What happened
On December 30, 2020, a Boeing 777, registration EC-MUA, was performing a flight from MUSC (Cuba) to Warsaw Chopin Airport (EPWA). As the aircraft approached the Warsaw TMA, a reorganization of the staffing at Warsaw Approach (APP) occurred. At 09:36 UTC, the Executive Controller (EC) took over the position and instructed the Planning Controller (PC) to leave the station and remain on standby. This action merged the two operational positions into a Single Person Operation (SPO) mode, which was a violation of established procedures for inactive APP EPWA operations.
While operating alone, the controller logged into the PEGASUS_21 system and subsequently left the operational station to conduct a mobile phone conversation. During this period, the controller remained approximately 10 meters away from the station near the Senior Controller position.
At 09:41 UTC, the Warsaw Area Control Center (ACC) instructed the crew of the Boeing 777 to establish contact with Warsaw Approach. The flight crew attempted to contact APP Warsaw multiple times between 09:41 and 09:43 UTC, but received no response. The crew was forced to revert to contact with Warsaw ACC. An ACC controller eventually went to the APP station and discovered the operational positions were unmanned. The controller finally responded to the aircraft at 09:43 UTC, and the approach proceeded without further incident.
The investigation
The PKBWL investigation examined the staffing changes at Warsaw Approach and the sequence of communications between the aircraft, ACC, and APP. The investigation focused on the controller's movement away from the station and the failure of the VCS system to alert the controller to the incoming radio calls due to the controller's physical distance from the console.
Findings
- The primary cause of the incident was the unjustified abandonment of the operational station by the sole controller working at the Approach control unit.
- A contributing factor was the decision to implement Single Person Operation (SPO) without properly staffing the secondary position, which violated the safety requirements outlined in the "INOP APP EPWA" procedures.