The teenager was treated by park staff before being taken to a local hospital by ambulance and then airlifted to Albany Medical Centre, 55 miles away.
Park spokeswoman Jessica Hansen says there appeared to be no malfunction on the ride, but that Six Flags has closed the attraction for further review.
The ski lift-style gondolas, one of the oldest rides in a park that opened in 1954 as Story Town, offer riders a slow-moving view of other attractions.
"Because if she was going to fall you know I wanted to be there to at least do whatever I could to try to save this girl", Winchell said.
Witnesses said she was lifted up and carried to a golf cart where emergency workers arrived to help her. The ride continued to dangle her for 2-3 minutes before it stopped. Her brother was uninjured.
"I said: "It's OK!"
Howard, a contractor from Schenectady, was treated and released for a minor back injury after the rescue.
Crowds which had gathered to watch the drama unfold cheered as the men took the girl to safety. They did not know how she had fallen out of the ride.
Sunday was just another day here at Great Escape, but the Sky Ride was closed.
The New York Daily News said she was taken to a nearby hospital and she is expected to survive without any serious injuries. Luckily, fearless park staff and guests banded together and coaxed the girl into making a 20-foot (6 meter) leap of faith.
When asked about safety procedures at the park, Hansen said all rides have a standard evacuation plan.
"The safety and security of our guests is our top priority", park spokeswoman Jessica Hansen told the Post-Star in an email.