The FAA has launched an investigation after a drone had an apparent close call with a jet near McCarran International Airport. Video circulating online shows the drone hovering as what appears to be a Frontier Airlines jet flies almost directly beneath it. FAA regulations generally prohibit drone operators from flying above an altitude of 400 feet, near other aircraft or in controlled airspace like the area near an airport. There are, however, instances in which pilots can apply to have those rules waived under specific circumstances. It's not clear under which regulations this pilot was flying.