Planners at Seattle-Tacoma International Airport said a strategic priority for the growth of air cargo there is to improve the airport's penetration of the international air freight market.

Anticipated growth at SeaTac to 968,000 tons by 2020 from last year's 451,000 tons will be driven in large part by trans-Pacific air freight, which is projected to increase nearly 9 percent a year through 2001, according to a memo prepared by Alan Arch, director of aviation marketing, and Michael Feldman of Sea-Tac's aviation-support line of business.That forecast drives other master-planning projections, including the doubling of warehouse space and truck docks as part of a redevelopment of Sea- Tac's northeast cargo area and the development of a south aviation area or a nearby off-site location.

There is room to improve SeaTac's international air freight profile, the memo continued, because 44 percent of Washington state's air cargo exports move through other West Coast airports.

"There is sufficient surplus demand to sustain additional growth and new capacity," it said.

Vancouver International Airport is SeaTac's main international competitor. The British Columbia airport is "aggressively marketing itself as the premier West Coast gateway for both passengers and cargo," the SeaTac memo said.

Vancouver airport last year lowered its landing fee for cargo aircraft 25 percent and waived a provincial fuel tax.

For domestic cargo operations, SeaTac's big competitor is nearby Boeing Field, a smaller general-aviation airport and a Boeing Co. test-flight center that has been able to take advantage of SeaTac's congestion and lure Airborne Express and Burlington Air Express to its fold. United Parcel Service's Seattle air operations have been located at Boeing Field since 1982.

Given its size, it's not clear how much Boeing Field can expand or how many other SeaTac customers it could accommodate.

Air cargo in general at SeaTac is a net plus in financial and economic terms, the memo said, so it is vital to retain existing cargo flights.

Cargo-only flights represent 5.6 percent of the total at SeaTac, but nearly 8 percent of total landed weight. Cargo flights create more than twice as many jobs as passenger flights, and air-cargo volume is expected to grow at a faster rate than passengers over the next 20 years.

SeaTac officials said the Port of Seattle, which owns and operates the airport, should pursue creative financing alternatives for developing cargo facilities, such as joint ventures with the private sector.

In addition, they said, the potential of special-purpose facilities, such as a distribution center or a foreign trade zone extension, should be evaluated as ways to enhance international cargo growth.

Federal Express and the port have been in negotiations to expand the express carrier's SeaTac facilities, including a 40 percent increase in its cargo facility; improvements to its sorting system; and a new ramp to park two additional aircraft.