Avielevate / DGCA CPL papers / Air Navigation / Time
Time — DGCA CPL Air Navigation
Chapter GN05 of the Air Navigation paper. 30 practice questions in the Avielevate bank, every one with its answer key, filterable into a timed set on this chapter alone.
What this chapter covers
The learning objectives we file Time questions under, and how many sit behind each. These come straight out of the bank and are regenerated whenever it changes — they are what is there today, not a claim.
| Learning objective | In the bank |
|---|
| __GEN__ General | 30 questions |
Sample Time questions, answered and explained
Real questions from this chapter, with the answer marked and the reasoning written out — the same explanations you get inside the app.
0213046 · Time
At longitude 160°E (LMT = UTC + 10 h 40 min), what is the difference between zone time and LMT?
- AZone time will be ahead of LMT by 20 min
- BZone time will be ahead of LMT by 40 min
- CLMT will be ahead of ZT by 20 min
Why that is the answer
Using the exact LMT of every meridian would give every town a slightly different clock. So the world is divided into **time zones**, each 15° of longitude wide (one hour). Every place in a zone keeps the time of the zone's **central meridian**, which is a multiple of 15°. The zone reaches 7°30′ either side of that meridian.
Look at the diagram. The **zone number** is the longitude ÷ 15, rounded to the nearest whole number. Zone time (ZT) is UTC plus the zone number in the east, and UTC minus the zone number in the west.
**Local mean time** (LMT) is the exact time for the place's own meridian. So zone time and LMT agree only on the central meridian; elsewhere they differ by 4 minutes for each degree between the place and the central meridian.
**Apply it**
LMT: 160° × 4 min = 640 min = 10 h 40 min, so LMT = UTC + 10 h 40 min (as given).
Zone number: 160 ÷ 15 = 10.67, which rounds to 11. The zone's central meridian is 165°E, so ZT = UTC + 11 h.
Difference: 11 h 00 min − 10 h 40 min = 20 min. (Check: 165° − 160° = 5° × 4 min = 20 min.) The central meridian is further east, so its time is later.
So **zone time is ahead of LMT by 20 minutes**.
0213058 · Time
The times of sunrise, sunset, and morning and evening twilight given in the Air Almanac are stated in:
- Aare stated in UTC.
- Bare stated in standard time.
- Care stated in LMT.
Why that is the answer
Sunrise and sunset happen at roughly the same **local** time at every place on the same latitude.
So the Air Almanac tabulates these times in **Local Mean Time (LMT)** against latitude only.
To use them, you look up the LMT for your latitude and then convert it to UTC using your longitude (4 minutes for every 1° of longitude).
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Frequently asked
How many Time questions are there for the DGCA CPL Air Navigation paper?
Avielevate's bank carries 30 published Time questions for Air Navigation, mapped across 1 learning objective. Every one has its answer key, and explanations are being written across the whole bank.
How much of the Air Navigation paper is Time?
The DGCA does not publish a per-chapter breakdown of its papers, so nobody can honestly tell you — and we will not guess. What we can tell you is what students who have just sat a paper reported meeting, which is measured rather than rumoured: that is the exam recall report inside the app.
What is the best way to revise Time?
Sit a short timed set on this chapter alone, tag how sure you were of each answer, then drill the two that actually leak marks: the ones you got right while guessing, and the ones you got wrong while confident. Avielevate does that tagging for you and puts anything you got wrong back in front of you on a spaced schedule.
The rest of the Air Navigation paper
One account covers every chapter of every paper.
← All Air Navigation chapters · All six DGCA CPL papers