LGT TAXIING TO PARKING AT NIGHT IN AREA OF PARKED ACFT HAS WINGTIP CONTACT PORTABLE STAIRS.

Narrative

AT OKC; WILL ROGERS ARPT; AT NIGHT; ACR ROUTINELY PARKS ACFT AWAY FROM THE TERMINAL ON THE RAMP. THIS SUMMER; MUCH CONSTRUCTION IS BEING DONE ON TAXIWAYS; RWYS; AND RAMPS SO TAXIING AROUND AT NIGHT CAN BE EXTREMELY DIFFICULT. ON THE NIGHT OF AUG 1992; I WAS A FO ON AN LGT FLT THAT LANDED AT OKC. UPON ENTERING THE RAMP WE STRUCK A PORTABLE METAL (SEE-THROUGH) SET OF STAIRS USED BY ACR'S FLEET SVC TO ENTER THEIR ACFT AND CLEAN; ETC. WE WERE NEVER ADVISED OF AN ACFT PARKED ON THE RAMP (WITH GND EQUIP) WHICH WAS BTWN US AND THE ONLY TAXI RTE TO OUR GATE. WE NEVER SAW THE STAIRS. WERE UNAWARE THAT WE HAD STRUCK THEM. WE PARKED AT OUR GATE; COMPLETED THE 'SECURE' CHKLIST; AND WENT TO OUR LAYOVER HOTEL. IF IT HAD NOT BEEN FOR OUR NIGHT CLEANER NOTICING OUR WINGTIP; IT MIGHT NOT HAVE BEEN FOUND UNTIL THE MORNING PREFLT. THE ONLY DAMAGE WAS TO THE 'NAV' LIGHT AND WINGTIP. IF ACFT ARE GOING TO BE PARKED 'OFF' GATES ON RAMPS; GND CTL SHOULD NOTIFY OTHER TAXIING ACFT. BETTER LIGHTING OF THE PARKED ACFT AND EQUIP MUST BE UTILIZED! SUPPLEMENTAL INFO FROM ACN 218289: A FEW HRS LATER; MY FO AND I WERE CALLED ON TELEPHONE BY A FLT MGR; STATING THAT L WING NAV LIGHT LENS WAS BROKEN; IT WAS BELIEVED THAT A TUBULAR PORTABLE STAIR ASSEMBLY NEAR ACR ACFT HAD BEEN CONTACTED BY OUR WINGTIP. NOTHING WAS FELT OR KNOWN BY MY CREW OR PAX TO CONFIRM THIS.