"The Air Force has not been tasked with that mission," Schwennesen said.
Rescuers had been preparing the patients to be loaded into metal baskets and then lifted off the Venezuelan boat, Air Force officials said. Each basket was to be hooked via a steel cable to a separate helicopter overhead.
One rescuer would then latch on to the outside of the basket as it is hoisted up to the helicopter so the patient can continue to be monitored.
"It's very difficult to hoist off a ship, because the ship is moving, the waves are moving up and down, the wind is blowing things around," said Tech. Sgt. Brandon Daugherty, an Air Force rescuer who has done such missions but was not part of the latest. "It takes a lot of coordination."
It was the second such dramatic sea rescue by U.S. crews in recent weeks.
Last month, three federal agencies, a fixed-wing aircraft, a Navy warship and scores of personnel successfully rescued an ill American baby girl and her family from their broken down sailboat 900 miles off Cabo San Lucas.