The Defence Department is considering letting airlines use RAAF Base Pearce at Bullsbrook as an alternative airport to Perth to ease midweek congestion.
Sources in Sydney and Canberra say senior executives of at least two Perth Airport-based airlines visited Pearce late last year to inspect the base's facilities.
Perth Airport is overstretched with almost 70 per cent of its landing slots filled.
At critical times - between 5am and 9pm from Tuesday to Thursday - there are no free landing slots or very few.
But a Defence spokesman denied the report, saying there were no plans to turn Pearce into a commercial airport.
One airline executive told _The West Australian _the Pearce option "was very interesting because of its proximity to the northern suburbs".
Another said the proposal was fascinating because of congestion at Perth Airport.
Perth Airport is currently working with Qantas and Virgin Australia - its two biggest customers - on a business plan for a second parallel runway.
The airport has two runways but they cross and cannot be used concurrently, only alternatively and then only in certain wind conditions.
The State Government has pressed the airport to fast-track another runway since late 2012, when it promised a go-ahead by April last year.
Perth Airport has spent the past nine months refining a plan for the runway with air traffic controller Airservices Australia and airlines, with a final business plan expected to be agreed soon.
But it will be at least four years before the runway is operational because a two-year environment study is needed. And pressure continues to mount on the airport's infrastructure despite the mining slowdown.
For the six months to December 31 last year, passenger numbers through Perth increased 2 per cent to 7.12 million, with a record 400,290 using the international terminal in December.
There are now four peak periods at the airport midweek - early morning, late morning, early afternoon and late afternoon-evening - when it cannot handle any more landings and limited departures.
Changing take-off times to off-peak is not possible for airlines that support resources companies because of the need for their planes to get two rotations a day to mine sites.
Last year, it was estimated congestion at Perth Airport was costing airlines $24 million in wasted fuel and related costs.
Perth Airport has experienced extraordinary passenger growth - an average of 9 per cent a year since 1963.
This is about twice the world average.