A national trend of airlines adding bigger aircraft and red-eye flights over the holidays prompted long security waits for passengers at Denver International Airport as screeners struggled to keep up.
Transportation Security Administration spokesman Nico Melendez said his agency was not prepared for the number of flights at the airport late Saturday and early Sunday because the airlines had failed to communicate their needs.
Only one checkpoint was open when there probably should have been three, he said.
"There was some 64 flights that had been added in the late hours of the evening that we had no knowledge about," Melendez said.
Airlines made the flight shifts through the Christmas weekend in order to avoid delays during one of the busiest travel periods of the year. The Associated Press reported operators expect about 38 million passengers over a 17-day period spanning Christmas and New Year's.
"Not sure if this is TSA or (the airport's) fault but I'm in LONGEST security line at 12 a.m.," one woman traveling through DIA posted on Twitter early Sunday. "Only one lane open at ONE checkpoint?! HUGE FAIL."
"Thanks for being prepared for the post-Christmas rush with only two TSA AGENTS," another said in a pre-dawn Sunday rant. "Loved standing in a two (hour) line and missing my flight."
Melendez said TSA is making adjustments over the next few days to prepare for the expected influx of passengers to avoid problems.
Airport officials say travelers might want to arrive earlier than the normally suggested two hours before their flight just to ensure smooth sailing to the gate.
"We don't necessarily add staff, but we'll adjust our staffing to make sure we have the people in place," Melendez said. "We staff to the demand of the flights. We don't have a stockpile of employees sitting and waiting to go to Denver."
Weather-related cancellations and sporadic delays also plagued travelers at DIA on Monday.
DIA spokesman Heath Montgomery said at least 11 flights were axed because of bad weather in Texas. He said other flights were likely delayed due to storms interrupting operations Minneapolis-St. Paul International Airport and Chicago's O'Hare International Airport.
Southwest Airlines and United Airlines were offering to change the itineraries of passengers passing through some airports in the Midwest because of the storms.
DIA estimates it had its seventh busiest day ever on Sunday with 175,000 passengers. This coming Sunday is expected to be the second busiest ever with almost 179,000 travelers.
On Monday, about 166,000 people were expected to pass through the airport, well over the 145,000 counted on a typically day.