What happened
On September 4, 2019, at approximately 18:12 LMT, a police Mi-8 helicopter was performing a training flight at Warsaw Babice airport. The crew was executing a circuit pattern with the intention of landing with one engine feathered. While positioned downwind for runway 28, the crew notified Babice Radio of their intention to land with one engine inoperative.
Simultaneously, a private Robinson R44 approached the ZULU waypoint and requested landing conditions. The air traffic controller instructed the R44 pilot to report position after the fourth turn. During the sequence, the crew of the Mi-8 informed the controller that they would be following the R44. The pilot of the R44 then identified the helicopter as being at position number two in the sequence.
As the Mi-8 was between the third and fourth turns, the crew began the procedure to feather an engine. Just before executing the fourth turn at an altitude of 1,400 ft, the crew received a TCAS alert indicating traffic at "0 miles." Upon checking, the crew observed the R44 approximately 200 ft below them, crossing their flight path from left to right while approaching a hangar on the north side of runway 28. The Mi-8 subsequently completed its landing safely on the south side of the runway.
The investigation
The PKBWL examined the radio communications between the crews and the controller, as well as the flight paths of both aircraft. The investigation reviewed the sequence of the circuit pattern maneuvers and the adherence to separation procedures. The commission also noted that the incident was referred to the Polish Air Force Flight Safety Inspectorate, which ultimately declined to classify the event as an aviation occurrence under its specific criteria.
Findings
- The air traffic controller at Babice Radio failed to react to the developing situation during the fourth turn of the circuit patterns.
- Both crews failed to maintain the required separation distances mandated by established circuit pattern procedures.
- Radio communications between the flight crews and the controller were handled incorrectly.
- The primary cause of the incident was the failure to maintain separation required during circuit pattern operations.