Tired pilots are putting passengers at risk because airlines aren't taking fatigue seriously, a new report claims.
In a survey of 7,200 pilots across Europe 58 per cent of them said they thought their pilot colleagues were sleepy at work and half said that tiredness was not taken seriously by their company, the Daily Mail reported.
More than a quarter felt their airline was understaffed and 14 per cent even admitted to working when they were unwell.
The research, by the London School of Economics, also found that employees felt unable to raise concerns for fear they would be treated as a troublemaker.
The British Airline Pilots' Association has said it's not surprised by the findings and said fatigue is always top of their members' concerns across all types of airlines.
Head of Flight Safety at the British Airline Pilots' Association (Balpa), Dr Rob Hunter, said: "It's not surprising to Balpa that the LSE survey shows more than 50 per cent of pilots feel fatigue is not being taken seriously by their company."
The association has previously said that pilots are being forced to work shifts of more than 20 hours without breaks.
The study found that the problem was particularly rife on budget airlines where crew are expected to work multiple flights on the same day.
"Fatigue has been a growing issue among pilots and has intensified since the introduction of EASA flight time limitations earlier this year," Dr Hunter added.
"Balpa has been challenging all airlines and carriers to improve their fatigue management.
"Our own survey with in collaboration with the CAA previously highlighted similar issues, with pilots not having confidence in their companies' attitudes towards fatigue or reporting of fatigue.
"Safety is the top priority for pilots, as is demonstrated in the LSE's survey, with 93 per cent agreeing their colleagues take safety seriously.
"We welcome further research into safety culture, an important area that is often ignored, and hope that this latest survey will shine some light on the issues faced by today's pilots."
A serving airline captain, speaking anonymously, told MailOnline Travel: "The alignment of pilots' flying hour limits by the EU was opposed by the pilot associations in each country but was of course backed by the airlines who got what they wanted - a lowest common denominator solution meaning longer duty hours for crews and lower costs.
"Fatigue, both short term and long term, is now a significant factor for pilots, especially those working for the low cost carriers who will routinely roster their crews right up to the new higher EU limits.
"Sadly it is only a matter of time before an incident or accident by an EU carrier is attributed to fatigue in the same way that fatigue and crew rostering issues were highlighted in the Colgan Air crash in Buffalo, USA, in which 50 people lost their lives.'"
Dr Tom Reader, Associate Professor in Organisational and Social Psychology at LSE and one of the report's co-authors, said: "Pilots, airlines, and regulators need to begin a dialogue to understand what these results means for the industry.
"This will help to address the concerns raised by pilots, and help to identify what could be changed to maintain the positive safety culture within the industry, while ensuring that European aviation remains competitive."
The survey found that Britain performed third worst in Europe with pilots rating their airline's approach to fatigue lower than in any other country apart from Croatia and Luxembourg.
But Tim Alderslade, chief executive of Airlines UK, said: "Safety is the number one priority for everyone involved in aviation.
"The long-term data shows that air travel is getting safer - and a strict adherence to global standards across the industry demonstrates a commitment to ensuring that this trend continues."
24 HOURS OF FATIGUE
How a pilot can end up working around the clock while still observing the safety rules:
A pilot wakes at 7.30am and starts stand-by duty at 12 noon. The pilot is called at 3.30pm to report for duty at 5pm.
His flying duty finishes with him landing at 4am the following morning, by which time he has been awake for more than 20 hours.
A pilot in this situation would experience severe sleepiness similar to having a blood alcohol level more than three times the legal limit for flying.