The watchdog has accused the architect of failing to properly assess the site before designing a new terminal building and extension to the existing runway at Romney Marsh.
Airport bosses are hoping to ramp up passenger numbers to 2 million by 2014, but the proposed new terminal will only handle around 500,000 travellers. Furthermore, work on the new terminal will only begin once the existing terminal is handling 200,000 passengers a year.
CABE fears passengers will not be 'delighted' by their experience at the newly expanded airport.
The watchdog said: 'In particular we are not persuaded by either the form or the relationship of the two proposed buildings. The alignment of the departure building is puzzling; there is no convincing logic for the disposition of the forms on the site.
'In addition it concerns us that the departure building has the appearance of a hangar and in no way addresses the landscape. A simpler linear arrangement that can provide ease of movement and separation of functions might be an option to consider.'
CABE has also raised the alarm at the project's impact on the environment. 'The expansion - raises many concerns about sustainability,' says the panel. 'We feel that greater thought needs to be given to this because of the considerable increase in intensity of use that is envisaged in terms of passenger throughput.'