What happened
On February 28, 2002, at 08:36 UTC, a BE 400A, registration OY-SIS, was holding at the CATIII point on runway 36R at Milan Linate Airport, awaiting takeoff. The aircraft was part of a departure sequence, positioned sixth in line. While the pilot was instructed to "Hold short 36," the aircraft entered the runway without authorization after a PA-34, registration I-MIRK, had completed its landing.
Simultaneously, the pilot of the I-MIRK mistakenly entered taxiway R2, which was closed to traffic, while attempting to vacate the runway. This error forced the air traffic controller to intervene and redirect the aircraft to taxiway R1. The confusion on the ground necessitated a go-around for a third aircraft, a Citation 560, registration HB-VMZ, which was on final approach.
The investigation
The ANSV investigation examined radar data, communications, and the actions of the flight crews and air traffic controllers. The investigation focused on why the OY-SIS crew entered the runway despite receiving a hold short instruction and why the I-MIRK pilot deviated from the assigned exit path. The investigation also reviewed the effectiveness of the ground radar, which was in an experimental phase at the time, in detecting the unauthorized movements.
Findings
- The primary cause of the runway incursion was the mental expectation created within the OY-SIS crew. Having been informed earlier in the taxi sequence that they were sixth in line, and observing previous aircraft being authorized to line up after landing, the crew acted in accordance with their expectations rather than the specific instruction.
- The long taxi duration and the sequence of departures contributed to this heightened expectation.
- The I-MIRK pilot, who was less experienced and unfamiliar with the Linate airport layout, entered the closed taxiway R2 due to a fear of overshooting the intended exit, R1. This error was compounded by a lack of visible signage.
- The use of experimental ground radar was instrumental in preventing a potential collision between the three aircraft involved.