Air transportation expenses in 2010 of $2,425 million decreased by $201 million, or 7.7%, from 2009. Domestic air expense of $1,976 million decreased $38 million, or 1.9%, compared to 2009. This was primarily due to lower mail volume and shifts from higher cost air transportation to lower cost highway transportation created by the NDC implementation.

For 2010, international air expense of $449 million decreased $163 million, or 26.6%, compared to last year as a result of lower volume, decreases in foreign postal transaction fees, and negotiated air carrier rates.

Air transportation expenses in 2009 decreased $421 million, or 13.8%, compared to 2008 expenses of $3,047 million. Domestic air expense decreased $322 million, or 13.8%, and international air expenses decreased $99 million, primarily due to lower volume and a decrease in foreign postal transaction fees compared to 2008.