The airport's owner wants to see a huge increase in passenger numbers
Green campaigners have said plans to expand a Kent airport to handle up to six million passengers a year by 2033 are "flights of fancy".
Kent Green Party has delivered a critical submission in response to Kent International Airport's plans.
The Campaign to Protect Rural England (CPRE) has also said the plans, revealed on 8 October, are unrealistic.
Airport owner Infratil said it expected passenger numbers to grow as London airports became more congested.
The airport at Manston, taken over by Infratil three years ago, currently handles 16,000 travellers a year.
In its draft master plan for the next 25 years, the company said it hoped one million passengers would be using the site each year by 2011.
It also expected freight carried through the airport, at Manston, to rise from 33,000 tonnes to 500,000 tonnes.
It claimed that employment generated by the airport would be over 3,500 jobs in 2018 and 7,500 jobs in 2033.
A public consultation period ended on 19 December, with the final version of the master plan due to be published early next year.
The Green Party said the master plan took no account of the contraction in the civil aviation industry in recent months.
"Coupled with the current recession which is already beginning to reduce the number of flights being taken, plans for Manston Airport to expand are literally 'flights of fancy'," said spokesman Steve Dawe.
The party has called for "more realistic" leisure and agricultural uses for the site, including providing more allotments.
CPRE Kent said the airport plan fell far short of the mark.
"The master plan is full of aspirations, but is very light on justification," said spokesman Chris Lowe.
"It is impossible to see what the impacts of such major growth will be - not only on Thanet, but on Kent and beyond - as the necessary supporting work has not been done.
"As it stands, the master plan raises more questions than providing answers."