Another Near Miss Took Place in the Sky Tuesday

There was a second unnerving near miss in US skies this week, this one over Southern California, ABC News reports. A United Airlines Boeing 737 with 168 people on board was on final approach to John Wayne Airport in Santa Ana on Tuesday night when an Army National Guard Black Hawk helicopter crossed in front of it, according to the Federal Aviation Administration. The FAA is investigating the incident, CNN reports.

Air traffic control had already warned the United pilots about the helicopter, and their cockpit systems issued the highest-level collision alert, the airline said. The crew leveled the jet as directed and landed without incident. Preliminary radar data indicates the aircraft were separated by about 525 feet vertically and less than a third of a mile horizontally. The Guard says the Black Hawk was returning from a training mission along an established visual route and was in contact with controllers; it also landed safely. The FAA is investigating whether a newly adopted rule—meant to end reliance on "see and avoid" visual separation between planes and helicopters and require radar-managed spacing—was properly applied. (The new rule comes in the wake of last year's collision between a Black Hawk and an American Airlines plane that killed 67, USA Today reports. The NTSB says it is aware of the incident.