FAA Expands Use of 3-nm Separation at Mid-Altitudes

High-altitude en route aircraft separation in the U.S. will be 3 nm instead of the current five, effective July 13. The FAA’s just published Notice JO 7110.689 offers guidance on the expansion of 3-nm separation in airspace below FL180 up to and including FL230.

The agency said safety and analysis studies using analytical approximations, simulations and flight tests comparing flight characteristics of targets between 13,000 feet and FL180 to targets between FL180 and FL230 determined the increased probability of a loss of separation at the higher altitudes is negligible compared to similar events in airspace below FL180.