Here's the setup — Page 453, Lesson 443

I want to walk you through what this page actually is, because at first glance it looks like a wall of numbers. This is a Sunset Table — a standard page you'll find in the Air Almanac or the Nautical Almanac, and it's used for a very specific navigation task: converting between Local Mean Time and UTC (Universal Time Coordinated) using the time of sunset. Here's the setup. The table is arranged by latitude, and you can see the latitude values running down the left-hand side: N72, N70, N68, N66, N64, N62, and N60. So this particular page covers latitudes from 60° North up to 72° North. The columns across the top are the dates — and you can see the months October and November, with the days numbered 2, 5, 8, 11, 14, 17, 20, 23, 26, 29, then 1, 4, 7, 10, 13, 16, 19, and so on. Now, the key thing to understand is the format of the times. Each entry is given in hours and minutes — you'll see the column headers marked h and m. So when you read a value like 17 16, that means 17 hours and 16 minutes. And here's the critical part: these times are in UTC. The whole point of this table is that it gives you the time of sunset at Greenwich for a given latitude and date. Let me show you how to read one specific entry so the structure makes sense. Look at the row for N60 and the column for October 2. The value there is 17 31 — that means sunset occurs at 17 hours 31 minutes UTC. Now look at the same row, N60, but move to November 19 — the value is 15 36, so sunset is at 15 hours 36 minutes UTC. You can see the pattern: as we move from October into November, the sunset times get earlier, because the days are getting shorter in the northern hemisphere. Now, here's the real navigation application, and this is what makes the table useful. The table gives you sunset time at Greenwich. But you're not at Greenwich — you're somewhere else, at some longitude. So here's the procedure: you take the tabulated sunset time for your latitude and date, and you apply your longitude correction to convert it to your own Local Mean Time. Let me walk through the logic. The Earth rotates 360° in 24 hours, which works out to 15° of longitude per hour, or 1° per 4 minutes. So if you're east of Greenwich, your local time is ahead of UTC — you add the longitude correction. If you're west of Greenwich, your local time is behind UTC — you subtract. So the table gives you the UTC of sunset, you convert that to Local Mean Time using your longitude, and that tells you when the sun actually sets at your position. And here's the practical reason a pilot cares about this. Sunset time is used to determine whether you need to fly under Instrument Flight Rules (IFR) or Visual Flight Rules (VFR). Regulations often key off the time of sunset — for example, night flying restrictions, or the requirement for certain equipment. So this table lets you compute, for your position and date, exactly when sunset occurs, and therefore whether you're operating in day or night conditions. One more thing to notice about the table's structure. You'll see the latitudes are spaced 2° apart — 60, 62, 64, 66, 68, 70, 72. And the dates are spaced 3 days apart. So if your exact latitude or date falls between the tabulated values, you interpolate — you estimate the intermediate value between the two nearest entries. That's standard practice with these almanac tables. Also, you'll notice the table has a "SUNSET" label at the top, and there's a "Lat" column header — that's just shorthand for latitude. And you'll see the degree symbol ° next to the latitude values, confirming these are degrees of latitude. So to summarize what this page gives you: for any latitude between 60°N and 72°N, and for any date in October or November, you can look up the UTC time of sunset. You then apply your longitude correction — 15° per hour, 1° per 4 minutes, adding if east, subtracting if west — to get your Local Mean Time of sunset. And that local sunset time is what you use for flight planning decisions about day versus night operations. That's the complete picture of this table. It's a tool you'll use in real navigation work, so it's worth being comfortable reading it.