What happened
On 8 July 2007, a Boeing 737-31S, registration G-THOG, was taxiing at Amsterdam Schiphol Airport following a scheduled passenger flight from the United Kingdom. After landing on runway 06, the runway controller suggested that the crew could extend their roll-out to the end of the runway to expedite their taxi to the gate. The crew accepted this suggestion.
As the aircraft continued past the runway end, it crossed the runway end lighting and entered the instrument landing system (ILS) protection area for runway 36R. This movement triggered an immediate safety response from air traffic control, who instructed an approaching Boeing 737 on final approach to runway 36R to perform a go-around to avoid a potential conflict.
The investigation
The investigation examined radio transcripts, radar plots, and statements from the flight crew and air traffic controllers. Investigators analyzed the physical runway markings, the status of the lighting systems, and the specific instructions provided by the runway controller. The inquiry also reviewed the regulatory framework for using dependent runways at Schiphol and the visibility conditions at the time of the event.
Findings
Several factors contributed to the incident. The primary cause was a misinterpretation of non-standard terminology used by the controller. While the controller intended for the aircraft to use a specific exit, the instruction to leave the runway at the end was not unequivocal. The crew interpreted the instruction literally, believing they were permitted to pass the red lights at the runway end.
Additional contributing factors included:
- A difference in experience regarding runway end lights; the captain noted that crossing such lights is common at other airports, whereas the controller did not expect the crew to pass them.
- The absence of a physical barrier or raised lighting to prevent the aircraft from crossing the threshold.
- The fact that the stop bar lights, which could have prevented the incursion, were not illuminated because visibility conditions were good.
Safety action
While the investigation focused on the lack of physical barriers and the use of non-standard phraseology, the report noted that the runway end lights were recessed into the concrete, making them physically passable. The investigation highlighted that the lack of unambiguous communication and the absence of a physical stop bar at the runway end left the ILS protection area vulnerable to such incursions.