The current runway would be lengthened by 590 metres, stretching closer to Belfast Lough, if plans were given the go ahead.
Chief Executive Brian Ambrose said the redevelopment would mean the airport could offer longer haul flights from the city, to more European destinations.
However, Mr Ambrose said opening hours would not change as a result, nor would the number of departures from the airport.
He said: "A longer runway will allow a longer take-off and landing distance that will facilitate aircraft to carry full fuel loads and maximum passenger numbers, which at present is not possible.
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"We have made no secret of our ambitions to fly to a select number of European destinations, which, if the runway is extended, will undoubtedly improve customer choice and value," he said.
"We would like to make it clear that we have no intention of introducing 'wide-bodied' aircraft to our airport.
"Thus the size of the aircraft currently using the airport will not increase," the airport boss told the BBC.
However, Belfast City Airport Watch (BCAW) has slammed the plans, which it said would created an "irreversible nightmare" for east and south Belfast.
The groups Fiona McKinlay said: "The runway extension will enable airlines to fly aircraft with heavier fuel loads - that means jets will be noisier and will fly lower,
"Whatever assurances the airport may provide, the fact remains that there's nothing to stop airlines using big jets on all 48,000 of its permitted annual flights," Ms McKinlay told the BBC.
She called in on the Environment Minister to look into the plans as part of a public enquiry.
(PR/JM)
