidance System (TCAS) on both aircraft triggered a Traffic Advisory (TA). The two aircraft came within close proximity, specifically 0.5 nautical miles laterally and 300 feet vertically, before the conflict was resolved.
The investigation
The UAE Air Accident Investigation Sector (AAIS) examined the sequence of events, focusing on the actions of the flight crews and the air traffic controller (ATCO) at Approach East Radar Control. The investigation reviewed radar snapshots, communication recordings, and flight data. Investigators looked into the handover procedures between night and morning shifts, the accuracy of flight strip information, and the coordination between the approach control and the aerodrome controller.
Findings
- The primary cause of the incident was the loss of minimum separation between the two aircraft while they were both adhering to instructions provided by air traffic control.
- The ATCO incorrectly perceived the E50P as operating under VFR (Visual Flight Rules) rather than IFR (Instrument Flight Rules), despite the flight strip correctly indicating IFR status.
- There was a lack of coordination between the approach controller and the aerodrome controller; specifically, the approach controller changed the aircraft's altitude on radar but failed to notify the aerodrome controller to issue a corresponding altitude restriction.
- The Letter of Agreement (LoA) between the two control units lacked clear instructions for managing IFR training flights and did not explicitly define responsibilities for standard missed approach instructions.
- The ATCO failed to report the incident to a supervisor or file an official incident report through the required safety systems.
Safety action
Following the investigation, several safety recommendations were issued to GAL Air Navigation Services and the GCAA. Key actions include:
- A requirement to review and correct the Letter of Agreement to ensure clear responsibilities for handling IFR, VFR instrument, and IFR training flights.
- The development of new training scenarios for air traffic controllers to improve human factors awareness, specifically regarding communication deficiencies during handovers and the importance of maintaining situational awareness.
- A mandate for the GCAA to review amended procedures to ensure alignment between different control units.