Evektor-Aerotechnik A S HARMONY LSA N377YG accident near Santa Ana, California

Probable cause

A loss of airplane control due to wake turbulence resulting from the instructor pilot’s decision to continue the landing into a drifting wake vortex.

NTSB analysis

The light sport airplane (LSA) was on a day, visual flight rules approach to runway 20L when the tower controller cautioned the student pilot of possible wake turbulence from an airliner that was on approach to land on parallel runway 20R just ahead of the LSA. The student pilot in the LSA acknowledged the caution and continued the approach to land. About 40 ft above ground level (agl) and about 450 ft from the runway threshold, the accident airplane entered a rapid right roll, subsequently impacting the ground.

Surveillance video of the accident showed that about 49 seconds before the accident, a narrow-body airliner made an approach and landed on runway 20R. The lateral distance between runway 20R and 20L was about 390 ft. The video then showed the LSA approach the runway 20L threshold and enter an uncommanded right roll.

The prevailing wind about the time of the accident was 3 knots from 240°. The wake vortex generated by the landing airliner likely drifted to the parallel runway with the southwesterly wind, where it was subsequently encountered by the accident airplane as it approached runway 20L. FAA Advisory Circular (AC) 90-23G, section 11, noted that, when landing behind a larger aircraft on a parallel runway closer than 2,500 ft apart and considering the relationship between the runway threshold locations, the relative glideslope descent paths and possible vortex drift will likely prevent wake turbulence accidents of this nature. As the AC states, “The pilot should exercise vortex visualization and avoidance procedures using the same degree of awareness as in collision avoidance.” The pilot should have, as the AC states, established a glidepath to a touchdown point that was “above and beyond the touchdown point of the larger preceding aircraft.” Landing beyond the touchdown point of the larger preceding airplane would likely have averted the light sport airplane’s encounter with wake turbulence.

Text from the NTSB. Open the NTSB docket for WPR24LA085 for the full record.