Avielevate / DGCA CPL papers / Air Navigation / Measurement/ Determination of Temperature
Measurement/ Determination of Temperature — DGCA CPL Air Navigation
Chapter GN11 of the Air Navigation paper. 60 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 Measurement/ Determination of Temperature 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 | 60 questions |
Sample Measurement/ Determination of Temperature 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.
0219083 · Measurement/ Determination of Temperature
At FL 120 (ISA temperature), the CAS is 200 kt, the track is 222°(M), the heading is 215°(M) and the variation is 15°W. It takes 21 minutes to fly 105 nm. What is the wind velocity?
- A050°(T) / 75 kt.
- B050°(T) / 70 kt.
- C050°(T) / 50 kt.
Why that is the answer
The aircraft points along its **heading** at its **TAS**, but the wind pushes it, so over the ground it moves along its **track** at its **groundspeed (GS)**. Look at the diagram: the wind is the gap between these two arrows. Knowing heading/TAS and track/GS lets you work out the wind.
Step 1: TAS. At FL120 in ISA the density ratio is about 0.693, so TAS = 200 ÷ √0.693 = 200 ÷ 0.833 = 240 kt (a flight computer gives the same).
Step 2: GS = distance ÷ time = 105 NM ÷ (21 ÷ 60) h = 105 ÷ 0.35 = 300 kt
Step 3: Drift = track − heading = 222° − 215° = 7° right
Step 4: True heading = 215° − 15°W = 200°(T)
Now split the GS into a part along the heading and a part across it.
Step 5: Along: 300 × cos 7° = 297.8 kt. That is more than the TAS, so the tailwind = 297.8 − 240 = 57.8 kt
Step 6: Across: 300 × sin 7° = 36.6 kt of crosswind. The drift is right, so the wind blows from the left.
Step 7: Wind speed = √(57.8² + 36.6²) = √4,681 = 68 kt, about 70 kt
Step 8: Angle from the tail = tan⁻¹(36.6 ÷ 57.8) = about 32°
Step 9: The tail points to 020°. Moving 32° towards the left side of the aircraft gives 020° + 32° = 052°, about 050°(T)
The wind velocity is **050°(T)/70 kt**.
0219096 · Measurement/ Determination of Temperature
What does CAS represent?
- AEAS (Equivalent Airspeed) corrected for position error and compressibility error
- BIAS corrected for position error and instrument error
- CIAS corrected for density error and position error
Why that is the answer
Look at the diagram: the first step from the dial reading (**IAS**) towards the true speed gives **CAS (calibrated airspeed)**. Two kinds of error are removed in this step:
- **Instrument error**: small manufacturing imperfections and friction inside the instrument itself.
- **Position (pressure) error**: the static ports sense a slightly wrong pressure because of the airflow around the aircraft.
So CAS represents **IAS corrected for position error and instrument error**.
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Frequently asked
How many Measurement/ Determination of Temperature questions are there for the DGCA CPL Air Navigation paper?
Avielevate's bank carries 60 published Measurement/ Determination of Temperature 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 Measurement/ Determination of Temperature?
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 Measurement/ Determination of Temperature?
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