Fighter jets were scrambled on Thursday to intercept two small planes that strayed into airspace over the Los Angeles area restricted for President Barack Obama.
The F-16 fighters responded after two single-engine planes, identified as a Cessna 206 and Cherokee PA 28, entered into the restricted airspace at mid-morning in separate incidents, NORAD said.
The fighter jets escorted both planes until they left the area and were directed to contact the Federal Aviation Administration, NORAD said.
In a similar incident on Wednesday, an F-16 intercepted a single-engine Cessna after it flew into the restricted airspace over Southern California. The fighter followed the plane until it landed at an airport less than 10 minutes later and was met by local law enforcement officers.
Each of the three cases involved private pilots unknowingly flying into temporarily restricted airspace and were not apparent threats, an FAA official who asked not to be named told reporters.
"In most cases it's a matter of the pilots not being aware of the notice to airmen that get issued by the FAA," NORAD spokesman Lieutenant Al Blondin said. "If they follow the proper procedures they should be aware there's a restricted area."
On May 11, fighter jets intercepted a small private plane over Southern California after it inadvertently entered airspace restricted for a visit by Obama.
Obama has been in the Los Angeles area as part of a West Coast fundraising tour ahead of the November presidential election. He was scheduled to leave Los Angeles on Thursday en route to a fundraising event in Las Vegas.