Narrative:

I was on a visual approach to brackett airport (poc); landing on runway 26L. My main landing gear touched down about 200 ft past the 1000 ft marker and my nosewheel shortly thereafter. I began to apply even brake pressure when the aircraft yawed sharply to the right. I applied pressure on the left rudder pedal in order to correct the yaw and maintain directional control. The left rudder input did not change the direction of the aircraft or stop the yaw. I felt increasing the amount of left rudder input would only cause a sharp yaw to the left; increasing the centrifugal force to the right and possibly rolling the aircraft. Therefore; I held the left rudder pressure constant; which eventually stopped the yaw to the right and regained directional control. Once directional control was regained; the aircraft was at a 45 degree angle to the runway and heading for the right edge. I felt my safest option was to keep the aircraft headed straight; maintain directional control and reapply brake pressure. Deciding to not change the direction of the aircraft caused me to exit the runway surface and enter the grass area north of runway 26L. I continued to apply the brakes as the aircraft came to a stop on taxiway east. I advised the tower that we were ok and were cleared to taxi to parking. I inspected the aircraft and did not find any visible damage. Before taking off; I tested the brakes and found them to work properly. I do not know what caused the sudden yaw during landing; but I am confident my corrective action prevented substantial aircraft damage and possibly an accident.

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Original NASA ASRS Text

Title: A C172 LANDED WITH AN UNSPECIFIED CTL ANOMALY CAUSING THE ACFT TO EXIT THE RWY BUT RESULTING IN NO HARM OR INJURY.

Narrative: I WAS ON A VISUAL APCH TO BRACKETT ARPT (POC); LNDG ON RWY 26L. MY MAIN LNDG GEAR TOUCHED DOWN ABOUT 200 FT PAST THE 1000 FT MARKER AND MY NOSEWHEEL SHORTLY THEREAFTER. I BEGAN TO APPLY EVEN BRAKE PRESSURE WHEN THE ACFT YAWED SHARPLY TO THE R. I APPLIED PRESSURE ON THE L RUDDER PEDAL IN ORDER TO CORRECT THE YAW AND MAINTAIN DIRECTIONAL CTL. THE L RUDDER INPUT DID NOT CHANGE THE DIRECTION OF THE ACFT OR STOP THE YAW. I FELT INCREASING THE AMOUNT OF L RUDDER INPUT WOULD ONLY CAUSE A SHARP YAW TO THE L; INCREASING THE CENTRIFUGAL FORCE TO THE R AND POSSIBLY ROLLING THE ACFT. THEREFORE; I HELD THE L RUDDER PRESSURE CONSTANT; WHICH EVENTUALLY STOPPED THE YAW TO THE R AND REGAINED DIRECTIONAL CTL. ONCE DIRECTIONAL CTL WAS REGAINED; THE ACFT WAS AT A 45 DEG ANGLE TO THE RWY AND HEADING FOR THE R EDGE. I FELT MY SAFEST OPTION WAS TO KEEP THE ACFT HEADED STRAIGHT; MAINTAIN DIRECTIONAL CTL AND REAPPLY BRAKE PRESSURE. DECIDING TO NOT CHANGE THE DIRECTION OF THE ACFT CAUSED ME TO EXIT THE RWY SURFACE AND ENTER THE GRASS AREA N OF RWY 26L. I CONTINUED TO APPLY THE BRAKES AS THE ACFT CAME TO A STOP ON TXWY E. I ADVISED THE TWR THAT WE WERE OK AND WERE CLRED TO TAXI TO PARKING. I INSPECTED THE ACFT AND DID NOT FIND ANY VISIBLE DAMAGE. BEFORE TAKING OFF; I TESTED THE BRAKES AND FOUND THEM TO WORK PROPERLY. I DO NOT KNOW WHAT CAUSED THE SUDDEN YAW DURING LNDG; BUT I AM CONFIDENT MY CORRECTIVE ACTION PREVENTED SUBSTANTIAL ACFT DAMAGE AND POSSIBLY AN ACCIDENT.

Data retrieved from NASA's ASRS site as of January 2009 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.