Narrative:

While on final approach to make a full stop 3-point landing in a tail dragger on runway 31 at pao; I informed my student that the winds socks at the approach and departure ends of the runway indicated different wind directions and speeds. The ATIS information was reporting winds variable at 3 KTS; as was indicated by the approach-end windsock; but during this approach the departure-end windsock indicated a steady wind approximately 350 degrees at 7 to 9 KTS. The student; who was flying the airplane; finished a normal approach to a full-stall 3-point touchdown approximately abeam the bravo taxiway. While decelerating from touchdown speeds during the landing roll out; the airplane encountered the stronger north northwest wind indicated by the departure-end windsock. At that moment the airplane began to yaw to the right; into the wind; and the student attempted to correct with opposite rudder/brake inputs. The student's rudder/brake inputs; however; were somewhat delayed and lacked adequate aileron deflection into the wind; such that the airplane swerved twice with increasing yaw; at which point I took the flight controls in order to prevent a ground loop. I took the controls during the second swerve which was in the direction of the north northwest wind. I was able to stop the increasing rate of yaw by applying maximum left-braking force and full opposite-aileron to prevent ground looping; but the plane had reached the right-hand edge of runway 31 by this time; just past the charlie taxiway on the opposite side of the runway. The airplane continued off the runway into some very low brush on flat; muddy terrain along the runway edge; during which time I regained directional control. With the airplane still in motion; I was able to steer back onto runway 31 through the low brush without hitting any airport infrastructure. The entire excursion off the runway lasted approximately 10 to 15 seconds; and extended approximately 30 ft from the runway edge. Upon steering back onto runway 31; I informed the tower that the airplane was again under control and that we were exiting at taxiway echo. Upon exiting runway 31 we contacted ground control; and requested taxi to the wash rack to both inspect and rinse the mud off of the airplane. During the post flight briefing; the student and I; the instructor; both agreed that it was the lack of timely and fully-correct crosswind control-inputs by the student that led to the airplane swerving across and off the runway edge. The student also admitted that his concentration level that day might have been a contributing factor. Other contributing factors were the poor efficacy of the brakes on the this type tail dragger to halt the excess rate of yaw caused by the unmitigated swerving across the runway; as well as the crosswind being more sudden than anticipated. As for providing supervision during crosswind landings; I intend to follow student control inputs even more closely in the future in order to prevent increasing yaw during landing roll out; and to provide more tangible instructional feedback in applying proper corrective crosswind inputs.

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Original NASA ASRS Text

Title: A tailwheel instructor reported that during a three-point full stop landing; a wind shift was encountered which caused the aircraft have a 30 FT runway excursion. No damage to the aircraft or airport property occurred.

Narrative: While on final approach to make a full stop 3-point landing in a tail dragger on Runway 31 at PAO; I informed my student that the winds socks at the approach and departure ends of the runway indicated different wind directions and speeds. The ATIS information was reporting winds variable at 3 KTS; as was indicated by the approach-end windsock; but during this approach the departure-end windsock indicated a steady wind approximately 350 degrees at 7 to 9 KTS. The student; who was flying the airplane; finished a normal approach to a full-stall 3-point touchdown approximately abeam the Bravo Taxiway. While decelerating from touchdown speeds during the landing roll out; the airplane encountered the stronger north northwest wind indicated by the departure-end windsock. At that moment the airplane began to yaw to the right; into the wind; and the student attempted to correct with opposite rudder/brake inputs. The student's rudder/brake inputs; however; were somewhat delayed and lacked adequate aileron deflection into the wind; such that the airplane swerved twice with increasing yaw; at which point I took the flight controls in order to prevent a ground loop. I took the controls during the second swerve which was in the direction of the north northwest wind. I was able to stop the increasing rate of yaw by applying maximum left-braking force and full opposite-aileron to prevent ground looping; but the plane had reached the right-hand edge of Runway 31 by this time; just past the Charlie Taxiway on the opposite side of the runway. The airplane continued off the runway into some very low brush on flat; muddy terrain along the runway edge; during which time I regained directional control. With the airplane still in motion; I was able to steer back onto Runway 31 through the low brush without hitting any airport infrastructure. The entire excursion off the runway lasted approximately 10 to 15 seconds; and extended approximately 30 FT from the runway edge. Upon steering back onto Runway 31; I informed the Tower that the airplane was again under control and that we were exiting at Taxiway Echo. Upon exiting Runway 31 we contacted Ground Control; and requested taxi to the wash rack to both inspect and rinse the mud off of the airplane. During the post flight briefing; the student and I; the instructor; both agreed that it was the lack of timely and fully-correct crosswind control-inputs by the student that led to the airplane swerving across and off the runway edge. The student also admitted that his concentration level that day might have been a contributing factor. Other contributing factors were the poor efficacy of the brakes on the this type tail dragger to halt the excess rate of yaw caused by the unmitigated swerving across the runway; as well as the crosswind being more sudden than anticipated. As for providing supervision during crosswind landings; I intend to follow student control inputs even more closely in the future in order to prevent increasing yaw during landing roll out; and to provide more tangible instructional feedback in applying proper corrective crosswind inputs.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.