Standard & Poor's on Friday revised its outlook to "negative" from "stable" for Philadelphia International Airport's revenue bonds, but the ratings agency reaffirmed it's A+ underlying rating on the airport's debt.

S&P said in a credit report last month that it could lower the rating if American Airlines Group Inc. "adjusts the size and breadth of its network" in Philadelphia. "Although we believe local air travel demand will remain near current levels," S&P said, "we believe PHL could experience a material drop in connecting traffic, which accounts for nearly 45 percent of total enplanements," which are arriving and departing passengers.

Philadelphia International passenger traffic was up 1 percent last year to 30.5 million air travelers.

"American Airlines Group has publicly stated on numerous occasions our ongoing commitment to the Philadelphia hub which includes the recent announcement of new nonstop service to one international and four domestic destinations not currently served from the airport," said airline spokesman Todd Lehmacher. "It is also with great pride that American Airlines Group continues to partner with the City of Philadelphia on controlling expenses making it the lowest cost hub airport in the Northeast."

- Linda Loyd