MD80 CREW CONTINUED TO THEIR DEST ARPT AFTER THE CREW WAS UNABLE TO RETRACT THE LNDG GEAR.

Narrative

FLT DEPARTED ON TIME. IT WAS THE FO'S LEG. THE GEAR DID NOT RETRACT. WE AGREED ON 210 KIAS AND INFORMED HOUSTON DEP. FO FLEW THE ACFT AND I RAN THE CHKLIST. ON PLACING THE GEAR LEVER DOWN; ALL 3 GEAR LIGHTS WERE INSTANTLY GREEN. I DID NOT NOTICE THE STATUS OF THE GEAR DOOR OPEN LIGHT. HOWEVER; THE FO IS CERTAIN THAT IT WAS ILLUMINATED ON FINAL AT DEST; SO IT IS LIKELY THAT IT WAS LIT UP. AT THIS POINT; I FELT THAT THE GEAR ISSUE WAS COMPLETE -- IT WOULD REMAIN DOWN. THE DEST ISSUE WAS THE NEXT TASK. THE FORECAST WAS ABOVE 1/2 MI. I CONTACTED DISPATCH. A NEW RELEASE GEAR EXTENDED WAS ACCOMPLISHED WITH AN ALTERNATE INSTEAD OF THE ORIGINAL. I INFORMED THE PAX OF OUR STATUS AND MY INTENTIONS. THE WX AT DEST DETERIORATED; WHICH NECESSITATED FURTHER RESEARCH DUE TO MY BEING ON HIGH MINIMUMS CAPT STATUS. WE FLEW A CAT APCH TO AN AUTOLAND ON RWY; LNDG WITH 8600 LBS OF FUEL. I'M NOT SURE WHERE WE CLRED THE RWY. ANOTHER ACFT CALLED OUT THAT WE HAD A GEAR DOOR OPEN. THE FO REPLIED QUICKLY; 'WE KNOW.' I THOUGHT AT THE TIME THE OTHER ACFT DIDN'T SAY DRAGGING AND WE HAVE NORMAL HYDS. AT THIS POINT; WE WERE APCHING THE TURN-IN TO THE GATE. AFTER DEPLANING; I LOOKED AND SAW THE GEAR DOOR ON THE GND. I ASKED A FLT ATTENDANT WHETHER HE HAD HEARD THE SCRAPING AND HE SAID 'SURE; I WAS THINKING OF CALLING YOU.' THE TRAINING WAS ADEQUATE. I WAS AWARE THAT A DRAGGING GEAR DOOR REQUIRES MODERATE BRAKING AND A STOP STRAIGHT AHEAD UNTIL MAINT CAN PIN THE GEAR AND STOW THE DOORS. THE FACT THAT AN ADDITIONAL PROC WAS REQUIRED WAS NOT CLR TO ME AT THE TIME I WAS RUNNING THE RED GEAR LIGHT INFLT WITH GEAR HANDLE UP; GEAR DOOR OPEN LIGHT WITH L NOSE; R GEAR LIGHTS GREEN. FO AND DISPATCH BOTH PERFORMED WELL.