
Travellers said the result was chaos. Some reported vomiting and fainting while waiting to pass through checks, with queues reportedly stretching for hours during peak periods.
Staffordshire resident Carol Boon, who had been on a hen do in Milan, said: "It was just horrible." She described scenes of confusion and distress as passengers tried to make their flights.
Ms Boon explained: "Even if we were there five hours early, we weren't told the gate number until about 90 minutes before. There was nothing we could have done."
Max Hume, 56, from Leeds, said: "It was just awful -- just a mess." He ended up spending £1,800 on alternative travel via Luxembourg after missing the flight.
Mr Hume said easyJet offered him a seat on a later flight days away but said he needed to get home sooner.
He added the airline initially offered £19 compensation and a Thursday departure, which he said was unworkable: "We would have had to pay £300 on top."
According to industry bodies ACI Europe and Airlines for Europe (A4E), early implementation of the system has led to severe disruption across multiple airports, with waiting times of two to three hours at peak times.
In one reported case, no passengers had reached a departure gate by the scheduled closing time, and only 12 had arrived 90 minutes later, highlighting the scale of the delays.
The BBC has been told that until last week border authorities could fully suspend the system when queues became excessive, but now only partial suspension is allowed, limiting flexibility during disruption.
Airlines and airports have warned the current rollout risks widespread operational strain ahead of the busy summer season unless procedures are adjusted.
Another passenger, Joy Oliver, said: "It was absolute carnage." She arrived three hours before departure but still faced hours in queues. She has since rebooked and is attempting to get home via Edinburgh.
Adam Hoijard, from the Wirral, said he and his family also arrived early but still missed the flight after being stuck in queues for hours. He said his five-year-old son had been left "crying in bed" after the ordeal. The family have since spent around £1,000 booking alternative flights.
Rejecting suggestions that passengers simply did not allow enough time, Hoijard said: "How much time can you leave to wait in a queue and be told to wait?"
Greater Manchester travel agent Laura Featonby said: "Biometric checks inevitably slow down border movement." She said passenger data is stored for several years and rechecked on exit, increasing processing demands.
Featonby added that the situation in Milan may have been worsened by passengers arriving before the full transition into the new system, creating additional bottlenecks for border staff.
Express.co.uk has contacted easyJet for comment.