What aircraft was involved and where did it happen?

The accident on 2021-07-27 involved a Boeing B737-400, at SG.

What was the probable cause of the accident?

The incident was caused by a combination of air traffic controller distraction from an intermittent alarm and expectation bias within the flight crew, which prevented the timely detection of unlit runway lights.

Unlit Runway Lights During Changi Airport Take-off

An Airbus A320 departed Changi Airport with all runway lights switched off, following a series of controller distractions and crew expectation bias.

What happened

On 27 July 2021, at approximately 2011h, a JetStar Asia Airbus A320, registration 9V-JSM, performed a rolling take-off from Runway 20L at Changi Airport. During the approach to the runway, the flight crew noted that while the runway edge lights were active, the centerline lights were not. The pilot-in-command determined that the visible lighting met the airline's standard operating procedures for night operations and proceeded with the departure. Shortly after lifting off, the crew realized that the runway edge lights had also gone out and discovered that the entire runway lighting system was actually inactive. The runway controller subsequently switched the lights on, and the flight continued to its destination in Jakarta without further incident.

The investigation

The investigation focused on why the runway lights remained unlit during a night operation. Investigators examined the air traffic controller's workstation and found that a maintenance-related aural alarm had been sounding intermittently for nearly 40 minutes prior to the incident, causing significant distraction. The investigation also reviewed the visibility of Runway 3's specific lighting configuration from the Changi East Tower. A night taxi trial using the same aircraft type confirmed that the directional nature of the new bi-directional lights made them difficult to verify visually from the tower. Furthermore, the investigation looked into the graphical interface of the Advanced Surface Movement Guidance and Control System (ASMGCS), which appeared too cluttered for controllers to quickly discern the light status.

Findings

The runway controller failed to switch on the airfield lights due to distraction from a persistent aural alarm.
The flight crew experienced expectation bias, assuming the runway end lights were functional because the edge lights were visible.
The air traffic controller's reliance on the ASMGCS display was hindered by a cluttered graphical presentation that obscured the lights' status.
The directional design of the Runway 3 lighting made visual verification from the tower difficult.
The decision-making process for switching on lights was subjective, relying on the controller's judgment of darkness rather than a fixed schedule.

Safety action

Following the incident, the aircraft operator implemented recurrent training focused on crew resource management, specifically regarding assertiveness and active monitoring. The airline also issued new standing orders requiring pilots to verify lighting configurations and seek clarification from ATC if any discrepancy is noted. The Air Navigation Service Provider (ANSP) has since enhanced the ASMGCS graphical display, installed a sunset-based alert system to remind controllers to activate airfield lighting, and provided controllers with standardized sunrise and sunset tables.