Many passengers experienced hour-long security queues from Friday night to Sunday, with some reporting that fellow travellers fainted and families were left in tears after missing flights.
Dozens of photos showed long queues stretching into the departures hall from security, with no social distancing in place.
A flurry of angry tweets slammed the airport for its “horrendous” organisation so close to the Christmas holidays.
“Absolutely horrendous #manchesterairport tonight. 3hrs in security, hundreds missing flights including us. People getting squashed in queues, people passing out,” wrote Claire Campbell.
“Staff present doing the best they could but fighting a losing battle. Managers, you should be ashamed of yourselves.”
“Manchester airport is currently the Hunger Games, avoid at all costs. Never seen anything like it,” tweeted Bethany F.
“Manchester Airport feels very much like everyone is trying to get the last chopper out of Plague Island before the borders are closed all around us – again,” wrote Jennifer Schmidt.
Many were flying home to see family for Christmas, some leaving early to get ahead of potential extra Covid-related restrictions that could be introduced in the next fortnight.
The airport’s Twitter account responded to several customers. saying: “We are aware security queues were longer than we would have hoped at times today and apologise for any inconvenience caused.
“We have seen a significant increase in passenger volumes which has put our operation under severe pressure.”
Ian Gold, en route to Spain, told the Daily Mail that he had started queuing at 12pm on Sunday and only made it through check-in and security at 3.45pm.
He said his flight had been delayed by an hour and 35 minutes due to the airport queues.
“Seven security gates are closed out of 10. That is infuriating, it really is,” said Mr Gold.
“Everyone is next to each other. There’s no air conditioning. It is scorching. I am furious about it.
“There are people in their 70s and 80s, they are literally trying to run to their planes.”
A spokesperson for Manchester Airport told The Independent: “We have, at times this weekend, experienced longer security queues than we would like.
“This is due to there being a greater number of passengers than expected, and a higher-than-usual rate of staff absence.
“Our customer service staff continue to do all they can to assist passengers. Wherever possible, travellers are being prioritised within the queue, but we are aware some people have unfortunately missed flights and, along with their airlines, we have been working to support their onward travels as best we can.
“Due to additional pre-departures checks, as countries update guidance for travel, it is very important that passengers arrive at least three hours before their scheduled flight time if they have to check in and drop bags.”