Date: 201206
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Daylight
Aircraft: PA-32 Cherokee Six/Lance/Saratoga/6X
Operator: Personal
Operating under: Part 91
Flight plan: VFR
Mission: Personal
Flight phase: Landing
ATC / advisory: Tower ZZZ
Reporter organization: Personal
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Flight Instructor
Human factors: Workload; Confusion; Distraction; Situational Awareness
Anomaly: Ground Event / Encounter Loss Of Aircraft Control; Ground Excursion Runway; Inflight Event / Encounter Weather / Turbulence
Detector: Person Flight Crew
When detected: In-flight; Taxi
Result: Flight Crew Took Evasive Action
Contributing factors: Aircraft; Airport; Environment - Non Weather Related
Primary problem: Ambiguous

Narrative: I was cleared for landing on Runway 19. Conditions were VMC with winds from 250 at approximately 8 with gusts to 13 KTS. The approach was absolutely normal in all respects. In fact; I routinely fly out of an airport in the mountains and this mountain airport is almost identical in all relevant aspects; mountain setting with crosswinds out of the west; altitude and density altitude conditions on any given day. Immediately upon touchdown and completely unexpectedly; the airplane veered sharply to the right and became uncontrollable with either the rudder or nose wheel and ran off the west side of the runway at an approximately 45 degree angle. The airplane continued to rotate to the right and traveled laterally approximately 35-45 FT across the grass and dirt adjacent to the runway until it came to a rest facing approximately 360 degrees (i.e. having rotated a full 180 degrees from initial point of touch down). There were no injuries and the engine was shut down and the aircraft was secured; later to be towed to the ramp. Initially I thought I had experienced an over-speed situation related to the prop governor. That was later ruled out. Later still; having observed several clear air vortices in the vicinity of the airport on the drive into town ('dust devils'); I speculated I may have encountered such a disturbance upon landing. The fact is that I do not know for sure what happened and why I lost control of the airplane. I have made hundreds of crosswind landings in this and other airplanes under similar or worse conditions as well as while flying Part 135 Grand Canyon tours. But from a human factors perspective with a view to avoiding future similar mishaps; my 'take away' opinion from this incident is; as they say; 'the flight isn't over until the airplane is shut down and secured on the ramp.' Again; I don't know for sure; but I may have simply became complacent in flying the same airplane into the same or similar airport environments such that a small cross wind gust may have unexpectedly caused the airplane to veer to the right (which would be consistent with a westerly cross wind hitting the vertical stabilizer and kicking the nose to the right); which I simply failed to anticipate and therefore correct prior to loss of control. But that would be precisely the point: accidents will happen when you least expect them; so be vigilante at all times.




Synopsis: A PA-32 pilot had a runway excursion after he lost control of his aircraft on landing for unknown reasons. No damage or injuries resulted.