What happened
On 29 January 2009, a Cessna Citation II/C550, registration G-JBIS, was performing a charter flight from Berlin to Amsterdam Schiphol Airport. While on final approach to runway 22, the flight crew received landing clearance from the runway controller. At approximately the same time, a towing combination transporting an Airbus 330 requested permission to cross runway 22 at taxiway intersection G2.
Following the departure of a previous towing vehicle, the runway controller deactivated the stop bar lights. The tower assistant subsequently granted the second towing vehicle permission to proceed across the runway. The driver of the towing combination noted seeing an aircraft on approach but, because the stop bar lights were extinguished, assumed the aircraft was not intending to land on runway 22. As the vehicle entered the runway, the tower assistant identified the G-JBIS on radar and visually confirmed it was on final approach. An immediate instruction was issued for the vehicle to stop, prompting the crew of the Cessna Citation II/C550 to initiate a go-around. The aircraft successfully completed a visual circuit and landed on runway 22 without further incident.
The investigation
The investigation examined statements from air traffic control staff, towing vehicle personnel, and the flight crew, alongside radio transcripts and radar data. Investigators analyzed the sequence of clearances provided by the runway controller and the tower assistant, specifically focusing on the management of the stop bar lights and the timing of the crossing permissions.
Findings
- The runway controller granted landing clearance to the aircraft while simultaneously allowing the runway to be used by ground traffic.
- The deactivation of the stop bar lights removed a critical visual safeguard that would have prevented a runway incursion.
- The driver of the towing vehicle relied on the status of the stop bar lights to judge the intentions of approaching aircraft.
- The simultaneous clearance of an approaching aircraft and a crossing vehicle created a high risk of a runway incursion.
- A lack of active traffic in the tower may have led to a loss of situational awareness regarding the landing aircraft's arrival time.