There were four airspace violations by private planes during Sunday's Super Bowl at Levi's Stadium in Santa Clara, California, the Federal Aviation Administration said.
FAA spokesman Ian Gregor told NBC Bay Area on Monday that the he knew of four "temporary flight restrictions" during the game, one more than was originally reported on Sunday.
In general, FAA spokeswoman Laura Brown said, pilots could face sanctions ranging from warning letters to license suspensions or revocations.
The FAA declared the air space above the stadium a "no fly zone" during the Super Bowl game between the Denver Broncos and the Carolina Panthers. That meant drones and other aircraft were not allowed to fly within 32 miles of the stadium between 2 p.m. and midnight on game day.
Major Katrina Andrews, a spokeswoman for the air component of the North American Aerospace Defense Command, said the violators were not drones. Instead, she said they were pilots of private planes, such as small Cessnas, who didn't read their notices telling aircraft to stay away from the stadium during the big game. The FAA said these four planes violated the airspace: a Cessna 150, a Cessna 172, a Vans RV 6 and a Beechcraft BE35.
She said the pilots received an alert that they were violating the air space and were escorted or diverted to the Livermore Municipal Airport or Palo Robles, where they were headed anyway.
"It appears they had not read their notice to airmen (NOTAMS), which explains the parameters of the restricted area," she said.
NORAD is the agency charged with the missions of aerospace warning and aerospace control for North America.