The Narrow Runway Illusion: N6500W's Final Approach at Prescott

A night-currency flight aligned with a narrow runway after an overshoot, then descended into desert terrain short of the runway.

On August 29, 2018, Cessna P210 N6500W was conducting practice takeoffs and landings at Prescott Regional Airport, Arizona, to build night currency. The pilot initially requested Runway 21L, which was 150 ft wide, but accepted the parallel Runway 21R after ATC advised that the 21L pattern was full. Runway 21R was only 60 ft wide. The aircraft did not fly a pattern parallel to 21R, overshot the final approach course during the base-to-final turn, then corrected toward the runway. The tower questioned the alignment and then instructed the pilot to go around. The aircraft nevertheless continued toward the runway and struck a berm about 1,900 ft short.

Accident Facts

The Runway Choice

The pilot's original request was for Runway 21L, the wider 150-ft runway. ATC advised that the traffic pattern was full and offered 21R, the parallel 60-ft runway. The pilot accepted the alternative. The NTSB considered the difference in runway width important to the visual approach picture at night.

The Pattern Did Not Stay Parallel

Radar data showed that the aircraft joined a right traffic pattern for 21R, but the downwind track was not parallel to the runway. The airplane moved toward the approach end and then entered a long teardrop-shaped 180° turn. About 2.8 nm from the approach end, the heading turned toward the runway.

ATC Questioned the Alignment

At 20:32:59 the tower asked, “just verifying you're lining up for runway 21R.” Four seconds later the pilot confirmed the runway. At 20:33:19, only sixteen seconds after that confirmation, the controller instructed the pilot to go around. The radar track nevertheless continued toward the runway.

Why the Runway Width Mattered

The NTSB concluded that the narrow runway, viewed in dark-night conditions without a natural horizon or many external visual references, could create a runway-width illusion. A pilot may interpret the visual size of a narrow runway as indicating that the aircraft is too high and respond by descending. In N6500W's case, the investigation found that the pilot descended toward terrain short of the runway.

The PAPI Was Available

Runway 21R had a precision approach path indicator intended to provide a visual glidepath reference at night. The NTSB noted that the pilot also had competing visual tasks, including maintaining separation from traffic using Runway 21L and aligning with the narrower runway. The report also considered the pilot's recency of nighttime experience.

No Preexisting Mechanical Failure

Examination of the recovered wreckage did not reveal a preexisting mechanical anomaly that would have prevented normal operation. An exhaust-system crack was identified, but investigators did not determine that it caused the accident. The aircraft's final approach and impact were therefore analyzed as an approach and visual-reference problem rather than a primary aircraft failure.

What the Records Show

The NTSB determined that the pilot misjudged distance and altitude from the runway and failed to maintain an approach path providing terrain clearance because of a visual illusion in dark-night conditions.

Conclusion

N6500W reached the runway environment but never reached a safe height above the terrain short of it. The investigation identified a specific visual illusion associated with the narrow runway and dark conditions, while the available mechanical evidence did not show an aircraft failure that forced the descent.

Sources & Reconstruction Note

• https://data.ntsb.gov/Docket?NTSBNumber=WPR18FA245