An alarm in the cockpit (called the Collision Alert Avoidance System) prompted the pilot of Air Force One to quickly turn left and ascend 300 feet, reports CBS News Correspondent Sandra Mitchell.
The two planes never violated the 1,000-foot vertical separation requirement, White House spokesman Joe Lockhart said.
"This was not a near-miss by any calculation," he said. "They at all time maintained required separation."
A spokesman for the Federal Aviation Administration says the president was never in any danger. The pilot took the president's plane higher simply as a precaution.