We depart at 2200 UTC on 4 May, and the flight time is 0645 — that's 6 hours… — Page 414, Lesson 369

I want to walk you through the worked answers to Questions 4 through 10 in this time-conversion exercise, and then we'll look at the Air Almanac extract that supports them. This is the heart of practical time navigation — taking a departure or arrival in Standard Time, converting to UTC, adding flight time, and converting back. Let's start with Question 4. We depart at 2200 UTC on 4 May, and the flight time is 0645 — that's 6 hours 45 minutes. Adding them gives an arrival of 0445 UTC on 5 May. Now we convert that UTC arrival into Local Mean Time, or LMT. The "Arc to time" step of 0804 means we convert an arc — a longitude difference — into time. Here, 8 hours 4 minutes is added, giving 1249 LMT on 5 May. Then we apply the Standard Time correction of plus 0800 — that's the +8 hours for the Philippines — and we arrive at 1245 ST. Notice the LMT and ST differ by 4 minutes; that's the difference between the local meridian time and the standard meridian time for that zone. Question 5 is a comparison. Bangkok at 101°E is 0644 later than UTC. San Francisco at 122°25'W is 0810 earlier than UTC. The total difference is 1454 — that's 14 hours 54 minutes — and Bangkok is later than San Francisco. So when it's noon in Bangkok, it's still the previous evening in San Francisco. Question 6 introduces Daylight Saving Time, abbreviated DST. We depart at 0915 New York Summer Time. The ST correction is minus 0400 — subtract 4 hours — giving a departure of 1315 UTC. Flight time is 0525, so arrival is 1840 UTC. Now the ST correction is minus 0800 — subtract 8 hours for British Columbia — giving an arrival of 1040 ST. Note the sign change: New York in summer is UTC minus 4, British Columbia is UTC minus 8. Question 7 works backward from arrival. Arrival time is 1835 ST in Hong Kong. The ST correction is minus 08, giving 1035 UTC. The scheduled time is 2140 — that's the scheduled arrival in UTC? No — let me read it carefully. Schedule time 2140, departure 1255 UTC previous day. The ST correction is plus 0100, giving a departure of 1355 ST in Rome. So we have a scheduled time of 2140, a departure of 1255 UTC the previous day, and we convert that departure to Rome Standard Time by adding 1 hour. Question 8: Departure 0930 ST on 8 May in New South Wales. ST correction is 10 — add 10 hours — giving 2330 UTC on 7 May. Flight time 0950, arrival 0920 UTC on 8 May. Then "Arc to time" of minus 1031 — subtract 10 hours 31 minutes — giving arrival of 2249 LMT on 7 May. So the local mean time at the destination is actually on the previous day relative to the UTC arrival. Question 9: Departure 2300 ST in Hawaii on 10 May. ST correction plus 1000, giving 0900 UTC on 11 May. Flight time 1020, arrival 1920 UTC on 11 May. ST correction plus 1000 again, giving arrival 0520 ST on 12 May. So you cross the date line and arrive the next day. Question 10: Departure 2000 ST in New York on 16 Feb. ST correction plus 0500, giving 0100 UTC on 17 Feb. Flight time 0745, arrival 0845 UTC on 17 Feb. ST correction 0100 — add 1 hour — giving arrival 0945 ST in Madrid on 17 Feb. Now, the Air Almanac extract. This is the standard times table, corrected to June 1988. It's in two lists — List 1 is places fast on UTC, mainly east of Greenwich. The times given should be added to UTC to give Standard Time, and subtracted from Standard Time to give UTC. So for New South Wales, the entry is 10 — that's the +10 hours we used in Question 8. For the Philippines, we used +8, which matches Hong Kong at 08. For British Columbia, we used minus 8 — that's in the other list, places slow on UTC, west of Greenwich. Notice the fractional hours: Afghanistan is 04 30, meaning 4 hours 30 minutes. India is 05 30. Burma is 06 30. The Chatham Islands are 12 45. And Indonesia is split into three zones — 07, 08, and 09 — depending on which islands. Australia is also split: New South Wales, Queensland, Tasmania, and Victoria are 10; Northern Territory and South Australia are 09 30; Western Australia is 08. The asterisks mark places that observe daylight saving time — you see them on Cyprus, Albania, Australia's New South Wales, and many European countries. So when you see an asterisk, you know that during summer months the actual offset may be one hour more than the listed value. That's the complete set of worked answers and the standard time table. The key skill is keeping the sign of the correction straight — fast on UTC means add to get ST, subtract to get UTC.