Standard&Poor's Ratings Services has affirmed its 'A-' rating on the Public Building Authority of Sevier County, Tenn,'s series II-D-1 local government public improvement bonds, issued on behalf of the Metropolitan Knoxville Airport Authority (MKAA). The outlook is stable. We base the rating on our view of the following credit strengths: An historically strong liquidity position; Good airline diversity, with no carrier holding more than 30% of the market; and Its location, at the center of a stable and stable regional economic base. In our opinion, offsetting credit concerns include: Variable enplanement trends; High debt per enplanement; and A significant exposure to unhedged variable-rate debt, at approximately 41% of total debt, although large cash balances mitigate this risk somewhat.