On Sunday night, he came home with a pair of skinned knees and assorted bruises.
Keepers, 40, logs a lot of hours in the air as a caddie for the LPGA Tour. On Sunday, he was headed home to Augusta via a red-eye flight from San Francisco to Washington, D.C.
About 3 a.m., he was awakened by a ruckus coming from the back of the plane. About that time, the pilot announced an emergency landing over the intercom.
Keepers looked back toward the rear of the plane in time to see a flight attendant take a tumble down the aisle. Two male passengers were moving in on the culprit: an angry woman standing in the aisle screaming.
Acting on "instinct," Keepers said he immediately rushed to the back of the plane to help. The fracas was in a wide spot in the aisle near two emergency exits. Keepers feared she would open one of those doors.
"I didn't want anything to happen," he said Tuesday by phone.
With the help of the other passengers, the woman was pinned to the floor of the plane. But she still had plenty of fight in her. Keepers said he grabbed an arm and her head and held on. Several times the woman tried to bite him.
Eventually they were able to lift the woman off the aisle, handcuff her and lead her to the rear of the jet, where they cinched her tight into a seat. Within minutes, the plane landed in Omaha, Neb., and local authorities boarded.
Marie Rita Manzoni was charged Tuesday with interfering with a flight crew, a federal charge, The Associated Press reported.
According to court papers, United Airlines Flight 142 was diverted to Omaha about 5 a.m. Monday after Manzoni, who screamed about terrorists on board, was subdued by passengers.
The Boeing 757 was carrying 148 passengers and six crew members. Manzoni was returning to her home in Maryland, the AP said.
Keepers wasn't exactly sure what set off the woman. He said another passenger told him that she made some sort of threat about blowing up the plane. When he tackled her to the floor, he said, she was shouting: "I love my country. I don't want to hurt anyone."
Another passenger, Lauren Airey, told Omaha television station WOWT that a flight attendant was trying to subdue the passenger after an argument turned into a fight.
She said other passengers took charge and "dog-piled" the woman.
A spokeswoman for United Airlines said in an e-mail that the flight was "diverted to Omaha for assistance from the authorities," who took over when the plane landed. She gave no other details.
Keepers, a caddie for 15 years, told himself after Sept. 11 that he would take action if his plane was ever hijacked.
He said he felt no hesitation when he saw the situation unfolding.
"It was a shot of adrenaline," Keepers said. "Now I know how cops feel."