What happened
Between 31 March and 20 May 2025, taxiway construction at Adelaide Airport, South Australia, necessitated a temporary displacement of the runway 23 take-off start of take-off (SOT) position. To accommodate the works, the SOT was moved 65 and 508 meters beyond its normal location, creating a new temporary threshold. During this period, 13 occurrences were identified where aircraft began their take-off from the displaced threshold rather than the intended SOT position. This error created a significant safety risk, as flight crews were utilizing takeoff performance data calculated for the shorter, intended runway length. While some incidents were prevented by air traffic control (ATC) or pilot inquiries, several aircraft departed from the incorrect location during both day and night operations.
The investigation
The ATSB examined the effectiveness of the information provided to flight crews, including the NOTAM, ATIS, and physical airfield markings. The investigation found that while crews were aware of the construction and the existence of a displaced threshold, the visual cues for the new SOT position were highly ambiguous. During daylight, the white arrows and threshold lights—which were more prominent than the SOT line—unintentionally signaled pilots to continue forward. At night, the transition from green taxiway lighting to red edge lighting was not distinct enough to clearly mark the new start point. Furthermore, the red edge lights, intended to warn landing aircraft, did not intuitively signal a takeoff start point to departing pilots. The investigation also noted that the ATIS lacked specific details regarding the SOT location, and the initial NOTAM used inconsistent terminology and failed to mention the specific white line marking the SOT.
Findings
- The primary cause of the errors was the misidentification of the runway 23 start position due to confusing temporary markings and lighting.
- The initial NOTAM contained inconsistent terminology and failed to reference the white line marking the SOT position.
- Red runway edge lights were not easily visible to pilots during daylight hours.
- In one instance, an air traffic controller failed to correct two incorrect readbacks regarding the runway end, which likely contributed to the error.
- There is a lack of standardized guidance in the Civil Aviation Safety Regulations Part 139 Manual of Standards for visual aids to highlight a displaced takeoff position when it does not coincide with a taxiway or runway intersection.
Safety message
- Proactive measures by aircraft operators to emphasize the correct takeoff position and the use of specific intersection data helped mitigate the number of incidents.
- ATC interventions and pilot queries to confirm takeoff positions were effective in preventing further occurrences.