The flight to Chicago was running late. Then the co-pilot got sick, forced out of the Boeing 767 cockpit by vicious stomach flulike symptoms.

The captain of American Airlines Flight 1612 checked to see if any off-duty pilots were traveling on the flight from San Francisco to O'Hare International Airport on Monday.

No luck. But a flight attendant who is also a commercial pilot earned her wings all over again, officials said Tuesday.

The unidentified San Francisco-based flight attendant dutifully abandoned her beverage cart and put on a radio headset, replacing the ill first officer in the right seat of the jumbo jet's flight deck to help the captain during the landing.

"The flight attendant became the first officer on landing," American spokeswoman Mary Frances Fagan said. "The cockpit crew did an outstanding job handling the situation."

One pilot is fully capable of flying a Boeing 767. In fact, the sophisticated plane, equipped with an array of computers, can fly and land by itself.

But there is plenty of work for two pilots to do, especially during a descent to the crowded airspace around Chicago and at touchdown.

During the approach to O'Hare, the flight attendant read checklist procedures to the captain as he configured the aircraft for landing, and she handled other tasks, in addition to providing a second set of eyes in the cockpit, Fagan said.

No announcement was made to the 225 passengers on board about the change of pilots, and the plane landed normally, Fagan said.

The Chicago-based first officer, who vomited repeatedly during the flight, rested in the passenger cabin until the plane was parked at the gate in Chicago.

He was treated by paramedics and taken to a nearby hospital, where he was later released. He was recuperating at home Tuesday, officials said.

"This was an example of how our flight attendants are able to step up to the plate in an emergency," said Jeff Pharr, a spokesman for the Association of Professional Flight Attendants. "We are proud of what they do to keep passengers safe."

jhilkevitch@tribune.com