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ILS (Instrument Landing System) — DGCA CPL Air Navigation
Chapter GN31 of the Air Navigation paper. 57 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 ILS (Instrument Landing System) 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 | 57 questions |
Sample ILS (Instrument Landing System) 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.
0239113 · ILS (Instrument Landing System)
On a standard 3° glide slope, the DME reads 1.9 nm and the glide slope needle shows 2 dots below centre on a four-dot indicator. What should the radio altimeter read?
- A675
- B795
- C855
Why that is the answer
The glide slope needle shows how far the aircraft is above or below the glide slope, as an **angle**. The needle (the diamond) shows where the glide slope is, relative to you. Look at the diagram.
**Step 1: read the needle**
The needle is **below** centre, so the glide slope is below you: the aircraft is **above** the glide slope.
Full-scale deflection is about **0.7°**. On a four-dot indicator there are 2 dots each side, so 2 dots = full scale = 0.7°.
The aircraft is on a line 3° + 0.7° = **3.7°** from the threshold.
**Step 2: distance in feet**
1.9 NM × 6,080 = 11,552 ft
**Step 3: height on a 3.7° line**
tan 3.7° = 0.0647, so 11,552 × 0.0647 ≈ 747 ft
**Step 4: add the threshold crossing height**
A standard glide slope crosses the threshold at **50 ft**, so add it: 747 + 50 ≈ 797 ft.
Assuming the ground under the approach is level with the threshold, the radio altimeter (which measures height above the ground below) reads about **795** ft.
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Frequently asked
How many ILS (Instrument Landing System) questions are there for the DGCA CPL Air Navigation paper?
Avielevate's bank carries 57 published ILS (Instrument Landing System) 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 ILS (Instrument Landing System)?
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 ILS (Instrument Landing System)?
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