Mel was present at CTU throughout the events of the first half of the day.
Mel was present when George Mason called all department heads over for an emergency briefing regarding the nuclear bomb threat. ("8:00am-9:00am").
After surviving the bombing at CTU that morning, she worked alongside Michelle Dessler and other staffers throughout the course of the day.
Background information and notes
Mel's name is not spoken in the episodes in which she appears; however, she is identified as Mel in a scene deleted from Day 2: 8:00pm-9:00pm in which she was asked by Michelle Dessler to contact Flights 12, 16 and 20 in order to reroute them from Norton Airfield.