What happened
During a manual approach to land at Darlot, the pilot experienced a period of high workload while managing the descent profile through altitude and distance cross-checks. As the aircraft approached the runway, raised dust became visible, prompting the pilot to check for potential vehicle activity on the runway. This dust also obscured the right-hand runway and its associated strip markers.
While the pilot initially discounted the possibility of a vehicle, the obscured view led to a misidentification of the runway's position. The pilot incorrectly identified the left runway strip markers as the left runway markers. Because the pilot was seated in the left seat, they used the aiming point markers located on the left side of the runway strip as their primary visual guidance cue, which ultimately led to the aircraft landing in the runway strip to the left of the actual runway.
The investigation
The investigation examined the pilot's visual processing and the configuration of the airfield. It was noted that the placement of aiming point markers at the unsealed runways used by the operator lacked standardization regarding both the type of markers and their position relative to the runway. The pilot, drawing on experience from other unsealed runways, expected markers to be positioned adjacent to the runway itself. Consequently, the pilot did not recognize that the markers on the left side of the strip indicated a landing path offset from the centerline.
Furthermore, the investigation considered the physiological impact of visual scanning. When a pilot focuses on the runway centerline, markers that are laterally displaced from that center move from central to peripheral vision much sooner. Specifically, markers displaced by 45 m move to peripheral vision at three times the distance compared to markers located 15 m from the centerline. This shift can divert a pilot's scan away from the critical centerline during the landing phase.
Findings
- Raised dust obscured the right-hand runway and strip markers, preventing a clear view of the full runway environment.
- The pilot incorrectly identified left runway strip markers as the left runway markers due to the obscured right side of the runway.
- The use of aiming point markers at the operator's unsealed runways was not standardized in terms of marker type or position.
- The lateral displacement of markers from the runway centerline can cause visual cues to move into peripheral vision prematurely, potentially diverting the pilot's scan during a critical stage of flight.