Federal authorities launched an investigation after a United Airlines passenger jet nearly collided with a military helicopter during its approach to John Wayne Airport in California.The aircraft carrying 168 people came within 500 feet of a California National Guard Black Hawk helicopter before pilots leveled the plane to avoid a mid-air impact.Air traffic control audio captured a controller admitting an error shortly after the United flight from San Francisco was forced to pause its descent to Santa Ana.This incident follows a recent
FAA mandate requiring radar separation for all aircraft after multiple fatal collisions highlighted the dangers of visual flight rules near airports.