NORTH Air operators provided varied levels of support, but less than 15% actually opposed change aircraft when they use the Magnetic heading reference for navigation. Cheng points out that the main sources of potential mismatch are the magnetic variation (MagVar) tables that are part of the inertial reference system and the flight management computer system. There is a need for the operator to update the MagVar tables regularly in both these complex interacting systems; if they are updated late or not at all or if one table is updated and the other is not the outputs can differ, confusing the autoflight systems. Other pilot tools, such as synthetic vision systems, can also be affected by mismatches. The potential for error No-one is suggesting that operators give up their standby magnetic compasses, but organisations such as the General Aviation Manufacturers Association and the Aircraft Owners and Pilots Association warn against forcing GA pilots while flying to read their standby compass, apply the local magnetic variation, and set their gyro-driven directional indicators to True. The potential for error, they argue, is high. Both are also nervous about GA aircraft fitted with horizontal situation indicators (HSI) slaved to flux valves that provide Magnetic headings. Their concern is the expense of fitting converters to make the HSI read True. Meanwhile, there are those who accuse detractors of exaggerating the problems, and of ignoring the capabilities of Global Navigation Satellite Systems, widely used by all sectors of GA. Your views on the change ICAO conducted a survey to measure support for a Mag2True change. It received a robust response from more than half of the contracting states and found that less than 10% were resolutely opposed to it. Those most in favour included ANSPs and flight procedure designers. Air operators provided varied levels of support, but less than 15% actually opposed change. ICAO also noted that many air operators already use True North procedures in remote and oceanic airspace, and in polar regions. Four objectives in advance of transition have been mooted: development of a global ConOps; development of strategies for implementing True North; analysing the potential safety risks and mitigations; and identifying the ICAO Air Navigation Commission Panels that will be impacted and proposing tasks accordingly. Nav Canadas ConOps argues that the move to True is essential for aviations future: The only problems would be those of practically implementing it. While it would be a large-scale undertaking, it would also be a one-off operation that, once completed, would be final. The AHRTAG chairman, Nav Canadas Anthony MacKay, sums up the groups conclusion: The risks of change are known and manageable. The transition will require careful planning and implementation, most likely through ICAO. To remain on Magnetic continues to allow a latent threat to safety to reside within our aviation safety system. Finally, ICAOs survey found that there is a very high understanding of the many benefits of a True North reference, including more accurate navigation performance and eliminating errors caused by MagVar. 14 THE LOG Spr 24 pp12-14 True North.indd 14 16/02/2024 11:30