A Flybe pilot from Devon has been arrested on suspicion of being over the alcohol limit while preparing to fly.
The 48-year-old pilot from Crediton was due to fly from Newquay Airport in Cornwall to London Gatwick on Wednesday morning when he was held.
The flight was then cancelled and passengers faced delays of up to five hours, with some missing connections.
The man has yet to be charged and was later released on police bail until December 8.
A Flybe spokesman said: "Flybe can confirm that one of its pilots volunteered to help the police with their inquiries at Newquay Airport yesterday.
"The airline is not able to comment further while the police investigation is taking place."
The alcohol limit for pilots, air crew and air traffic controllers is 20mg per 100ml of blood. The drink drive limit in the UK for motorists is 80mg per 100ml of blood.
Fog is affecting flights to and from the West Country. Passengers are being advised to check in as normal.
LANDS END AIRPORT All flights are currently on hold.
EXETER AIRPORT Skybus flights to and from the Isles of Scilly are currently on hold.
NEWQUAY AIRPORT Skybus flights to and from the Isles of Scilly are currently on hold.
Last winter's storms could be behind a big rise in passenger numbers at Newquay Airport.
Nearly 80,000 people used it between January and May, that's up 30% on last year's figures. It's thought the rail problems at Dawlish were a factor in people turning to air travel.
Mascots from Cornwall's tourist attractions will protest at Newquay Airport today, to try and promote the county's tourism industry. Mascots from Flambards Theme Park and the Cornwall Seal Sanctuary are trying to spread the message that Cornwall is 'Open for Fun'.
Flights into and out of Exeter and Newquay airports are subject to delay caused by problems at the national air traffic control centre in Hampshire. But the disruption is not as great as that being experienced at major terminals including Heathrow, Gatwick and Stansted.
At Exeter, a flight from Belfast due to land at 0820 is not expected until 1030. The Paris departure scheduled for 0845 is now not expected to leave until 1130. The service to Amsterdam which was due to take off at 1015 is now due to leave at 1105.
At Newquay, there are delays to services to and from Gatwick. But both Newquay and Exeter are advising passengers to check in as normal.
The airline Flybe is expected to agree a deal with Newquay Airport today which will see it continuing to operate flights to London Gatwick until 25 October 2014 - Cornwall's only air link to the capital.
Meanwhile, Cornwall Council is applying for government funding to preserve the route after that date.
Business leaders in Cornwall are considering the impact of plans to cut the county's only air link to London.
Flights from Newquay to Gatwick are currently run by Exeter-based Flybe. But Easyjet has bought its landing slots, and has decided against continuing the route after next March.
Flights from Cornwall to London Gatwick will end early next year.
Easyjet bought the landing slots from Exeter based Flybe, but now say there isn't enough demand to keep the service open.
It's a major blow for the airport at Newquay, but also for the county's business community who'll have to travel to the capital by train or road.
The nearest airport to London from Newquay will be Southend.
Our Cornwall correspondent Steve Hardy reports.
Flybe has said it regrets the inconvenience experienced by its passengers following the landing of flight BE806:
A plane landed safely at Newquay Airport in Cornwall last night, after the pilot reported a hydraulic fuel leak.
All passengers disembarked safely from the London Gatwick flight, and there are no reports of any injuries.
Cornwall Fire and Rescue Service was mobilised to the scene at around 9:30pm but the incident had already been dealt with by the airport fire service.