Weather and maintenance on Saturday led to crew scheduling issues, said Kate O'Malley with Frontier.
"It's frustrating, it's just that lack of control," said Amy Carrington, who was traveling with her months-old daughter Jane. Amy and her husband were excited to bring Jane to see family on Sunday afternoon - which is why they arrived plenty early for their flight on Sunday morning.
But their Frontier flight to Little Rock, Arkansas got canceled and they weren't sure what to do next.
So they went to the customer service line, only to wait.
"Wait in line for 30-40 minutes, doesn't
move, still no explanation," said Carrington, who spoke to 9NEWS even as the display on her phone showed that she had been holding with Frontier customer service for roughly 30 minutes.
A DIA spokesperson says that otherwise, flights appeared to be leaving on time on a very busy travel day. Many Frontier flights left on time on Sunday; but for the travelers affected by delays and cancellations, their worry centered on missing holiday plans.
"We apologize to our customers and are working to rebook passengers as quickly as we can," said O'Malley with Frontier.
Passengers can expect delays on Monday, Christmas Eve, as a result of winter weather and should check the status of their flight online before traveling, added O'Malley.
(KUSA-TV © 2012 Multimedia Holdings Corporation)