What happened
On July 1, 2014, an Embraer 170-200 was involved in an aviation incident at Milan Malpensa (MXP) airport. The flight was experiencing a departure delay due to a previously assigned takeoff slot. During the engine start and pushback procedures, the crew contacted the Delivery frequency (120.9) to announce they were "FULLY READY" for engine start and pushback.
Following this transmission, the crew was transferred to the Ground frequency. The crew believed they had received the necessary authorization to proceed with the pushback; however, they could not confirm with absolute certainty whether the clearance had actually been granted. As the pushback commenced, Air Traffic Control (ATC) contacted the aircraft on the Ground frequency, instructing the crew to stop the pushback and informing them that the movement had begun without prior authorization.
After clarifying the situation with controllers, the crew was permitted to continue the pushback and proceed with taxiing as normal. Upon returning to Warsaw (WAW), the crew filed an Air Safety Report (ASR) regarding the event.
The investigation
The investigation focused on the crew's communication with ATC and the psychological factors influencing their decision-making. Investigators conducted an interview with the commander to determine why the clearance was perceived as received. The investigation examined the impact of the departure slot pressure on the crew's performance.
Findings
- The primary cause of the incident was the inattentive monitoring of radio communications.
- The crew's mental state was heavily influenced by situational pressure caused by the departure delay and the need to meet the assigned takeoff slot.
- The crew's expectation of receiving a specific clearance led to a cognitive bias, where they interpreted the transition to the Ground frequency as an implicit authorization to proceed.