The first incident happened on Wednesday night, when two F-16 fighter jets intercepted a private plane that violated flight restrictions just before 5 p.m. The single-engine Cessna 117 was forced to land at the Camarillo Airport.
Then on Thursday at about 6 a.m., a Mooney M2O entered airspace near Fullerton while the president was attending a breakfast fundraiser. The Mooney M20 was forced to land at the Chino Airport, and the pilot was questioned by authorities.
Just three hours later, a single-engine Cessna 206 was intercepted at 9 a.m., and then a Piper Cherokee PA 28 was also intercepted at about 9:30 a.m.
Airspace restrictions are put in place during presidential visits for security. But one local pilot, who was not involved in any of the incidents, said it's fairly easy to take off without realizing the flight restrictions in place.
"One of the things is, the president moves around a lot, so he'll be in three different places in a day," said local pilot Barry Halsted. "It's difficult to follow those things."
The Federal Aviation Administration is investigating all of the incidents. So far, there is no indication the president was in any danger.
During Mr. Obama's visit last month, a plane was intercepted and forced to land in El Monte. Then on Feb. 16, a small plane was diverted to Long Beach Airport. During a search of the aircraft, authorities discovered marijuana.