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Aviation in some form is everywhere we go around the world. Essential knowledge for every flight is understanding the time. For local flights this is easy, but as soon as we venture further away and we need to read weather forecasts and understand when control zone restrictions etc.. apply, it gets more complicated. As flights get longer they may begin to cross over various time zone boundaries, meaning the time we set on our watch when we departed is no longer the local time. The further we fly the greater the difference in the time zone between when we departed and when we land. In particular this makes things like reading the weather forecast (TAF) and working out the Time Of First Light/Time Of Last Light an issue if we have a different time zone between departure and destination. To overcome this significant issue, aviation worldwide only uses a single time zone. The aviation world sets its clocks to UTC - Universal Time Coordinated. Aviators often refer to UTC as 'Z' or Zulu Time, because years ago Nautical Time Zones had letters as designators and Z was applied to the Greenwich Time Zone, which is historically the origin of world time zones. Greenwich is located just to the south east of central London UK. At Greenwich there is the very old Royal Observatory where the Prime Meridian of 000 Degrees Longitude runs. You can stand with one foot either side of the line and be in the eastern and western hemispheres at the same time. More importantly we are standing at the point world time is set from. Local time zones are referenced to UTC depending if they are in the eastern or western hemispheres. To the east of Greenwich time zones are ahead of the current UTC time. The eastern states of Australia are usually UTC+10 hours which is Eastern Standard Time (EST), with daylight saving making the difference UTC+11 hours, known as Eastern Daylight Time (EDT) in some places. Central Australia is usually UTC+9:30 known as Central Standard Time (CST), with daylight saving making the difference UTC+10:30, known as Central Daylight Time (CDT) in some places. Western Australia is UTC+8 known as Western Standard Time (WST) with no daylight savings periods. There is another not well known unoffical time zone in the far south east corner of WA near the SA border which is UTC+8:45 called Australian Central Western Standard Time (ACWST). It will not appear in CASA exams. For aviation purposes, we often need to convert our local time zone back to UTC or UTC to our local time zone. That conversion can be simple or it can be hard, depending entirely on the actual time we are converting. When you create new questions with this RQG, the process will be explained in more detail on a step by step basis, however for a general understanding of the process here is a brief explanation. We normally write date and time as a six figure group. So on the 17th of the month 15:35 UTC would be written as 171535 UTC. If we want to convert 171535 UTC to WST we first break it down into Date Hours Minutes, so we get 17 15 35 UTC. To convert to WST in this case is easy. We are going forwards in time and only adding hours, so 15 hours + 8 hours = 23 hours. The date and minutes remain the same so the final outcome is 172335 WST. But if we want to convert the 171535 UTC to CST, it gets a bit tricky. 17 15 35 UTC + 9 hours and 30 minutes = 17 24 65 CST. Mmmmm...? We need to make some changes. We always look at the minutes first, so let's write it down like a maths equation. 17 15 35 CST + 09 30 Conversion to CST = 17 24 65 CST We need to convert the 65 minutes into hours and minutes, by taking 60 minutes from the minutes total and adding 1 hour in the hour total. So 24:65 CST becomes 25:05 CST. 17 15 35 CST + 09 30 Conversion to CST = 17 25 05 CST That still doesn't look right as there are only 24 hours in a day, so next we sort out the hours. To sort out the hours we need to convert 24 hours from the hours total into a whole day. We take 24 hours from the hour total to get 01:05 CST and then add a whole day to the date, so the 17th becomes the 18th. We started with 171535 UTC, added 9 hours and 30 minutes to get 17 24 65 CST, then changed the excess minutes to hours and the excess hours into a whole day, so the final six figure date time group is 180105 CST 17 15 35 CST + 09 30 Conversion to CST = 18 01 05 CST Final answer is 180105 CST The reverse process applies if converting 180105 CST back to UTC.. and it can get tricky. First once again break the group into Date Hours Minutes, so we get 18 01 05 CST. Now we need to go back in time by subtracting 9 hours and 30 minutes. Again write it down like a maths equation. 18 01 05 CST - 09 30 Conversion to UTC Can we directly take 30 minutes from 05 minutes? No! So in reverse this time, convert 1 hour into 60 minutes. The minutes go from 05 to 65, and the hours goes back from 01 to 00 and we get: 18 00 65 CST - 09 30 Conversion to UTC Can we directly take 09 hours from 00 hours? No! So in reverse this time, convert 1 whole day hour into 24 hours. The hours go from 00 to 24, and the date goes back from 18th to the 17th and we get: 17 24 65 CST - 09 30 Conversion to UTC Now we can directly take the conversion hours from the CST hours and the conversion minutes from the CST minutes, so complete the equation. 17 24 65 CST - 09 30 Conversion to UTC = 17 15 35 UTC Final answer is 171535 UTC The RQG does some calculations like basic maths problems as described above, while also at times doing the calculations as if you do steps mentally before writing down the progressive outcome, so you will learn over time to eventually do the whole conversion in your head. Now you can go practice as many different time zone conversions as you like via the RQG, and yes eventually you will be able to do even the most complicated calculations in your head without needing to write down a single number. Really you will. You just need practice. This knowledge will be used in a practical way reading TAFs, calculating Time Of First Light and Time Of Last Light, and converting ETA/ETD to match TAF validity during your studies. Fly Safe Wazza |