The recommended technique is a combination of two methods we've already… — Page 208, Lesson 187

I want to walk you through a powerful technique for correcting your track when you get a pinpoint fix during a flight. This builds on the 1-in-60 rule and the closing angle method we've been working with. The recommended technique is a combination of two methods we've already looked at. You mark up your chart with closing angle guidelines — those are the 5° and 10° lines radiating from your destination — and you also mark distance-to-go markers along your track. Then, when you get a fix, you apply a simple rule based on how far along the leg you are. Here's the pattern. If you get a fix a quarter of the way along your track, you alter heading by 4 times the closing angle. If you get a fix a third of the way along track, you alter heading by 3 times the closing angle. If you get a fix half-way along track, you alter heading by 2 times the closing angle. And so on. The fraction of the distance you've flown tells you the multiplier to apply to the closing angle. Let me walk through the example in Figure 11.16 to make this concrete. Imagine you're flying from point A to point B. You get a pinpoint at point C, which is about a quarter of the way along the leg. You measure the closing angle — that's the angle between your actual track from A to C and your desired track from A to B — and let's say it's 8°. Because you're a quarter of the way, you multiply that closing angle by 4. So your heading alteration is 4 × 8° = 32° toward track. That gets you onto a new track from C to B. Now, later you get another pinpoint at point D. This time, you're working with your new desired track from C to B. The closing angle DBC — that's the angle between your actual track from C to D and your new desired track C-B — is 2°. And your new pinpoint D is about halfway between C and B. So your new alteration, to starboard, is: 2 divided by 1, times 2°, which gives you 4°. The "2/1" comes from the rule: halfway means divide by 1, so it's just 2 times the closing angle. There's one critical point to bear in mind here. The closing angle must be calculated from the new track, not the original one. That new track from C to B won't be drawn on your chart — you have to visualise it. If you're using your 10° guidelines, remember they were drawn with respect to the original track from A to B. So you must mentally allow for the first closing angle when you measure the new one. Similarly, you must estimate the proportion you have travelled of the new distance CB, not the old distance AB. Now, the excerpt finishes with some practice questions. These are the book's practice questions — let's try them one at a time.