Let me orient you to the structure — Page 444, Lesson 410

This is a table of sunset times. Let me walk you through exactly what you're looking at, because this is a tool you'll use constantly in real flight planning. What we have here is a sunset table — a tabulated listing of the local mean time of sunset for a range of latitudes, across the months of February, March, and April. The whole page is built around one idea: given your latitude and the date, you can read off the time the sun will set. Let me orient you to the structure. The columns are the months — February, March, April — and within each month there are columns for the days: 16, 19, 22, 25, 28, then 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, then 2. So the table runs from mid-February through the end of April, in three-day steps. The rows are latitudes. Look at the left-hand column: you'll see N 72, N 70, N 68, N 66, N 64, N 62, N 60, then N 58, N 56, N 54, N 52, N 50, then N 20, N 10, then 0 — the equator — then S 10, S 20, S 30, S 35, S 40, S 52, S 60. The "N" means north latitude, "S" means south latitude, and the number is the latitude in degrees. Now, the times. Each entry is in hours and minutes — the format is hours, then minutes. So an entry like 15 39 means 15 hours 39 minutes, which is 3:39 in the afternoon. An entry like 18 08 means 18 hours 08 minutes, which is 6:08 in the evening. These are the local mean times of sunset. Let me read a few specific values so you can see the pattern. At N 72 — that's very far north, 72 degrees north — on February 16, sunset is at 15 39, that's 3:39 PM. By April 2, at that same latitude, sunset is at 19 17 — 7:17 PM. So you can see the days lengthening dramatically as spring progresses. At N 60, February 16 gives 16 52 — 4:52 PM — and by April 2 it's 18 45 — 6:45 PM. At N 50, February 16 is 17 19 — 5:19 PM — and April 2 is 18 33 — 6:33 PM. Now look at the equator, the row marked 0. The values are all around 18 09 to 18 14 — roughly 6:09 to 6:14 PM — and they barely change across the whole period. That's the key physical point: at the equator, day length is essentially constant all year, so sunset stays near 18:00 local time. Now go south of the equator. At S 30, February 16 gives 18 47 — 6:47 PM — and by April 2 it's 18 00 — exactly 6:00 PM. So in the southern hemisphere, the days are getting shorter as we move from February into April — the opposite of the northern hemisphere. That's the seasonal reversal you must always keep in mind. At S 60, February 16 is 19 50 — 7:50 PM — and April 2 is 17 36 — 5:36 PM. A big change, in the opposite direction. So the whole table is a compact way to answer the question: at my latitude, on this date, when does the sun set? You find your latitude row, you find the date column, and you read the intersection. One thing to notice: the table is in three-day steps — 16, 19, 22, 25, 28, then 3, 6, 9, and so on. So if your date falls between the listed days, you would interpolate between the two nearest columns. And the latitudes are also given at discrete values — 72, 70, 68, and so on — so if you're at a latitude between two listed rows, you interpolate between them as well. Also note the times are local mean time, not standard zone time and not daylight saving time. That's an important distinction for flight planning — you may need to convert this to the time zone you're actually operating in. This is the kind of table you'd use to determine, for example, whether you'll still have daylight for a visual approach, or to plan a night-flying operation, or to compute the duration of daylight for a leg. It's a standard navigation reference — you don't compute these times, you look them up. So the skill here is simple but precise: identify your latitude, identify your date, read the sunset time in hours and minutes, and remember which hemisphere you're in so you know whether the days are lengthening or shortening.