The airport gave an update through its Twitter account at 7:53 a.m. Wednesday, saying an earlier ground stop had been canceled and that American's computers were back up and running.
Delays for American Airlines passengers were expected to continue as the airline's systems returned to normal.
Word of the problem affecting the airline at PHL first came before 6 a.m. Wednesday.
Action News found long lines of passengers at American's ticket windows in Terminal C as employees were being forced to manually issue tickets and luggage tags.
Shortly after 6 a.m. the Federal Aviation Administration (FAA) issued a ground stop for all American Airlines flights departing to Philadelphia.
No other inbound flights or airlines were affected.
American Airlines spokesperson Victoria Lupica told Action News the problem happened after a scheduled power outage overnight.
When the power came back on, the airline's computer system did not reboot normally, Lupica said.
The outage affected only American Airlines passengers.
Delays were expected to continue as American's systems returned to normal.
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