This is an excerpt from a report made to the Aviation Safety Reporting System. The narrative is written by the pilot, rather than FAA or NTSB officials. To maintain anonymity, many details, such as aircraft model or airport, are often scrubbed from the reports.
While conducting traffic pattern takeoff and landing practice with a pre-checkride primary flight student, we encountered B737 wake turbulence during landing at approximately 50-75 feet above the runway.
Conditions were clear, wind was a light quartering headwind.
Student was advised to remain above the landing traffic flight path and to touchdown well past their touchdown point. As a prominent tire smoke cloud was evident, the touchdown point was easy to identify.
For two circuits around the pattern, the student stayed well above landing traffic flight path and properly offset slightly upwind during climb-out to avoid landing and departing wake turbulence.
On the third circuit, student was again advised to remain above and land long. Touchdown aim point was discussed after turning final to be well past the touchdown zone markers to remain above and land beyond, as before.
During short final for a practice short field landing, student changed aim point closer to the touchdown zone markers and entered a mild slip to lose altitude.
Approximately 5 seconds later at approximately 50-75 feet above the runway, a slight rock of the wings was felt, and about 1 second later the Cessna 172 entered an abrupt uncommanded left bank well past steep turn limits.
Student began correcting but was slow on the response, so I intervened and added full right aileron, full power, and was able to arrest the bank and descent.
Student was visibly and audibly shaken, but upon returning to the downwind leg was able to take control again and land without further incident.
As the instructor, this was an extremely valuable lesson for me as well.
I was uncomfortable with the student entering a slip at the point he did due to the potential for wake turbulence, however having flown numerous flights with this student I knew him to be well prepared for the check ride as he exhibited above average aircraft control, in particular during landing, for students with his flight time.
I felt we were still high enough to avoid wake turbulence and allowed him to continue. When we encountered the first wing rock, I was reaching for the yoke to initiate a go-around, but was already too late in taking corrective action to avoid the wake turbulence completely.
Thankfully, this event turned into nothing more than a valuable lesson for both of us.
The post-flight debrief focused mostly on the wake turbulence encounter, and the now obvious need to remain much higher and land further beyond the touchdown point of heavier aircraft.
Primary Problem: Ambiguous
ACN: 1911859
