The crew lowered a rescue swimmer on a hoist who pulled out the body of a woman who had been trapped inside.
Video showed Petty Officer 2nd Class Derrian Duryea buffeted by winds and spraying water as he was lowered 24 metres to the car through falling snow.
After slowly spinning and swinging past the car, he was able to grab hold on the passenger side and open the door.
“As I was coming down, I was just really focused on how am I going to get in this car when there’s, you know, pretty much rapids coming over the car right next to Niagara Falls,” Petty Officer Duryea said after returning to Selfridge Air National Guard Base, north-east of Detroit, where the crew is stationed.
“My sole focus was which window or door am I going in.”
“Luckily, the car was unlocked and I didn’t have to break out any windows and I was able to open up the passenger side door and push it up against the current,” he said.
Throughout the operation, the helicopter’s pilot, Lt Chris Monacelli, and flight mechanic Jon Finnerty kept an eye on the waterfall’s icy mist as it coated the hovering aircraft, including the windows, further limiting what they could see.
“A lot of bigger planes have de-icing capabilities, but we don’t,” Lt Monacelli said. “We have a lot of discussions and training for what we’d do if we got into that situation, because if you do accumulate enough ice on the helicopter, it will fall out of the sky.”
About two minutes after entering the car, with water surging around the vehicle and over the brink of the falls about 45 metres downstream, Mr Duryea emerged and signalled for the crew to hoist him and the motionless driver, a woman in her 60s, from the water.
It was unclear how the car got into the Niagara River. Witnesses reported seeing it floating near a pedestrian bridge, where it was believed to have gone in. Roads in the area were slippery.
Conditions in the air were no easier, with snow limiting visibility to 800 metres for the coastguard crew that had assembled for a training flight at Lake St Clair, Michigan, when they were dispatched to Niagara Falls, New York.
“At one point we were literally just flying down a street because we saw the road and we were trying to avoid the windmill farm that’s just west of Niagara,” Lt Monacelli said. “So, we’re flying the road as these gigantic windmills are popping up like a half mile away from us.”
After the rescue, the car remained almost completely submerged, with only part of the roof and open boot visible, in the rapids upstream from the American Falls, one of three waterfalls that make up Niagara Falls. Onlookers watched as emergency crews prepared to try to pull the vehicle from the water.
Authorities said the driver lived in the area. Her name was not released pending notification of her relatives.
New York Park Police Capt Christopher Rola said his department’s swift-water rescue teams were unable to get to the car because of its location. Police had used a drone to determine it was occupied.
“It was an incredible job by the Coast Guard,” Capt Rola said. He said rescuers have never been called to a vehicle so close to the edge.
Capt Rola said investigators would try to determine whether the vehicle wound up in the water by accident or intentionally.