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FAA Expands Use of 3-Nautical-Mile En Route Separation to Flight Level 230

June 11, 2015

The FAA is expanding the use of 3-nautical-mile en route separation under certain conditions.

The agency’s recently issued Air Traffic Organization Policy Notice states that when certain conditions are met, the FAA will expand use of 3-nautical-mile en route separation from below FL 180 up to and including FL 230.

The new policy takes effect on July 13.

Where it can be employed, the FAA said it would increase capacity 40 percent over the existing 5-nautical-mile en route separation standard. It is important to note that this new 3-nautical-mile separation standard will not apply in all airspace between FL 180 and up to FL 230, nor will pilots likely realize that reduced separation is or is not being applied. Also, no new pilot actions or requirements are required.

Before the FAA expanded the reduced separation standards, it conducted simulations, flight tests and made analytical approximations that compared the "flight characteristics of targets between 13,000 feet and FL 180 to targets between FL 180 and FL 230."

According to FAA officials, the safety analysis of the resulting data "determined that the increased probability of the loss of separation between Fl 180 and FL 230 was negligible, as compared to similar events in the airspace below FL 180."

"We're glad to see the FAA taking this step," said Bob Lamond, NBAA's director, air traffic services and infrastructure. "NBAA strongly supports reduced separation standards in the National Airspace System when they can be safely implemented."

View the FAA's Air Traffic Organization Policy Notice. (PDF)