What happened
On November 16, 2020, a loss of separation occurred between two light aircraft operating at Madrid-Cuatro Vientos airport. The first aircraft, a Cessna 172-S, registration EC-NAQ, operated by Quality Fly S.A., was returning to the aerodrome after a flight training mission that had been diverted to Casarrubios due to earlier low visibility. The second aircraft, a Cessna 172-H, registration EC-DIC, operated by Aerofan, was performing takeoff and landing training on runway 09.
As the Cessna 172-S approached the aerodrome, the air traffic controller instructed the crew to join the traffic pattern for runway 09, specifically targeting the first third of the downwind leg. However, the crew of EC-NAQ failed to follow the instruction correctly. Instead of joining the established pattern, the aircraft entered the circuit in the opposite direction, flying through the tower area and establishing itself on a left-hand downwind leg for runway 27.
This maneuver caused the Cessna 172-S to cross the path of the Cessna 172-H at a vertical separation of approximately 50 to 70 feet. The pilot of EC-DIC reported seeing the other aircraft very close and below them. Both aircraft eventually landed safely without further incident, and there were no injuries and no damage to either aircraft.
The investigation
The CIAIAC investigation focused on the communications between the tower controller and the flight crews, as well as the operational procedures of the involved flight school. The investigation examined the controller's instructions, noting that while the controller used non-standard phraseology, this was not a direct cause of the separation loss.
Investigators also reviewed the actions of the Cessna 172-S crew, finding that they misidentified their preceding traffic. The crew believed they were following a large, distant aircraft approaching Madrid-Barajas, rather than the aircraft in the local circuit. Furthermore, the investigation noted that the Cessna 172-S was operating with its transponder in standby mode, which prevented the controller from identifying the aircraft on radar during the approach.
Findings
- The primary cause of the incident was a chain of errors by the crew of EC-NAQ, which led them to enter the traffic pattern in the wrong direction.
- The crew of EC-NAQ failed to fully comprehend the controller's instructions regarding the joining procedure.
- The crew of EC-NAQ incorrectly identified a distant aircraft as their preceding traffic, leading to a lack of situational awareness regarding the local circuit.
- The controller provided traffic information only to EC-NAQ and did not notify the aircraft in the pattern (EC-DIC) of the incoming traffic, contrary to established operating manuals.
- The crew of EC-DIC failed to maintain sufficient environmental scanning to detect the approaching aircraft before the crossing occurred.