Coventry Airport's plans for a "swanky new terminal" to be used by just one peak-time morning flight have been condemned by its Birmingham rival as unrealistic.
The resumption of a public inquiry yesterday heard Birmingham International Airport lawyers claim that the proposed expansion at Coventry would lead to increased air traffic and flight delays.
But fears about increased safety risks caused by the growth in air traffic above the West Midlands were dismissed by the Civil Aviation Authority which said they could be overcome if the two rivals worked together.
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The inquiry, at Leamington Town Hall, is considering Coventry's plans for a permanent terminal at the airport - now called West Midlands International Airport (WMIA) - capable of handling two million passengers a year.
BIA opposes planning permission for the terminal, at Baginton, because of fears it will hinder its own plans for a second runway.
John Steel, QC, for BIA, told the inquiry inspector Neil Roberts that both airports had been asked to provide a model showing possible scenarios for sharing airspace in the future. Currently, BIA's single runway caters on average for 40 aircraft an hour.
He accused WMIA of providing an incorrect model as it claimed it would only see one flight depart during the busiest time of the day, from 7am to 9am.
"What is being modelled is one departure at 7am," he said.
"Now we believe that is unrealistic and we believe that evidence has been given to us, that the airport is not looking to stay there with a swanky new terminal and have no movements in the busiest part of the morning."
According to a BIA-commissioned report by the National Air Transport Service, and based on predicted WMIA growth by 2014, Coventry's expansion would lead to delays of up to 2.3 minutes per flight at BIA peak times.
A report by Philip Roberts, the assistant director of air space policy for the Civil Aviation Authority's Directorate of Airspace Policy, said it was possible for both airports to share the same airspace safely.
It said: "The CAA considers that, based on the results of the simulations conducted and the material produced by both BIA and WMIA, the airspace in the Midlands area can safely accommodate operations from both BIA and WMIA up to the two million passengers per annum anticipated as a result of the planning application under consideration by the inspector."
To ensure such levels of safety, the CAA said any delay would be manageable if the two airports worked together to introduce changes, for example scheduling changes or by reducing the time delay between flight take-off from five nautical miles to three.
This would mean the time delay between two flights taking off would be reduced in line with aviation standards.
In its opening submission, Coventry said BIA's objections were "misconceived and threadbare, exposing the naked commercialism beneath".