The FAA says recent evaluations of error reports occurring over oceanic airspace show that deviations, especially vertical large height deviations (LHD), have increased in numbers to the point where they exceed the agency’s safety target levels. That means increased risk for both private and commercial operators. An LHD occurs when an aircraft strays more than 300 feet from its assigned altitude.
Strategic Lateral Offset Procedure
Both Gander and Shanwick oceanic control areas (OCAs) are conducting a trial of reduced longitudinal separation standards–five minutes between eligible aircraft–in North Atlantic airspace. The separation minimum for turbojets maintaining constant Mach on the same longitudinal track in the North Atlantic minimum navigation performance specifications (MNPS) airspace is 10 minutes.