So let's get into it — Page 408, Lesson 359

We're starting a new part of the chapter now — the practical business of how countries actually apply time corrections. So let's get into it. First, a key point: not every country uses a whole number of hours as its time correction. That choice is entirely at the country's discretion. So you'll find some unusual corrections out there. Two examples stand out: Chatham Island, which sits at 12 hours 45 minutes, and the Tonga Islands at 13 hours. Now here's the interesting bit — those latter countries, the Tonga Islands, are actually in the Western hemisphere. The correction is made because those countries want to keep the same day as their neighbours in the Eastern hemisphere. We'll come back to that idea later in this section. Now, the book gives you three lists of countries. Let me walk you through what each list means. List 2 covers countries close to the Greenwich Meridian that normally keep UTC as their Standard Time. And note — this list includes Great Britain. So for these places, UTC is their standard time; there's no correction to apply. List 3 covers countries generally to the west of Greenwich whose Standard Time is 'slow' on UTC — meaning their local time is less than UTC. The corrections given should be subtracted from UTC to give Standard Time, or added to Standard Time to give UTC. So if you're converting from UTC to local, you subtract; if you're converting from local back to UTC, you add. Same correction, opposite direction. Now, some countries are divided internally. Canada, for example, is divided by province — and even within some of those provinces, like the Northwest Territories, the correction is further subdivided by longitude. The USA is divided by states, with Alaska being sub-divided by longitude as well. Here's a practical tip for the exam: ATPL questions involving these areas will provide all the necessary detail. And you do not need to use terms like 'Eastern Standard Time' — those aren't given in the Air Almanac, so don't rely on them. There's also an anomaly in the USA listing for the Aleutian Islands, given as 10 hours — but we'll discuss that later. Finally, let's talk about Summer Time, or Daylight Saving Time — DST, as it's called in the USA. Some countries in all lists may carry Summer Time or DST in the summer months. This is normally indicated by an asterisk * against the country listed. Summer time is normally 1 hour in advance of Standard Time. So if the Standard Time is, say, UTC minus 5, then in summer it becomes UTC minus 4 — one hour ahead of what it normally is. That's the core of it. Let's look at the International Date Line figure to see how these corrections tie together geographically.