On February 11, 2017, about 1950 mountain standard time, Southwest Airlines flight 4152, a Boeing 737-700, N7822A, had a catering agent fall from the airplane while alongside provisioning the airplane. On board were the captain, first officer, three flight attendants and several passengers. The regularly scheduled passenger flight was operating under the provisions of 14 Code of Federal Regulations Part 121 from Phoenix Sky Harbor International Airport (PHX), Phoenix, Arizona, to Sacramento International Airport (SMF), Sacramento, California. According to Southwest Airlines, while passengers were boarding the airplane at the gate, a catering agent returned to the airplane to provide a box of peanuts. The agent stopped the provisioning truck short of the airplane creating a gap between the truck and the airplane. After entering the airplane to deliver the peanuts, the agent lost situational awareness and stepped backwards, falling through the gap, and suffered a fractured rib.