The aircraft was parked parallel to the terminal building at Exeter Airport, about 65 metres behind a Fokker F-27. Both aircraft were facing southwest; the BAe 146 was about one metre to the right of the yellow taxiway line and the F-27 about one metre to the left. The passengers had disembarked from the BAe146 and only the operating crew and ground handling personnel were on board. One of the latter, a member of the airport catering staff, had just delivered some supplies. She left the aircraft through the front passenger door, and had both feet on the top section of the aircraft steps,when the F-27 started to taxi forward; at this point the bottom of the steps started to move rearwards in an arc centred on the rear top corner which was against the fuselage. She fell backwards, from a height of about 2 metres, onto the ground below and sustained serious injury to her back, ribs and head. The steps continued rearwards scraping along the fuselage and came to rest against the left main landing gear.