Spokane International Airport experienced a record year in 2017 and is expecting an additional 550 flights this month over the same period last year. On the back of this, it is pushing ahead with plans for expansion to meet future growth.

More than 3 million passengers used the airport last year, which is the highest number ever. It has highlighted how the current facilities lack the capacity to handle the number of flights and passengers at present, let alone what the airport might need to handle in the future.

The current three-concourse terminal buildings at Spokane are now largely outdated — particularly what is known as Terminals A and B, whose structures date from 1965. However, an ambitious renovation plan that was proposed in 2013 is now pushing ahead following five successive years of growth.

This $130 million restructuring project is known as Terminal Renovation and Expansion (or TREX). It will see a new security checkpoint for Terminals A and B, along with a new central baggage claim located between all terminals. A new canopy over the drop-off and pick-up zones will be built outside the terminal to protect passengers from the weather.

The most significant part of the works is the remodeling of the 2000-era Terminal C. It will include a new check-in hall, a two-story connector to Terminals A-B, a greeter area, new security screening checkpoint and an enlarged gate area. Discussions with tenants Alaska Airlines and American Airlines will take place next in order to minimize the impact on their services and make the most of the expansion.

"The expansion of terminal C allows us to balance the passenger load, which is important for the long haul to spread that out," said Matt Breen, director of planning and engineering for SIA.

Initially, a contract has been approved for the design work, giving the Architectural Alliance International group $2.8 million to come up with the fine details of the renovation.

Spokane's growth comes after the addition of five new routes last year and will see Frontier Airlines restarting service to Denver and Southwest Airlines to San Jose this month. Other major carriers here include Alaska Airlines and their partner Horizon Air, plus American Airlines, Delta and United.

"We have to grow to keep up with the times, especially with success of the new flights," said Spokane City Council President Ben Stuckart. "Facilities are the most important thing you have when you are a public agency like the airport."

Funding for the renovation work will come in part from a new $4.50 fee levied on all departing passengers. It will allow construction work to begin in 2019 once final approval and designs are received.

Following this initial stage of TREX, it is anticipated that Terminals A and B would be renovated to cope with current operations, but ultimately demolished to give space to a completely new terminal in their place. It is thought this would happen in the 2030s.