The flight from Washington to Texas landed at Nashville airport, in the southeastern state of Tennessee, after passengers alerted the crew to the smell of burning sulphur.
Lynne Lowrance, a spokeswoman for Nashville International Airport Authority said all 99 passengers and their luggage were taken off the plane and searched.
An unlucky canine team was also brought in to sniff the aircraft for explosives.
After intense questioning by the FBI, a woman passenger admitted to lighting matches on board the aircraft to conceal her gas, Ms Lowrance said.
“For a long time she did not admit to striking matches and I think that was just out of embarrassment,” she said.
“She did finally admit to it saying she had a medical problem about excessive gas.”
The unidentified woman was not charged, but “American did ban her from flying on their airline for a very long time,” Ms Lowrance said.