DALLAS -- Standard & Poor's Corp. yesterday said that despite its June 1 downgrade of major airlines, the municipal ratings of U.S. airports are not threatened -- for now.

In a statement, however, the agency warned that uncertain financial performance by leading carriers could affect traffic and revenues at airports of all sizes throughout the nation.

On Monday, Standard & Poor's downgraded the debt ratings of AMR Corp., Delta Airlines Inc., NWA Inc., USAir Group Inc., and their subsidiaries, citing the continued contraction in the industry and financial concerns prompted by recent cuts in discount fares.

Todd Whitestone, managing director for transportation at Standard & Poor's, said yesterday that the agency had not yet waved a red flag over any specific airport or bond issue.

"We're going to go through them all," he said.

Analysts at other Wall Street rating agencies have said they, too, continue to monitor the financial health of airlines and how that affects airport credits.

In its statement, the agency reaffirm that the viability of specific airlines was an increasingly important credit concern to airports.

"Since one airline can be the dominant player at an airport, its activity could influence revenue variability at that facility," Standard & Poor's said. "Additionally, with the decrease in the number of major airlines, there is less likelihood of an airline starting service at a hub previously served by another airline."

The agency said the latest fare ware has triggered cost cutting by carriers that could affect their connceting traffic. Still, the report says the kwy to understanding the impact of the contraction among airlines is air traffic demand.

Airports with a large amount of local traffic are not at risk as much as those with primarily connecting traffic.

Mr. Whitestone said the rating agency is increasinly concerned about the fiscal health of carriers, noting that their corporate ratings have been on a five-year decline.

"More of these carriers are getting closer to the border line between investment grade and noninvestment grade," he said. "A lot of these credits are deteriorating closer and closer to the triggers that we watch for."

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