On September 20, 1996, at 1840 central daylight time, a Saab 340B, N320AE, was undamaged during the passenger disembarking process at the Fort Smith Municipal Airport in Fort Smith, Arkansas. The two pilots, one flight attendant, and 23 passengers were not injured; however, one passenger was seriously injured. The airplane was registered to AMR Leasing Corporation and operated by Wings West Airlines, Inc., under Title 14 CFR Part 121. Visual meteorological conditions prevailed for the cross country flight which originated from Dallas-Fort Worth International Airport near Dallas, Texas, at 1721. An instrument flight plan was filed. According to a company representative, the airplane landed and parked at the passenger disembarking location at 1831. National Weather Services observation data indicates that a light rain begain falling at Fort Smith Municipal Airport at 1757 and was still falling as of their 1853 observation. According to a company representative, the flight attendant was at her post at the top of the stairs and she was helping passengers disembark. The fourth passenger to descend the stairs reported to the IIC that as he stepped on the second to the last stair he "slipped," immediately he dropped his briefcase, and "he reached for a handrail to support himself." The passenger reported that there was no handrail for him to hold on to and he subsequently fell to the pavement injuring himself. A company representative reported that there was a Ground Agent at the base of the stairs at the time of the fall, but that she did not see the "beginning of the fall" because "she was attending to another passenger at the time." The airplane's handrail extends down the stairs from the cabin door to the third step where it terminates (see enclosed photograph).