According to a survey by computing and disability charity AbilityNet, not one of the nine airline websites checked for accessibility using both manual methods and automated tools satisfied the criteria for facilitating access for visually impaired users, dyslexics and those unable to use a mouse.
The airlines surveyed - EasyJet, British Airways, Ryanair, BMI, British European, Monarch, Virgin Atlantic and Mytravelite - are preventing up to 15% of the UKpopulation from booking flights online and benefiting from the advantages that this offers in terms of price and availability, AbilityNet said.
With a potential market of 1.6 million registered blind users, and a further 3.4 million people with disabilities that prevent them using a standard keyboard, screen and mouse set-up, the airlines are missing out on their share of an overall annual spending power of £50bn to £60bn a year, the charity said.
Companies that fail to address accessibility issues also put themselves at risk of legal action, said Shuna Kennedy, chief executive at AbilityNet.
"From October 2004, when extensions to the Disability Discrimination Act come into force, websites will have to be accessible as a matter of law," she said.
EasyJet's website came out as the most accessible of the sites tested but, along with BA and Monarch Airlines, it could only manage a two-star rating on a five-star scale.
The remaining six airlines were given a one-star rating and were dubbed "very inaccessible" by AbilityNet. The Virgin Atlantic website was deemed to have "the most serious issues of accessibility of all those tested".
AbilityNet's report said much of the Virgin site's content and critical functionality is embedded in interactive presentations, so visitors to the site who cannot use a mouse, are vision impaired, or use speech output or voice recognition software would be unable to use the site at all.
Virgin Atlantic admitted it had problems on its site but said it was working to improve accessibility.