What aircraft was involved and where did it happen?

The accident on 2019-07-16 involved a 1 Boeing 737-800, registration EC-LYR, at Espacio Aéreo LECS (Sevilla), ES.

What was the probable cause of the accident?

The primary cause was the premature transfer of the Ryanair aircraft to a new control sector, which, combined with a lack of coordination regarding a course change for the Air Europa aircraft, led to the loss of vertical and horizontal separation.

Loss of separation between two Boeing 737s near Écija

A mid-air loss of separation occurred between an Air Europa Boeing 737-800 and a Ryanair Boeing 737-8AS near Seville, Spain, due to air traffic control coordination failures.

What happened

On July 16, 2019, a loss of separation occurred between an Air Europa Boeing 737-800, registration EC-LYR, and a Ryanair Boeing 737-8AS, registration EI-FRP, approximately 15 km south of Écija, Seville. Both aircraft were in the approach phase of flight, descending toward Malaga and Seville airports, respectively.

Prior to the incident, a runway change at Malaga Airport necessitated a change in the arrival sequence for the Air Europa flight. The Seville Area Control Centre (LECSMA4) controller was managing both aircraft, maintaining vertical separation as they descended through different flight levels. However, the controller transferred control of the Air Europa aircraft to the Malaga approach sector (LEMGAPM) while the Ryanair aircraft was still under his responsibility.

Shortly after the transfer, the Malaga controller instructed the Air Europa aircraft to turn west to increase spacing from preceding traffic. This maneuver caused the trajectories of the two aircraft to converge. Although a conflict prediction alert (STCA-PAC) activated 29 seconds before the breach, the controllers of the different units failed to coordinate effectively. At 13:11:17 UTC, the aircraft reached a minimum distance of 1.3 NM horizontally and 0 ft vertically.

The investigation

The investigation examined the sequence of controller actions, the coordination between the Seville and Malaga approach sectors, and the impact of the existing Letter of Agreement (LoA) between the units. The investigation reviewed flight recorder data, radar data, and the functionality of the SACTA air traffic control system. It also assessed the impact of the runway incident at Malaga that had triggered the initial change in flight paths.

Findings

The loss of separation was caused by the early transfer of the RYR61NN aircraft from the LECSMA4 sector to the collateral sector before it was cleared for descent.
A contributing factor was the existing Letter of Agreement between the air traffic units, which permitted controllers to change an aircraft's course while it was still within the previous control area without prior coordination.
The Malaga approach controller's instruction to turn the Air Europa aircraft created the converging path.
The vertical separation was lost when the controller instructed the Ryanair aircraft to descend to a lower flight level than the Air Europa aircraft.
No TCAS TA or RA warnings were activated for either crew during the incident.

Safety action

REC 37/21: It is recommended that Enaire implements changes to ensure that LECS and LEMG APP controllers do not instruct aircraft to turn before they are in their area of responsibility unless prior coordination between the units has been established.