Passengers had to wait half an hour longer than the planned departure time on every flight from Birmingham Airport last year.
The West Midlands airport was the least punctual of all the travel hubs in the UK in 2022, according to analysis of Civil Aviation Authority.
That was more than twice as long as the previous year, when it was also ranked last for punctuality.
Delay times shot up between 2021 and 2022, with passengers having to wait four or five times longer last year than the year before on average.
Doncaster Sheffield - which closed in November - and Manchester airports had the joint second poorest punctuality records in 2022, with an average delay of 29 minutes.
They were followed by Luton (28 minutes), Gatwick (27 minutes) and Bristol (26 minutes) airports.
On the other side of things, East Midlands performed the best, with an average delay of 13 minutes.
Have you been caught up in airport chaos? Email webtravel@reachplc.com
May and June were the worst months for flight reliability in 2022, partly due to the aviation sector failing to recruit and train enough staff to cope with a surge in demand for holidays.
The average across all airports was 23 minutes. The analysis took into account all scheduled and chartered departures. Cancelled flights were not included.
When flights are significantly delayed, airlines are required under consumer laws to provide passengers with assistance, which can include refreshments, a means of communication and accommodation if required.
If the cause of disruption is under an airline's control, passengers are also due compensation of up to £520 depending on the length of the delay and the distance of the flight.
Some 10.3 million passengers travelled through Birmingham airport last year, making it the seventh busiest in the UK.
In addition to flight delays, many departing passengers were forced to spend several hours in long queues for check-in and security.
Around 50 airlines operate at the airport, such as Ryanair, Jet2.com, Tui Airways, Air France and Emirates.
A Birmingham airport spokesman said: "The start of 2022 was devastated by Covid.
"After travel restrictions were lifted, the aviation industry fought hard to recover.
"This year, the first since 2020 not impacted by Covid, our airport is running smoothly with customers set to equal or exceed pre-pandemic numbers.
"Customers using Birmingham airport this summer can expect changes to walking routes as we build our £40 million new security hall, set to be ready for June 2024."
CAA head of consumer Anna Bowles said: "Our data tells us that too many passengers faced disappointing levels of delays across UK airports last year.
"It is important consumers experience a high-quality service from both airlines and airports this year.
"We expect airlines to proactively provide passengers with information about their rights when flights are disrupted."
Airports are ordered from the longest average delay per departing flight to the shortest (duration in 2022 and 2021 brackets).
1. Birmingham (30 minutes; 12 minutes and 24 seconds)
=2. Manchester (29 minutes; nine minutes and 30 seconds)
=2. Doncaster Sheffield (29 minutes; 10 minutes and 18 seconds)
4. Luton (28 minutes; nine minutes and 42 seconds)
5. Gatwick (27 minutes; five minutes and 54 seconds)
6. Bristol (26 minutes; six minutes and six seconds)
=7. Cardiff (24 minutes; six minutes and 48 seconds)
=7. Edinburgh (24 minutes; seven minutes and 12 seconds)
9. Heathrow (22 minutes; 11 minutes and 48 seconds)
=10. Newcastle (21 minutes; seven minutes and 24 seconds)
=10. Isle of Man (21 minutes; NA)
=10. Aberdeen (21 minutes; 10 minutes and 36 seconds)
=13. Leeds Bradford (20 minutes; seven minutes and 42 seconds)
=13. Southend (20 minutes; two minutes and 48 seconds)
=15. Glasgow (19 minutes; eight minutes and 30 seconds)
=15. Stansted (19 minutes; six minutes)
=15. Southampton (19 minutes; 12 minutes)
=15. Bournemouth (19 minutes; seven minutes and 18 seconds)
=19. London City (17 minutes; six minutes and 12 seconds)
=19. Jersey (17 minutes; NA)
21. Belfast International (16 minutes; four minutes and 30 seconds)
=22. Liverpool John Lennon (15 minutes; seven minutes and six seconds)
=22. Belfast City (15 minutes; four minutes and 54 seconds)
=24. Exeter (14 minutes; 11 minutes and 12 seconds)
=24. Teesside (14 minutes; four minutes and 48 seconds)
26. East Midlands (13 minutes; six minutes)
