Now, why is this a problem — Page 112, Lesson 183

I want to walk you through a new topic now — polar navigation. This is a specialised area of flying that comes into play when aircraft operate at very high latitudes, and it introduces some unique challenges that you won't see on conventional airways. Let's start with the definition. Polar tracks are defined as North/South routes that involve navigation at high latitudes — specifically, above 65° North. So once you're operating north of that 65°N line, you're in the polar navigation environment. Now, why is this a problem? The excerpt gives us three specific reasons that make conventional airways navigation difficult, if not impossible. First, there is a lack of ground radio aids. Second, you have high rates of change of magnetic variation. And third, you have steep magnetic dip angles. These three factors together mean that the standard navigation methods you'd use at lower latitudes simply don't work reliably up here. Because of those reasons, magnetic compasses become unreliable, and reference to magnetic north becomes impractical. You cannot rely on magnetic heading as your primary reference. So how do we navigate instead? The excerpt gives us two main methods: navigation by reference to a grid navigation process, or reliance on inertial systems and satellite-based global positioning — that's GPS. Now, there's a specific point about VOR beacons in these areas. In regions where the rate of change of magnetic variation becomes excessive — particularly in close proximity to the North Magnetic Pole — VOR beacons are orientated to true north, not magnetic north. This is done to assist grid navigation. The excerpt specifically mentions that VORs in the Canadian Northern Control Area are oriented to true north. So if you're flying up there, your VOR references are based on true north, not magnetic. What about when your primary heading information comes from an Inertial Navigation System, or INS? The excerpt gives a clear caution: care must be taken to monitor the system for degradation or failure. And how do you monitor it? By reference to any other aid or method available. You cross-check the INS against whatever else you have — GPS, VOR, or any other source — to catch a problem before it becomes critical. There's also an important reminder about the autopilot. The excerpt states that there are a number of different ways in which the autopilot can become unobtrusively disconnected from the steering mode. That word "unobtrusively" is key — it means it can disconnect without giving you a clear warning or without you noticing. Therefore, regular checks of correct engagement are to be made. You must actively verify that the autopilot is still coupled and doing what you think it's doing. Finally, there's a recommended practice for when the navigation system is coupled to the autopilot. Where possible, the navigation system should display position coordinates throughout the flight. Those coordinates are then plotted 10 minutes after each waypoint. So you're not just relying on the system's display in real time — you're physically recording the position data at regular intervals to create a paper trail that confirms your actual track. The excerpt cuts off mid-sentence at the end, but that's the core of what we have on polar navigation for now.