An internal investigation has been launched at Gloucestershire Airport after allegations of bullying and the "terrifying" condition of a runway.
Concerns have been raised in an anonymous letter sent to councillors and members of the airport's board.
The letter criticises the way managing director Mark Ryan, who has since stepped down, treated staff.
Gloucestershire Airport confirmed two out of its three runways had been out of service since October.
The letter raises concerns about operations at the site, adding that staff felt "bullied" and were "scared to speak out" about issues and about losing their jobs.
It also alleges that one of the airport runways had been in a "disgusting" state for a long time, "with little done to fix it".
Cheltenham Borough Council and Gloucester City Council jointly own the airport, which is internally investigating the claims made in the letter.
Jon Topping, head of policy and resources at Gloucester City Council, said: "I can confirm that we have been made aware that an anonymous letter was sent to the directors of Gloucestershire Airport Limited (GAL).
"The chairman of GAL has given assurances to the shareholders that GAL will be treating it in accordance with their internal procedures and the council will therefore not be making any further public comment until that process has been concluded."
The Civil Aviation Authority, which oversees and regulates all aspects of aviation in the UK, said it was informed last week that Mr Ryan was being replaced, but believed it to be a temporary measure.
The BBC has been unable to get a response from Mr Ryan.