The airport expected full operations to be resumed by the end of Monday.
US Airways said it canceled 31 flights early Monday. The cause: "Residual problems from Sunday," spokesman Todd Lehmacher said.
Airport spokeswoman Victoria Lupica said that once power to A-East was restored, "we had to reopen security checkpoints, reopen the exit lanes, get the concessions up and running, just bring everything back up. Most importantly, we are getting passengers to the gates and to the planes."
American Airlines, which operates in A-East, worked with passengers to reschedule, and added flights to Chicago and Miami.
The National Weather Service said eight inches of rain fell in the city Sunday.
"The good news is, operations are resuming," US Airways' Lehmacher said Monday morning.
At 6 p.m. Sunday, power was out briefly in several terminals, which affected computers in the B and C Concourses, where US Airways operates.
US Airways diverted three trans-Atlantic flights from Europe on Sunday to Atlantic City International Airport, where the planes refueled and eventually continued to Philadelphia.
Outbound US Airways trans-Atlantic flights left late Sunday, which caused a ripple effect Monday with flights returning late from Europe. Trans-Atlantic flights were expected to leave late again Monday from Philadelphia. "Everything is operating; it's just going to be late," Lehmacher said.
"When they depart late, they are on the ground only for two or three hours in Europe, then they come back late," he said. "It takes a couple days sometimes to catch up."
Power was not restored at US Airways' hub control center at the Philadelphia airport until midmorning Monday. The control center manages ground movements for all airlines at the airport. "That complicated things," Lehmacher said.
The weather affected flights airport-wide. "If you had a canceled flight Sunday night or a missed connection because of a late flight, those had to be re-accommodated - and that was airport-wide," Lupica said.
"The A-East Terminal building is back up and running. Certainly at ticketing, everything has resumed normally, because computers are back up," she said. "Sometimes it takes a while for everyone to get back right-sided."
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