A Flybe pilot was arrested moments before he was due to fly on suspicion of drink-driving.
The pilot had been due to fly from Newquay Airport in Cornwall to London Gatwick on Wednesday morning when he was removed and taken for a breath test.
A police source told the BBC officers were alerted following concerns from a fellow crew member.
The flight was then cancelled and passengers faced delays, with some missing connections.
A passenger on board the flight, who did not want to be named, said: "We all got on the plane and then there was an announcement. We were told the pilot was unwell."
A Devon and Cornwall Police spokesman confirmed a 48-year-old man from Crediton was arrested on suspicion of being over the drink-drive limit.
"He was taken to Newquay police station. He has been released on police bail until 8 December," the spokesperson said.
A Flybe spokesman said: "Flybe can confirm that one of its pilots volunteered to help the police with their inquiries at Newquay Airport.
"The airline is not able to comment further while the police investigation is taking place."
For pilots, air crew and air traffic controllers the alcohol limit is 20mg per 100ml of blood. The drink drive limit in the UK for motorists is 80mg per 100ml of blood.Reuse content