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DGCA Air Navigation · 121 questions

Simple Navigation Maths: DGCA Air Navigation Questions and Answers

121 practice questions on Simple Navigation Maths with answers and explanations, plus the key concepts and formulas, from the TrueHeading question bank.

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About this topic

Use this page to revise Simple Navigation Maths for the DGCA Air Navigation paper. Below are the key ideas first, then 12 practice questions with answers and explanations, picked from the 121 questions in the TrueHeading bank for this topic.

In short: Rate of climb in ft/min depends on gradient and ground speed.

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Key concepts: Simple Navigation Maths

4 ideas to know cold.

Convert a climb or descent gradient into a rate of climb.

Rate of climb in ft/min depends on gradient and ground speed.

ROC(ft/min)≈GS(kt)×gradient(%)×1.013ROC(\text{ft/min})\approx GS(\text{kt})\times\text{gradient}(\%)\times 1.013
  • 5 % gradient at 120 kt ≈ 600 ft/min
  • ft per NM = ROC ÷ GS × 60
γheightgainhorizontal distanceclimb pathGradient % = height ÷ distance × 100ft per NM = ROC ÷ GS × 60

Gradient in percent from the angle?

Percent gradient is 100 × tan of the angle.

gradient (%)=100tan⁡θ\text{gradient}\ (\%)=100\tan\theta
  • 3° ≈ 5.2 % ≈ 318 ft per NM
  • 1° ≈ 1.75 % ≈ 106 ft per NM

Fuel, time and distance: how do you solve “how much fuel for this leg”?

Time first, then fuel.

fuel=fuel flow×distanceGS\text{fuel}=\text{fuel flow}\times\frac{\text{distance}}{GS}
  • Use the leg’s ground speed, not TAS
  • Add reserve according to the rules in the question

How do you find time, distance and speed quickly?

Use the triangle: Distance = Speed × Time.

D=S×TD=S\times T
  • Minutes = distance × 60 / groundspeed
  • Mach × 10 ≈ NM per minute at cruise (M 0.8 ≈ 8 NM per min)
  • Fuel required = flow × time

Practice questions: Simple Navigation Maths

Tap “Show answer” after you have tried each one.

Q1What is the time to fly 1490 NM at a groundspeed of 330 kt?

  1. 06h 19min
  2. 07h 13min
  3. 03h 23min
  4. 04h 31min
Show answer

Answer: D. 04h 31min

Time = 1490 ÷ 330 h = 271 min.

Q2What is the time to fly 990 NM at a groundspeed of 290 kt?

  1. 03h 45min
  2. 03h 25min
  3. 04h 16min
  4. 02h 03min
Show answer

Answer: B. 03h 25min

Time = 990 ÷ 290 h = 205 min.

Q3What is the time to fly 1030 NM at a groundspeed of 360 kt?

  1. 02h 52min
  2. 02h 09min
  3. 02h 34min
  4. 01h 43min
Show answer

Answer: A. 02h 52min

Time = 1030 ÷ 360 h = 172 min.

Q4An aircraft flies at a groundspeed of 280 kt for 33 minutes. The distance covered is:

  1. 177 NM
  2. 216 NM
  3. 154 NM
  4. 116 NM
Show answer

Answer: C. 154 NM

Distance = 280 × 33/60 = 154 NM.

Q5An aircraft flies at a groundspeed of 330 kt for 66 minutes. The distance covered is:

  1. 454 NM
  2. 363 NM
  3. 327 NM
  4. 508 NM
Show answer

Answer: B. 363 NM

Distance = 330 × 66/60 = 363 NM.

Q6An aircraft flies at a groundspeed of 120 kt for 63 minutes. The distance covered is:

  1. 126 NM
  2. 158 NM
  3. 113 NM
  4. 76 NM
Show answer

Answer: A. 126 NM

Distance = 120 × 63/60 = 126 NM.

Q7An aircraft covers 320 NM in 90 minutes. Its groundspeed is:

  1. 128 kt
  2. 192 kt
  3. 181 kt
  4. 213 kt
Show answer

Answer: D. 213 kt

GS = 320 ÷ 90 × 60 = 213 kt.

Q8An aircraft covers 180 NM in 160 minutes. Its groundspeed is:

  1. 61 kt
  2. 68 kt
  3. 74 kt
  4. 78 kt
Show answer

Answer: B. 68 kt

GS = 180 ÷ 160 × 60 = 68 kt.

Q9The distance between two points is 590 nm. At a ground speed of 150 kt the time en route is:

  1. 3 h 56 min
  2. 4 h 31 min
  3. 3 h 47 min
  4. 4 h 04 min
Show answer

Answer: A. 3 h 56 min

Time = distance ÷ speed = 590 ÷ 150 = 3.93 h = 3 h 56 min.

Q10An aircraft flies for 1 h 30 min at a ground speed of 440 kt. The distance covered is:

  1. 792 nm
  2. 396 nm
  3. 528 nm
  4. 660 nm
Show answer

Answer: D. 660 nm

Distance = GS × time = 440 × 90/60 = 660 nm.

Q11200 nm are flown in 2 h 30 min. The average ground speed is:

  1. 70 kt
  2. 80 kt
  3. 99 kt
  4. 92 kt
Show answer

Answer: B. 80 kt

GS = distance ÷ time = 200 ÷ 2.500 h ≈ 80 kt.

Q12How far does an aircraft with a ground speed of 300 kt travel in one minute?

  1. 50 nm
  2. 5 nm
  3. 2 nm
  4. 10 nm
Show answer

Answer: B. 5 nm

300 kt = 300 nm per 60 min = 5 nm per minute.

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