The Dutch Safety Board (DSB) investigators have revealed that KLM Cityhopper pilots aborted the take-off at high speed (above 85 knots) after hearing that runway controller issued a take-off clearance to another aircraft for the same runway. The incident took place at Schiphol Airport in Amsterdam, the Netherlands on 27 July 2018.
According to the report in the safety board’s Quarterly Bulletin published on June 15, the agile action of the crew piloting their Embraer ERJ-190 bound for Edinburgh, Scotland, prevented a catastrophic accident.
After the E-190, located at the start of runway 18C, received take-off clearance a KLM Boeing 737-800 bound for Hamburg, Germany, was also cleared to line up and take off on the same runway, but from further down the 10,800ft runway.
The crew of the E190 started the take-off roll as they saw that the B737 was clear of the runway. But, when they heard that the B737 was also getting take-off clearance, they rejected take-off at high speed, above 85 knots.
Shortly afterward, the Runway Incursion Alerting System Schiphol (RIASS) generated a warning in the control tower, prompting the controller to withdraw the clearance of the E190. The report says that the take-off clearance given to the E190 led to a potential collision because both aircraft simultaneously had been authorized to access to the same part of the runway where high-energy aircraft movements take place.
“The RIASS was not an effective safety tool in this situation as this system generated an alarm only after the E190 already slowed down on its own initiative. The fact that both crews involved in the incident communicated and saw each other on the same radio frequency were effective safety means,” writes the report.
The Controller’s High-Workload
At the time of the incident, the runway controller was responsible for another two runways, which is considered as an operation of increased complexity. The controller was previously involved in two other incidents just before the serious incident.
About 23 minutes before the incident, a small plane crossing the airport towards the coast did not follow his instructions, endangering the take-offs from 18C where the serious incident took place. The controller said he was shocked, but indicated that he could continue his duty after consultation with his supervisor.
Approximately 4 minutes before the occurrence, he also authorized an aircraft to taxi on runway 18C through intersection W4 although he had issued take-off clearance to another aircraft on the same runway 15 seconds earlier. Immediately after the crew read back the taxi clearance, he withdrew it.
“It cannot be excluded that these events still had some effect on the mental load capacity of the runway controller at the time of the incident,” states the report.
It is clear from the report that the two other aerodrome-related safety events that occurred just before the serious incident and high workload of the runway controller largely contributed to the incident. Considering the fact that the system that is supposed to prevent such incidents or accidents did not function on time, if it had not been averted by the crew of E190, the incident could have led to a collision resulting in hundreds of casualties.