Flight assembly Trolleys from the tray assembly area, bonded store, and equipment stores are then moved into the flight assembly area, where all of the trolleys for a specific flight are marshalled. The contents of trolleys are checked by inspectors against the inventory of the flight. Food trolleys may be packed with dry ice in order to maintain a chilled temperature. In some cases, trolleys now have electric units to keep them chilled. These must be plugged in during this