What aircraft was involved and where did it happen?

The accident on 2021-04-18 involved a PIPER modelo PA-28R-200, registration EC-CST, at Término Municipal de Arroyomolinos (Madrid), ES.

What was the probable cause of the accident?

The incident was caused by the failure of the pilot of the Yakovlev Yak-52 to adhere to collision avoidance regulations and maintain separation from the Piper PA-28R-200, compounded by the use of an unauthorized and unregulated aerobatic area within the Madrid TMA.

Mid-air separation loss between two aircraft near Madrid

A near-collision occurred near Arroyomolinos, Spain, involving a Piper PA-28R-200 and a Yakovlev Yak-52 during local aerobatic maneuvers and a cross-country flight.

What happened

On April 18, 2021, at approximately 15:15 local time, a loss of separation occurred between two aircraft operating under Visual Flight Rules (VFR) within the Madrid Terminal Control Area (TMA).

The first aircraft, a PIPER PA-28R-200 with registration EC-CST, was performing a private cross-country flight from Badajoz-Talavera La Real to Madrid-Cuatro Vientos. While descending through 3,500 ft AMSL near the Xanadú shopping center, the crew observed another aircraft positioned slightly lower and to their right. The passenger noted a separation of approximately 6 meters between the two cockpits. The second aircraft then accelerated, passed in front of the EC-CST, and performed a sharp left bank and descent, exiting the crew's field of vision.

The second aircraft, a Yakovlev Yak-52 with registration EC-IAR, was conducting a local flight for the purpose of practicing aerobatic maneuvers near the Casarrubios del Monte aerodrome. The pilot reported that after completing a maneuver in a steep dive at approximately 260 km/h, the pilot encountered the other aircraft below their position. The pilot performed an evasive maneuver, passing behind and to the right of the EC-CST to regain separation.

The investigation

The CIAIAC investigation examined the flight paths, radar tracks, and the regulatory status of the airspace used for aerobatic maneuvers. The investigation focused on the separation between the two aircraft and the legitimacy of the "aerobatic box" (caja acrobática) located north of the Casarrubios del Monte aerodrome.

Investigators analyzed the aircraft's movements and found that while the exact minimum horizontal and vertical separation could not be precisely determined, the proximity was sufficient to compromise operational safety. The investigation also reviewed the aeronautical information publications (AIP) and the authorization status of the aerobatic area.

Findings

The primary cause of the incident was the failure of the pilot of the EC-IAR to maintain adequate separation from the other aircraft in accordance with collision avoidance rules.
The pilot of the EC-IAR was not rated for aerobatic flight.
The aerobatic box used by the EC-IAR lacked formal authorization from the competent authority.
There was a lack of clarity in aeronautical publications regarding the exact boundaries and physical properties of the aerobatic area.
The current configuration of the aerobatic area allows aircraft to penetrate the Madrid TMA, creating a potential safety deficiency for other operations within the controlled airspace.

Safety action

A recommendation was issued to the aerodrome operator to request the establishment of a formally recognized zone for safe aerobatic flight from the DGAC.
A recommendation was made to suspend aerobatic activities in the current "aerobatic box" until a safe, approved airspace structure is implemented.
A recommendation was issued to ENAIRE to correct discrepancies in the VFR Guide regarding the airspace boundaries of the aerobatic area.