What happened
On December 11, 2022, an Airbus A3ly (registration HA-LVO) was taxiing on taxiway L toward the threshold of runway 29 at Warsaw Chopin Airport (EPWA) for departure. At the time, the airport was experiencing unfavorable weather conditions, including light snowfall and visibility reduced to approximately 1,500–1,800 meters.
Earlier in the sequence, the Tower Controller had cleared another aircraft to cross runway 29 from taxiway A4. Following this movement, the Tower Controller's Assistant was approached by the Airport Duty Officer, who requested permission to cross runway 29 from taxiway A4. Without consulting the Tower Controller, the Assistant granted the vehicle permission to proceed behind the previously cleared aircraft.
At 11:36:45 a.m., the Tower Controller, unaware that the duty vehicle had been authorized to enter the runway, issued takeoff clearance to the Airbus A321. At the moment the clearance was given, the duty vehicle was already entering the intersection of taxiway A4 and runway 29. The Controller only became aware of the vehicle's presence after hearing the takeoff clearance issued and was subsequently notified by the Assistant that the vehicle was crossing the runway. The flight crew of the Airbus A321 proceeded with the takeoff roll only after the duty vehicle had successfully cleared the runway.
The investigation
The PKBWL investigation examined the communications between the Tower Controller, the Assistant, and the Duty Officer, as well as the Surface Movement Radar (SMR) displays. The investigation established that the Assistant observed the movement of the first aircraft but failed to monitor the subsequent movement of the Airbus A321 due to increased airfield traffic and limited visibility. The investigation also reviewed the regulatory requirements for coordinating runway crossings with the Tower Controller.