What happened
On 9 November 2015, two Cessna 172 S aircraft, registrations LY-BCF and D-EXAH, both operated by Aerojet Baltic, experienced a loss of separation in the vicinity of Valencia Airport, Spain. The aircraft were participating in a training flight from Requena aerodrome, practicing instrument approaches that involved a low approach to Valencia followed by a turn toward the SGO NDB.
During the sequence, the Valencia tower controller instructed the pilot of D-EXAH to interrupt the approach maneuver to avoid delaying a commercial air transport aircraft (ENT592) that was cleared to take off. This instruction was issued without coordination with the Valencia TACC controller. As the commercial aircraft departed, the separation between the two training aircraft decreased significantly. Eventually, the aircraft reached a minimum horizontal separation of 0.3 NM and a vertical separation of 500 ft, violating the required separation standards.
The investigation
The investigation examined the coordination between the Valencia tower (managed by FerroNATS) and the Valencia TACC (managed by ENAIRE). Investigators reviewed communications transcripts, radar tracks, and the Letter of Agreement (LoA) between the two air traffic service providers. The investigation focused on the transfer of flight information, the handling of the training flight sequence, and the impact of the commercial departure on the established traffic flow.
Findings
- The primary cause of the incident was that the Valencia tower controller cleared a commercial aircraft for takeoff and instructed D-EXAH to interrupt its approach without coordinating with the Valencia TACC or following the procedures established in the Letter of Agreement.
- The procedures specified in the Letter of Agreement between FerroNATS and ENAIRE were not observed.
- The transfer of the aircraft between control units was handled improperly; the transfer was conducted verbally without specifying the total number of school aircraft involved and without agreeing on the conditions for the turn to SGO NDB.
- The required horizontal separation between the aircraft was not maintained during the transfer.
- The tower controller lacked a flight progress strip and updated flight plan data for D-EXAH in the SACTA system.
- The Valencia TACC controller applied a reduced vertical separation of 500 ft as an emergency measure to prevent a collision, but did not notify the pilots of the loss of separation.