The idea, step by step
Convert before subtracting
A departure time and an arrival time in different zones cannot be subtracted directly. Convert both to UTC or to the same local zone first. Then find the elapsed time. Keep any day changes in the calculation.
For a departure at 10:40 from UTC+2 and arrival at 16:10 in UTC+5 on the same local day, UTC readings are 08:40 and 11:10. The flight lasts 2 hours 30 minutes. The local clocks appear 5 hours 30 minutes apart, but 3 hours of that gap comes from their zones.
Build a feasible schedule
A usable schedule satisfies every stated constraint: the travelling duration, the time-zone conversion, the day, and any check-in or transfer minimum. Estimate first so that a wildly wrong answer is easier to notice. Then calculate each stage.
Finally, explain what your answer means. Arriving before a local departure clock reading can be possible when travelling west, but a negative elapsed duration on a single reference clock is not. A connection with too little transfer time fails even if its final arrival would be attractive.
A common trap
Subtract local arrival from local departure to get flight duration even when the zones differ.
Instead: First convert both to the same clock. Clock offsets are not part of the time spent travelling.
See the thinking
Find a flight duration
A flight leaves at 10:40 from UTC+2 and arrives at 16:10 in UTC+5 on the same local day. Find its duration.
- Departure UTC=10:40−2 h=08:40.
- Arrival UTC=16:10−5 h=11:10.
- 11:10−08:40=2 h 30 min.
Predict arrival
A flight leaves at 11:25 from UTC+9:30 and lasts 2 h 45 min. Give the arrival time in a town at UTC+8.
- Departure UTC=11:25−9 h 30 min=01:55.
- After 2 h 45 min, UTC arrival is 04:40.
- Add 8 h for the destination.
Check your understanding
A 2-hour flight departs UTC+3 at 09:00. What is arrival time at UTC+1?
Show answer
09:00, on the same day.
UTC departure is 06:00, UTC arrival is 08:00, and destination time is 09:00. The flight still lasts 2 hours.
Your turn
6 questions · 12 marks · Work at your own pace.
Read the questions online
- A trip departs 08:30 at UTC+2 and arrives 13:00 at UTC+4 on the same day. Find its duration.2 marks
- A 3-hour flight leaves 14:20 at UTC+5. Give arrival time at UTC+2.2 marks
- A 2 h 20 min flight leaves 22:50 Friday at UTC+1. Find arrival at UTC+3.2 marks
- A plane lands at 10:15. The next flight leaves 11:05, and the minimum connection is 55 min. Does it work?2 marks
- A 90-minute trip leaves at 23:20 Tuesday in one zone. The destination is 2 hours behind. Give arrival day/time.2 marks
- Local departure is 12:00 at UTC+4. Local arrival is 14:00 at UTC+1 on the same day. A student claims the journey took 2 hours. Check the claim.2 marks
Read the worked solutions
Equivalent correct methods earn the corresponding marks. Include units where asked.
- A trip departs 08:30 at UTC+2 and arrives 13:00 at UTC+4 on the same day. Find its duration.2 marks
UTC departure 06:30; UTC arrival 09:00.
Difference=2 h 30 min.
2 h 30 min. - A 3-hour flight leaves 14:20 at UTC+5. Give arrival time at UTC+2.2 marks
Departure is 09:20 UTC. Add 3 h to get 12:20 UTC. Add 2 h for the destination: 14:20.
14:20, same day. - A 2 h 20 min flight leaves 22:50 Friday at UTC+1. Find arrival at UTC+3.2 marks
Departure is 21:50 Friday UTC. After 2 h 20 min it is 00:10 Saturday UTC. Add 3 h for the destination: 03:10 Saturday.
Saturday 03:10. - A plane lands at 10:15. The next flight leaves 11:05, and the minimum connection is 55 min. Does it work?2 marks
11:05−10:15=50 min<55 min.
No; only 50 min is available, 5 min short. - A 90-minute trip leaves at 23:20 Tuesday in one zone. The destination is 2 hours behind. Give arrival day/time.2 marks
On the origin clock, arrival is Wednesday 00:50.
Subtract 2 h for the destination: Tuesday 22:50.
Tuesday 22:50. - Local departure is 12:00 at UTC+4. Local arrival is 14:00 at UTC+1 on the same day. A student claims the journey took 2 hours. Check the claim.2 marks
Departure is 08:00 UTC; arrival is 13:00 UTC.
13:00−08:00=5 h.
It took 5 hours, not 2.
Curriculum reference & lesson scope
Australian Curriculum v9 and SA Curriculum Mathematics
Converting 12-/24-hour time; elapsed time across midnight; timetables and journeys; time-zone differences; date changes; checking real-world scheduling answers.
Official curriculum source ↗