Narrative:

I was cleared to land on runway 28R at myf, ca. I had a normal approach, though on short final there was turbulence, and crossed the threshold at 70 KTS, the recommended speed for the C172SP given the headwind component. When I was on short final the tower informed me that the wind was 250 degrees or 260 degrees (I do not recall which) at 18 KTS, gusting to 25 KTS. I mentally calculated that the direct crosswind was no more than 9 KTS, with gusts to 12 KTS or 13 KTS, with the plane's demonstrated crosswind component of 15 KTS. When over the runway I tracked the centerline until the left wheel touched down. After the right wheel touched down, the plane shifted slowly to the right of the centerline and decelerated. About 100-150 ft from where I expected to stop, the left wing suddenly lifted and the left wheel left the pavement. The plane swerved to the right, toward the grass. By the time I got the left wheel back down, the plane was aiming for the grass at about a 30 degree angle to the runway. I thought that if I tried to turn it abruptly to the left, the plane could be kept mainly on the runway with only a short excursion onto the grass, possibly only on the right wheel, but not without rolling over one or more runway lights, so I let the plane continue onto the grass, exiting between lights. I lightly applied the brakes and allowed the plane to decelerate on the grass. It came to a stop on the intersecting runway 23/5 (which had been notamed as OTS for the day due to airship operations at one end). I estimate that the plane crossed 50-100 ft of grass before entering runway 23/5. That the plane moved off the centerline after touchdown indicated I did not maintain enough aileron. Then, when the left wing lifted, my reaction to what may have been a change in wind direction and magnitude was too slow and insufficiently vigorous. There were no damages to the plane, its occupant, the runway lights, or anything else.

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Original NASA ASRS Text

Title: SMA PVT PLT VEERS OFF RWY DURING XWIND LNDG AND WINDS UP ON ANOTHER RWY.

Narrative: I WAS CLRED TO LAND ON RWY 28R AT MYF, CA. I HAD A NORMAL APCH, THOUGH ON SHORT FINAL THERE WAS TURB, AND CROSSED THE THRESHOLD AT 70 KTS, THE RECOMMENDED SPD FOR THE C172SP GIVEN THE HEADWIND COMPONENT. WHEN I WAS ON SHORT FINAL THE TWR INFORMED ME THAT THE WIND WAS 250 DEGS OR 260 DEGS (I DO NOT RECALL WHICH) AT 18 KTS, GUSTING TO 25 KTS. I MENTALLY CALCULATED THAT THE DIRECT XWIND WAS NO MORE THAN 9 KTS, WITH GUSTS TO 12 KTS OR 13 KTS, WITH THE PLANE'S DEMONSTRATED XWIND COMPONENT OF 15 KTS. WHEN OVER THE RWY I TRACKED THE CTRLINE UNTIL THE L WHEEL TOUCHED DOWN. AFTER THE R WHEEL TOUCHED DOWN, THE PLANE SHIFTED SLOWLY TO THE R OF THE CTRLINE AND DECELERATED. ABOUT 100-150 FT FROM WHERE I EXPECTED TO STOP, THE L WING SUDDENLY LIFTED AND THE L WHEEL LEFT THE PAVEMENT. THE PLANE SWERVED TO THE R, TOWARD THE GRASS. BY THE TIME I GOT THE L WHEEL BACK DOWN, THE PLANE WAS AIMING FOR THE GRASS AT ABOUT A 30 DEG ANGLE TO THE RWY. I THOUGHT THAT IF I TRIED TO TURN IT ABRUPTLY TO THE L, THE PLANE COULD BE KEPT MAINLY ON THE RWY WITH ONLY A SHORT EXCURSION ONTO THE GRASS, POSSIBLY ONLY ON THE R WHEEL, BUT NOT WITHOUT ROLLING OVER ONE OR MORE RWY LIGHTS, SO I LET THE PLANE CONTINUE ONTO THE GRASS, EXITING BTWN LIGHTS. I LIGHTLY APPLIED THE BRAKES AND ALLOWED THE PLANE TO DECELERATE ON THE GRASS. IT CAME TO A STOP ON THE INTERSECTING RWY 23/5 (WHICH HAD BEEN NOTAMED AS OTS FOR THE DAY DUE TO AIRSHIP OPS AT ONE END). I ESTIMATE THAT THE PLANE CROSSED 50-100 FT OF GRASS BEFORE ENTERING RWY 23/5. THAT THE PLANE MOVED OFF THE CTRLINE AFTER TOUCHDOWN INDICATED I DID NOT MAINTAIN ENOUGH AILERON. THEN, WHEN THE L WING LIFTED, MY REACTION TO WHAT MAY HAVE BEEN A CHANGE IN WIND DIRECTION AND MAGNITUDE WAS TOO SLOW AND INSUFFICIENTLY VIGOROUS. THERE WERE NO DAMAGES TO THE PLANE, ITS OCCUPANT, THE RWY LIGHTS, OR ANYTHING ELSE.

Data retrieved from NASA's ASRS site as of July 2007 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.