On Wednesday 31 May 2017, a runway incursion occurred at Amsterdam Airport Schiphol. This situation arose because an aircraft received a take-off clearance while a bird patrol vehicle had not left the so-called Polderbaan. 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
The situation arose when a take-off clearance was given to an aircraft type Bombardier Regional Jet (CRJ9), while a bird patrol vehicle was inspecting the runway for birds. The air traffic controller was not aware of the presence of the bird watch on the Polderbaan at that moment. Shortly after the take-off clearance the bird patrol driver reported via the radio that he was still on the runway. The air traffic controller immediately withdrew the take-off clearance of the Bombadier. After the bird patrol had left the runway the Bombardier departed from Schiphol Airport without delay.
A Bombardier taxis to the Polderbaan runway for departure. A historic amphibious aircraft of the type Catalina crosses Schiphol’s local traffic control zone from the northwest in the direction of the IJmeer. The birdwatch at Schiphol is driving near the Polderbaan.
The air traffic controller is in contact with the Catalina and decides to instruct the aircraft to fly via Tower West and Tower Centre on its way to IJmeer. Taking this route minimizes any disruption caused by the Catalina’s flight path for other Schiphol traffic. Coordination takes place between Tower West, Tower Centre and Approach Control.
Birdwatch given permission for runway check
Because the traffic situation is fairly quiet and it is nearly time for the birdwatch to conduct the regular planned runway check, the Tower West crew informs the birdwatch that it can proceed with its runway check. At that moment, the birdwatch is still on the peripheral road of the Polderbaan.
While Tower West , Tower Centre and approach control are in coordination about the Catalina’s flight path, the birdwatch is given permission to drive onto the Polderbaan runway via entry V4. The air traffic controller did not hear this permission. The tower crew did not use the runway occupied strip, a visual aid which not only enables the control tower crew to see that the runway is occupied, but also the number of aircraft on the runway. Furthermore, the runway occupied signal, an acoustic aid indicating an occupied runway, was not switched on.
Bombardier given taxi instructions
The taxiing Bombardier contacts the ground controller and is instructed to taxi to entry V4. It is then informed that a runway check is being performed there. A little later, the air traffic controller decides to allow the Bombardier to taxi to entry V3, to avoid a potential conflict between the planned start of the Bombardier and the Catalina’s flight path. The ground controller changes the taxi instruction of the Bombardier to entry V3. As it approaches V3, the Bombardier is switched to the frequency of the air traffic controller.
Bombardier receives clearance for takeoff
The air traffic controller instructs the Bombardier to enter the Polderbaan and to wait once it is on the runway. This is to check that the flight path of the passing Catalina is sufficiently distant from the departure route of the Bombardier. If this is the case, the air traffic controller will give the Bombardier clearance for takeoff.
Clearance for takeoff Bombardier withdrawn
At that moment, the birdwatch is driving in a northerly direction and is halfway up the Polderbaan. Because the birdwatch is listening in to the frequency of the air traffic controller, they hear that an aircraft has been given clearance for takeoff. The birdwatch immediately informs the ground controller that they are on the runway. The air traffic controller immediately withdraws the Bombardier’s clearance for takeoff. The Bombardier has not yet started the takeoff procedure and the captain confirms the withdrawn clearance instruction.
After the birdwatch has completed the runway check and left the runway, the Bombardier is given permission to depart. The flight leaves without problems.
LVNL has a Runway Incursion Alerting System Schiphol (RIASS). For this incident, RIASS did not generate a warning, because the Bombardier had not yet started and therefore did not have sufficient speed to trigger the RIASS.
The aircraft was around two kilometres away from the birdwatch. There was therefore no risk of collision.
While clearing the Bombardier for take-off, the tower crew was not aware of the presence of the birdwatch on the Polderbaan runway. The crew did not use the runway occupied strip. For that reason, the runway occupied signal was not used.
Immediately after finding that the birdwatch was still on the runway, corrective instructions were given to the Bombardier. There was no risk of collision.
Follow-up to the investigation
From the safety investigation, it appears that the runway occupied strip method is not infallible. After an investigation, it was decided that the runway occupied strip must be compulsory for both Tower Centre and Tower West.
Attention will also be given to the fact that good alertness and cooperation, even at quieter moments, is vitally important.
Classification: major incident