London (CNN)UK airline Flybe said it was sorry on Wednesday to passengers affected by flight cancellations.
In a statement, the airline said it "sincerely apologizes" to affected passengers, although 95% of flights are operating as normal.
Passenger Alan Williamson told CNN that he was meant to fly from East Midlands Airport to Glasgow International at 12.20 p.m. local time.
While checking in Tuesday afternoon, Williamson noticed that the system said the flight had already departed, so he tweeted Flybe.
"They responded this morning and advised me that the flight was canceled," Williamson told CNN.
"I had no other communication and was already on a shuttle bus to the airport."
He then rebooked with Flybe to fly Wednesday evening ahead of a business meeting Thursday.
"I was able to check in but it's showing as 'the flight has already flown,'" he said, adding: "I'm predicting that tonight's flight will be canceled too."
Williamson called the lack of communication from Flybe a "bit of a joke."
The airline blamed an industry-wide shortage of pilots, Easter holidays and base restructuring for the cancellations.
"We have already identified several mitigation actions and will be issuing further updates throughout the day," reads the statement.
"All those affected have been emailed and advised they can re-book for travel on an alternative flight or apply for a full refund."
Ten Flybe flights serving Belfast City Airport were canceled and Birmingham, Leeds Bradford, Aberdeen and East Midlands were also affected, according to the UK's Press Association news agency.
Flybe is an independent regional airline based in Exeter, England, which operates more than 158,000 flights a year.
It carries 8 million passengers a year on 210 routes across 15 countries.