ATPL · Navigation · Oxford Atpl Book General Navigation 6th… lesson — Page 449, Lesson 428

Let’s look at this table together. This is a sunrise table, and it’s one of the most practical tools you’ll use in general navigation. I want you to understand exactly what it gives you, how to read it, and why it matters for flight planning. The table is titled “Sunrise,” and it’s laid out with latitude down the left-hand side, from N 72° down through N 60°, N 50°, N 40°, N 30°, N 20°, N 10°, then 0° at the equator, and down to S 10°. Across the top, the months run from June through July and August, and within each month the days are broken out — you’ll see columns for the 1st, 4th, 7th, 10th, 13th, 16th, 19th, 22nd, 25th, 28th, and 31st. So the table gives you the time of sunrise for a given latitude and a given date. Now, the times are in hours and minutes — the “h” and “m” at the top of the columns tell you that. And the times are in UTC, which is the standard reference for all navigation. So if you’re at N 50° on, say, the 1st of June, you read across that latitude row to the June 1st column, and you get 03 hours 53 minutes UTC. That’s when the sun rises at that latitude on that date. Let me walk you through a few of the values so you can see the pattern. At N 72°, the earliest sunrise in the table is 00 hours 49 minutes on June 1st, and it gets later as you move through the month — 01 hour 30 minutes on July 1st, 01 hour 58 minutes on August 1st, and so on. At N 60°, June 1st is 02 hours 39 minutes. At N 50°, June 1st is 03 hours 53 minutes. At N 20°, June 1st is 05 hours 23 minutes. At the equator, 0°, June 1st is 05 hours 59 minutes. And at S 10°, the value is 06 hours — that’s the last entry in the table. Now, here’s the key relationship I want you to see. As you move from high northern latitudes down toward the equator, the sunrise times get later — later in the morning, in UTC terms. That’s because at high northern latitudes in June, the days are very long and the sun rises very early. As you go south, the sunrise gets later. And the table also shows that within a given latitude, the sunrise time changes through the months — it gets later as you go from June into July and August, because the days are shortening after the summer solstice. There’s one more thing in this table that’s important, and it’s the letter “G.” You’ll see it in the high-latitude rows — at N 72°, N 70°, N 68°, and N 66°. The “G” stands for “G” — it indicates that the sun does not rise at all on that date at that latitude. This is the polar night condition. At very high latitudes, during part of the year, the sun stays below the horizon for the entire 24-hour period. So instead of giving you a time, the table marks those dates with a “G” to tell you there is no sunrise that day. So, to use this table properly: you identify your latitude, you identify your date, and you read the time of sunrise in UTC. If you see a “G,” you know the sun doesn’t rise at all that day. That’s the whole structure of the table, and it’s a tool you’ll use to plan flights where daylight matters — for example, when you need to know when it gets light for a visual approach, or when you’re planning a flight that might operate around dawn or dusk. Let me just make sure you’ve got the reading method down. Pick a latitude, say N 40°. On June 1st, the value is 04 hours 48 minutes. On July 1st, it’s 04 hours 49 minutes. On August 1st, it’s 04 hours 51 minutes. You can see the progression. And at N 30°, June 1st is 05 hours 01 minute, July 1st is 05 hours 02 minutes, August 1st is 05 hours 03 minutes. The pattern holds — later sunrise as you go south, and later as you move through the summer months. One more thing to note: the table only goes down to S 10°, and the values there are around 06 hours. So the table covers the northern hemisphere summer, which is when the sun rises early in the north and later near the equator, and it gives you the exact UTC time for each latitude and date. That’s the sunrise table. It’s a straightforward lookup tool, but the “G” entries and the UTC times are the two things you must always interpret correctly. Now, if you’re ready, we can move on to the next part of the time chapter.