Pittsburgh Airport was once a thriving hub in the US Airways network, upgraded in the early 2000s to handle 35 million passengers per year. But walk the concourses today and in some areas you'll be lucky to see many active gates and passengers.

At the time, USAir (later US Airways) and its Express partners flew to more than 100 destinations from Pittsburgh. The airport's five airside concourses were constantly busy. However, as the rise of other carriers — particularly low-cost airlines like AirTran and Southwest — gained momentum at the airport, combined with the effects of the Sept. 11 terrorist attacks, the profitability of US Airways' operation declined substantially.

US Airways has now merged with American Airlines and, despite still being the largest carrier at Pittsburgh, its operation is but a shadow of its heyday. Today, the airline serves fewer than 15 destinations between its mainline and American Eagle fleets.

Pittsburgh has seen a decline in passenger figures to around the 8 million mark in the past 10 years, and some of its concourses are now quiet spaces for extended periods. These empty areas are proving expensive to heat, cool and keep in operation for the few flights operating.

Now, it has been put forward that demolishing some of the unused space could be a viable option for dealing with the problem.

At present, around 25 of the airport's 75 gates go unused and likely never will again, with parts of Concourse B mothballed behind a dividing wall. Consolidating into a smaller space that still has room to breathe — should work to add more daily flights pay off — is one way of saving money that is being seriously considered.

Facing up to the reality that the good old days of the Pittsburgh hub are gone for good, the CEO of Allegheny County Airport Authority, Christina Cassotis, is instead focusing on turning it into a great origin and destination (O&D) airport with more, and better, routes. She has already added more than 100 weekly flights during her tenure, but there are still gaps in access the West Coast and Europe, which are seen as key targets.

Speaking to Action News 4 in Pittsburgh, Cassotis said of the unused space: "We're paying to heat it. We're paying to cool it. We're paying to run moving walkways where there are not passengers. The systems are old." She added, "We have a responsibility to look at keeping our costs low for our airline tenants, and creating an airport that reflects the vibrancy of this region. When you have too much space, that's not what happens."

Demolishing the space is not the only option being considered. The open areas could be used as areas for community engagement, albeit in a difficult-to-access airside area that still costs the airport to keep open.

A master plan laying out development at Pittsburgh Airport is expected to be published in the near future.