On April 18, 2001, a Cessna 172B (registration N4672L) was involved in an aviation accident near Lancaster, CA. Investigators recorded the probable cause as: The pilot's delay reversing course while flying toward rising terrain in a box canyon. Factors in the accident included a downdraft on the lee side of a ridge forming the box canyon, high density altitude, and the pilot's improper use of flaps. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A pilot attempting to climb out of a box canyon encountered a downdraft from ridge winds, leading to an involuntary descent and forced landing despite full power and flap use. No mechanical issues were found.
Incident Overview
A pilot reported that while attempting to climb the airplane out of a box canyon, the aircraft experienced an involuntary descent. Surface winds at 18 knots with gusts to 24 knots produced a downdraft on the lee side of a ridge forming one side of the canyon. The density altitude was 5,000 feet.
Pilot Report
The pilot stated that despite applying full engine power, the aircraft was unable to gain or maintain altitude, resulting in a forced landing. He also noted that he deployed a small amount of flaps to prevent the aircraft from settling.
Investigation Findings
No mechanical anomalies were found with the airplane. The circumstances point to the influence of terrain-induced wind conditions and high density altitude on aircraft performance.
What happened in the 18 Apr 2001 Cessna 172B accident near Lancaster, CA?
A pilot attempting to climb out of a box canyon encountered a downdraft from ridge winds, leading to an involuntary descent and forced landing despite full power and flap use. No mechanical issues were found.
What aircraft was involved and where did it happen?
The accident on 18 Apr 2001 involved a Cessna 172B, registration N4672L, at Lancaster, CA.
What was the probable cause of the accident?
The pilot's delay reversing course while flying toward rising terrain in a box canyon. Factors in the accident included a downdraft on the lee side of a ridge forming the box canyon, high density altitude, and the pilot's improper use of flaps.
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