On May 4, 1997, approximately 1325 mountain daylight time, a cabin crew member aboard a parked Boeing 737-201, N217US, was seriously injured when he fell from the aircraft. The airplane was not damaged and there were no injuries to the two cockpit crew members, two other cabin crew members, and 92 passengers. Visual meteorological conditions existed, and an IFR flight plan had been filed. According to the accident report submitted by Frontier Airlines, Inc., the airplane was operating as flight 128, scheduled domestic passenger service to Minneapolis, Minnesota. The airplane was ready for pushback from gate A-36 when the "B" flight attendant told the "A" flight attendant that a thru passenger had reported that the cabin cleaning crew had mistakenly removed his child's stuffed animal and that he wanted it returned. The "A" attendant opened the forward entry door after the jetway had backed away from the airplane. Either losing his balance or not realizing the jetway had backed away, he fell 8 feet, 3 inches to the tarmac below. His injuries consisted of two fractured wrists, a fractured jaw, and a concussion. Both "B" and "C" flight attendants witnessed the accident. According to Frontier Airlines chief flight attendant, flight attendants are thoroughly trained on procedures for opening cabin entry doors. First, the flight attendant disables the emergency evacuation slide system, then peers through the door's porthole to make sure the jetway or stairs are in place. Next, the station makes a coded knock on the door. The cabin attendant then "cracks" the door before opening it completely. She said the injured flight attendant violated company policy and procedures that resulted in the accident.