[PHXFlyer]

From the Allegiant Air website:

• What time should I arrive at the airport for my flight?
• Allegiant Air recommends arriving at the airport at least two (2) hours prior to scheduled departure. Customers need to be checked in no less than 45 minutes prior to scheduled departure which is when the Ticket Counter closes.

Your timeline seems to be a bit off. You said your daughter sent you a text message @3:20. You then said they inched through the line for an hour or so and at that point the lights at the counter were turned off. The scheduled departure of the flight was 5:15 so the ticket counter would have closed @4:30 and anyone not checked in at that point would be considered a no-show. Was she in line at 3:20 or just arriving at the airport? It seems that 10 minute discrepency could be crucial here.

You go on to say that your daughter called you at 5:13 which is 2 minutes before the scheduled departure. It is perfectly reasonable to conclude that the person working the counter shut it down @4:30, went to the gate to board the plane, probably got the plane boarded and the door shut a few minutes early (the 5:27 PM departure time you saw was wheels-up time) and was back at the counter at 5:10 or so to deal with those, including your daughter, who did not make the cutoff time.

People miss flights all the time. Unfortunately the Allegiant flight from St Petersburg-Clearwater to Lexington is the only flight. Allegiant doesn't interlinewith any other airline. Your options when a flight is missed are severly limited.