After "eruptive activity" last year at the Cleveland volcano, University of Alaska Fairbanks scientist Steve McNutt noted that 90% of air freight from Asia to Europe and North America flies over Alaska airspace, and hundreds of flights fly through Anchorage's air space daily.

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After all, not only is the airline America's biggest freight-carrier to Asia, but it is the only convenient air access for big swathes of the mid-west.

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Freight contracted in 2011, but is reviving in many markets (though not Asia).

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UPS' international air freight business continued to face pressure from customers opting for slower but cheaper delivery options, particularly in Asia.

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