On Sunday afternoon 28 February, a runway incursion occurred at Amsterdam Airport Schiphol. This situation arose because a towing truck, towing an aircraft from Schiphol-Oost to Schiphol-Center, crossed runway 36R while an aircraft was approaching for landing on this runway. The runway controller instructed the approaching aircraft to abort the approach and to go around. Minutes later the the aircraft landed safely. LVNL has reported this incident to the Dutch Safety Board and is conducting its own investigation.
The term 'runway incursion' refers to any occurrence at an aerodrome involving the incorrect presence of an aircraft, vehicle or person on the protected area of a surface designated for the landing and take-off of aircraft.
LVNL’s primary safety task is to maintain the separation of aircraft in the air, and between vehicles and other obstacles when on the ground. Air traffic controllers internally report any safety related occurrence, with the objective to learn lessons from those occurrences, thereby reducing the chance that similar occurrences will take place again in the future. All reported occurrences are investigated by LVNL, as part of LVNL’s ongoing commitment to improve safety.
Description of the situation and results of the investigation
Towing truck en route
The towing truck is en route with a Boeing 787 from M platform in Schiphol-East to F pier in Schiphol-Centre. In the course of this operation, the combination needs to cross two runways: Oostbaan (04/22) and Aalsmeerbaan (18L/36R). At that point in time, Amsterdam Airport Schiphol has already transferred the supervision of both runways to Air Traffic Control the Netherlands (LVNL) - Aalsmeerbaan for the past 15 minutes or so and Oostbaan for over 4 hours.
Initially, the driver of the towing truck maintains radio contact with the Apron Controller (a staff member of Amsterdam Airport Schiphol). Before arriving at the Oostbaan intersection, the towing truck driver establishes contact with the Control Tower Assistant (a staff member of Air Traffic Control the Netherlands) – in accordance with the procedure adopted for crossing runways that are under the supervision of LVNL.
The Control Tower Assistant receives permission from the Runway Controller to allow the combination to cross Oostbaan via taxiway G4. The Control Tower Assistant communicates this permission to the towing truck driver. After passing the intersection, the towing truck driver switches back to the radio frequency for communicating with apron control – once again in accordance with procedure. After this, the combination proceeds via taxiway G4, eventually arriving at the intersection with Aalsmeerbaan after turning onto taxiway E3.
Aircraft approaching Aalsmeerbaan
In the meantime, an approaching Embraer 190 has contacted the Runway Controller of Aalsmeerbaan. The Runway Controller grants the Embraer landing clearance when the aircraft is flying approximately four kilometres from the runway threshold.
Towing truck drives onto Aalsmeerbaan, Embraer makes go-around
The Control Tower Assistant monitors the combination as it moves along taxiways G4 and E3 and expects the towing truck driver to contact the tower (according to procedure) before the combination starts crossing Aalsmeerbaan. This does not happen, however, because the Apron Controller does not instruct the driver to switch to the tower frequency.
As soon as the towing truck passes the illuminated stop bar at taxiway E3, the Control Tower Assistant instructs the driver to wait. There is no response from the driver, and the combination continues on its way.
Shortly before, the Control Tower Assistant has conferred with the Runway Controller about a suitable moment for allowing the towing truck to cross the runway. Consequently, the Runway Controller is already aware of the combination. Immediately after it becomes clear that the towing truck has driven onto the runway, the Runway Controller instructs the approaching Embraer to abort its approach and make a go-around.
The flight crew immediately follow these instructions. The combination continues its path across Aalsmeerbaan, after which it moves off the runway again. The Embraer flies past the rear of the towing truck, climbing back to a height of approximately 1,200 feet (over 365 metres).
Just over ten minutes later, the Embraer lands safely.
Permission to cross
The procedure for crossing runways that are under the supervision of LVNL stipulates that the Apron Controller – as was the case when the combination approached the intersection with Oostbaan – informs the towing truck driver that he or she needs to contact the Control Tower Assistant before the combination starts moving across Aalsmeerbaan. However, this does not occur in this case, because the Apron Controller assumes that Aalsmeerbaan is not under the supervision of LVNL. The Apron Controller consequently gives the towing truck driver permission to cross the runway.
This is due to the fact that in situations where a runway is not under the supervision of air traffic control, granting towing truck drivers permission to cross the runway has been delegated to Apron Control.
Stop bar and flashing lights
A stop bar has been installed at the E3 intersection with Aalsmeerbaan. Vehicles are never allowed to pass an illuminated stop bar. In addition, the E3 taxiway is also lined by flashing lights (runway guard lights, also known as ‘wig-wags’), which warn air crews and drivers that they are approaching an active runway. After failing to notice either the stop bar or the runway guard lights, the towing truck driver drives the pushback combination onto Aalsmeerbaan.
We have observed that the combination moved onto Aalsmeerbaan because:
- The Apron Controller gave permission to the tug driver to cross Aalsmeerbaan;
- The driver failed to stop at either the illuminated stop bar or the lit runway guard lights.
Classification: significant incident
The procedure for crossing runways has been changed in response to the findings of the investigation conducted by Air Traffic Control the Netherlands and Amsterdam Airport Schiphol.
Following this change in procedure, all runway crossings are henceforth handled by the Control Tower Assistant and no longer partly delegated to Apron Control. This means that in the direction of runway crossings, there is no longer a distinction between runways that are under LVNL’s supervision and those that are not. This avoids confusion and prevents incidents as set out above from occurring.