The FAA has published Notice 8900.672, which provides authorized operators with updated and new boundary changes for certain polar areas of magnetic unreliability (AMU). These areas, where magnetic compasses are highly unreliable and unusable, apply to Part 91K and Part 135 operators that hold letters of authorization (LOA) B040 and/or B050.
Guidance for issuing B040 LOA now designates a Northern and Southern AMU. The Northern AMU is the area within 1,000 nm of the Northern magnetic pole, except for airspace over Alaska and its territorial waters. In addition, the FAA designates Canadian northern domestic airspace as part of the Northern AMU. The Southern AMU is the area within 1,000 nm of the southern magnetic pole. Previously, there was no AMU designated for B040 LOA.
The boundary of the B050 LOA South Polar area of operation now begins south of 60 degrees South latitude. Previously, the South Polar area of operation began south of 67 degrees South latitude. This change also affects three areas abutting the South Polar area, which all now end at 60 degrees South latitude—Central and South Pacific Ocean, South Atlantic Ocean, and Indian Ocean. This change also aligns the area with the OpSpec for extended operations, which has been defining the AMU as 60 degrees South.