Narrative:

Flight was normal in all respects till touchdown. It was night and the runway was wet, but it was not raining. Touch downed on touchdown zone on centerline, on speed, with normal rate of descent. When thrust reversers deployed, the nose of the aircraft rapidly veered about 20 degrees left. I immediately pushed the reverse thrust levers to reverse idle, added right rudder and expected the nose to move back to the right. It did not. I felt as if I was skidding and thus was very cautious about overcorrecting and making a bad situation worse. I increased right rudder smoothly. All I could see was the runway edge lights and I knew I was going to stay on the runway side of them. For a brief period, I felt a vibration and wondered if it was the shoulder of the runway or not. Once back on centerline, I rolled to the end and cleared the runway. Everything looked and felt normal, so we taxied to the gate. Wanting to know for sure if I went off the runway, I did a postflt inspection and saw the grass and mud. I had exited the runway when the visual cues available had indicated that I had not. I believe runway edge lights should be at the runway edge of concrete or not so named. I can't say why the nose veered in the first place. It may be due to the aircraft, ie, uneven main struts, unusually easy to use reverse levers that worked way too well and brought on too much power too soon, or me being impatient and not waiting for the nosewheel strut to compress and definitely have weight on it, etc. Whatever the reason initially, it should not have been enough to exit the runway. However, the wet runway added to the problem. I believe the rapid yaw caused a hydroplane effect which helped delay the onset of recovery. I felt like I was skidding and that I needed to be careful not to over-control the recovery and make a bad situation worse. As I eased the nose around smoothly, I used up more of the width of the runway, but I could see the 'runway edge' lights and was not worried. I may have used it all (the width) up, but I was going to be able to safely return the aircraft to the centerline without getting sideways in the other direction, and I was going to keep it on the runway. Little did I know that the runway edge lights were not on the runway edge but some 6 ft outside. I could not see this on a dark night with a wet runway without the opportunity to stop and take my time to see it. The lights were not what I thought they were. I was visually deceived.

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Original NASA ASRS Text

Title: MD83 FLC HAS RWY EXCURSION DURING LNDG ROLL.

Narrative: FLT WAS NORMAL IN ALL RESPECTS TILL TOUCHDOWN. IT WAS NIGHT AND THE RWY WAS WET, BUT IT WAS NOT RAINING. TOUCH DOWNED ON TOUCHDOWN ZONE ON CTRLINE, ON SPD, WITH NORMAL RATE OF DSCNT. WHEN THRUST REVERSERS DEPLOYED, THE NOSE OF THE ACFT RAPIDLY VEERED ABOUT 20 DEGS L. I IMMEDIATELY PUSHED THE REVERSE THRUST LEVERS TO REVERSE IDLE, ADDED R RUDDER AND EXPECTED THE NOSE TO MOVE BACK TO THE R. IT DID NOT. I FELT AS IF I WAS SKIDDING AND THUS WAS VERY CAUTIOUS ABOUT OVERCORRECTING AND MAKING A BAD SIT WORSE. I INCREASED R RUDDER SMOOTHLY. ALL I COULD SEE WAS THE RWY EDGE LIGHTS AND I KNEW I WAS GOING TO STAY ON THE RWY SIDE OF THEM. FOR A BRIEF PERIOD, I FELT A VIBRATION AND WONDERED IF IT WAS THE SHOULDER OF THE RWY OR NOT. ONCE BACK ON CTRLINE, I ROLLED TO THE END AND CLRED THE RWY. EVERYTHING LOOKED AND FELT NORMAL, SO WE TAXIED TO THE GATE. WANTING TO KNOW FOR SURE IF I WENT OFF THE RWY, I DID A POSTFLT INSPECTION AND SAW THE GRASS AND MUD. I HAD EXITED THE RWY WHEN THE VISUAL CUES AVAILABLE HAD INDICATED THAT I HAD NOT. I BELIEVE RWY EDGE LIGHTS SHOULD BE AT THE RWY EDGE OF CONCRETE OR NOT SO NAMED. I CAN'T SAY WHY THE NOSE VEERED IN THE FIRST PLACE. IT MAY BE DUE TO THE ACFT, IE, UNEVEN MAIN STRUTS, UNUSUALLY EASY TO USE REVERSE LEVERS THAT WORKED WAY TOO WELL AND BROUGHT ON TOO MUCH PWR TOO SOON, OR ME BEING IMPATIENT AND NOT WAITING FOR THE NOSEWHEEL STRUT TO COMPRESS AND DEFINITELY HAVE WT ON IT, ETC. WHATEVER THE REASON INITIALLY, IT SHOULD NOT HAVE BEEN ENOUGH TO EXIT THE RWY. HOWEVER, THE WET RWY ADDED TO THE PROB. I BELIEVE THE RAPID YAW CAUSED A HYDROPLANE EFFECT WHICH HELPED DELAY THE ONSET OF RECOVERY. I FELT LIKE I WAS SKIDDING AND THAT I NEEDED TO BE CAREFUL NOT TO OVER-CONTROL THE RECOVERY AND MAKE A BAD SIT WORSE. AS I EASED THE NOSE AROUND SMOOTHLY, I USED UP MORE OF THE WIDTH OF THE RWY, BUT I COULD SEE THE 'RWY EDGE' LIGHTS AND WAS NOT WORRIED. I MAY HAVE USED IT ALL (THE WIDTH) UP, BUT I WAS GOING TO BE ABLE TO SAFELY RETURN THE ACFT TO THE CTRLINE WITHOUT GETTING SIDEWAYS IN THE OTHER DIRECTION, AND I WAS GOING TO KEEP IT ON THE RWY. LITTLE DID I KNOW THAT THE RWY EDGE LIGHTS WERE NOT ON THE RWY EDGE BUT SOME 6 FT OUTSIDE. I COULD NOT SEE THIS ON A DARK NIGHT WITH A WET RWY WITHOUT THE OPPORTUNITY TO STOP AND TAKE MY TIME TO SEE IT. THE LIGHTS WERE NOT WHAT I THOUGHT THEY WERE. I WAS VISUALLY DECEIVED.

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.