Air Navigation marks are usually lost to process errors, not missing knowledge: a wind correction applied the wrong way, a time zone forgotten, a unit mixed up.
This guide gives you worked examples for the four core skill areas (time-speed-distance, wind correction, chart plotting and flight planning), a list of the mistakes that cost marks, a daily practice routine, and 12 original practice questions with answers. It is a companion to our main DGCA Air Navigation guide, which covers the syllabus, books and study plan.
The short version:
Sketch every problem, estimate before you calculate, write units on every line, and check direction logic last. Log every error with its cause and practise daily, even for 30 minutes, with a timer.
Key Takeaways
- Sketch every problem: A rough diagram prevents direction errors.
- Estimate before you calculate: The 1-in-60 rule and simple fractions give you a check.
- Write units on every line: Nautical miles, kilometres, litres, kilograms and hours get mixed up easily.
- Check direction logic last: Ask whether this heading makes sense for this wind.
- Log every error with its cause: Concept, calculation, misread or time pressure.
- Practise daily, even for 30 minutes, with a timer.
Quick Navigation
- How This Differs from Our Main Air Navigation Guide
- The Seven Mistakes That Cost the Most Marks
- A Reliable Method for Every Calculation
- Worked Examples: Time, Speed and Distance
- Worked Examples: True, Magnetic and Compass Headings
- Worked Examples: Wind Correction and Ground Speed
- Worked Examples: Chart Plotting and Scale
- Worked Examples: Dead Reckoning and the 1-in-60 Rule
- Worked Examples: Flight Planning, Fuel and Point of No Return
- A Daily Practice Routine
- 12 Practice Questions
- Answers and Explanations
- How The Pilot's Compass Teaches Air Navigation
- Frequently Asked Questions
How This Differs from Our Main Air Navigation Guide
| Our DGCA Air Navigation guide | This practice guide |
|---|---|
| Syllabus overview and topic difficulty | Worked calculations with numbers |
| Book recommendations | Mistake patterns and checking habits |
| An 8-week study plan | A daily practice routine and 12 practice questions |
Use the main guide to learn what to study, and this one to practise how to calculate. For the full list of subjects, see DGCA CPL subjects.
Note: The questions here are original practice material, not DGCA exam questions.
The Seven Mistakes That Cost the Most Marks
| # | Mistake | Example | How to avoid it |
|---|---|---|---|
| 1 | Wind correction applied the wrong way | Wind from the left, but you add the correction instead of subtracting | Draw the wind arrow. Wind from the left means turn left, so heading is less than track |
| 2 | True, magnetic and compass mix-ups | Adding East variation when going from true to magnetic | Use a memory aid and write each step: TVMDC, variation then deviation |
| 3 | Unit confusion | Using kilometres in a nautical-mile formula, or litres where kilograms are needed | Write the unit beside every number and convert before calculating |
| 4 | Time zone errors | Forgetting that IST is UTC plus 5 hours 30 minutes | Convert everything to one time standard first |
| 5 | Early rounding | Rounding a wind correction to a whole number before using it in the next step | Carry one extra decimal and round at the end |
| 6 | Misreading the question | Calculating ground speed when the question asks for time | Underline what is being asked before you start |
| 7 | Using the wrong meridian or scale | Measuring track at the departure meridian on a chart where meridians converge | Learn the rule for your chart type and apply it every time |
A Reliable Method for Every Calculation
Use these five steps on every problem until they become automatic.
- Sketch. Draw the track, heading and wind, even if rough.
- Write the knowns and units. Mark what the question asks for.
- Estimate. Use a rough fraction or the 1-in-60 rule to predict the answer.
- Calculate. Use the flight computer, calculator or formula permitted in your exam.
- Check. Does the answer agree with your estimate and with common sense?
If steps 3 and 4 disagree by a large margin, stop and look for a direction, unit or reading error before you move on.
Worked Examples: Time, Speed and Distance
Example 1. An aircraft has a ground speed of 126 kt and must fly 273 NM. How long does the leg take?
- Time = Distance ÷ Ground speed = 273 ÷ 126 = 2.1667 hours
- 0.1667 hours is 10 minutes, so the time is 2 hours 10 minutes
Check by estimate: 126 kt is about 2.1 NM a minute. 273 ÷ 2.1 is about 130 minutes. That matches.
Example 2. If the departure is at 0430 UTC, what is the ETA in IST?
- ETA = 0430 + 2:10 = 0640 UTC
- IST = UTC + 5:30, so ETA = 1210 IST
Example 3. Convert 80 US gallons to litres. (1 US gallon is about 3.785 litres.)
- 80 × 3.785 = 302.8 litres
Common slip: mixing US gallons with Imperial gallons. Read the question carefully for which one is used.
Worked Examples: True, Magnetic and Compass Headings
Remember the sequence True, Variation, Magnetic, Deviation, Compass (TVMDC). Going from True toward Compass, apply variation first, then deviation. Useful memory aids:
- Variation East, Magnetic least. East variation means magnetic is less than true.
- Variation West, Magnetic best (greatest).
- Deviation East, Compass least. Deviation West, Compass best.
Example 4. True heading 090, variation 3 degrees West, deviation 2 degrees East. Find the compass heading.
- Magnetic = True + West variation = 090 + 3 = 093
- Compass = Magnetic − East deviation = 093 − 2 = 091
Example 5. True track 075, variation 2 degrees East. Find the magnetic track.
- Magnetic = True − East variation = 075 − 2 = 073
Worked Examples: Wind Correction and Ground Speed
The wind triangle links track, heading, wind and speeds. Two quick tools help:
- Exact formula: Wind correction angle (WCA) = arcsin (wind speed × sin(wind angle) ÷ TAS)
- 1-in-60 estimate: WCA is approximately (wind speed × sin(wind angle) ÷ TAS) × 60, which is accurate for small angles
The wind angle is the angle between the track and the direction the wind is blowing from.
Example 6. TAS 120 kt, required track 360, wind 270 at 30 kt. Find the heading and ground speed.
- Wind angle = 90 degrees. The wind blows from the left (west) of a northbound track.
- Estimate by the 1-in-60 rule: WCA is about (30 ÷ 120) × 60 = 15 degrees.
- Exact: arcsin (30 ÷ 120) = arcsin 0.25 = 14.5 degrees.
- Wind from the left pushes the aircraft right, so point left of track: heading = 360 − 14.5 = about 345.5 degrees.
- With a pure crosswind, ground speed = square root of (120² − 30²) = about 116 kt.
Check: heading is left of track for a wind from the left, and ground speed is a little below TAS. Both make sense.
Example 7. TAS 150 kt, track 090, wind 040 at 40 kt. Find the heading and ground speed.
- Wind angle = 090 − 040 = 50 degrees, wind from the left of the track.
- WCA = arcsin (40 × sin 50 ÷ 150) = arcsin (0.2043) = about 11.8 degrees.
- Heading = track − WCA = 090 − 11.8 = about 078 degrees.
- Headwind component = 40 × cos 50 = about 25.7 kt.
- Ground speed = 150 × cos 11.8 − 25.7 = 146.9 − 25.7 = about 121 kt.
Takeaway: when the wind is ahead of the beam, expect a headwind component and a ground speed below TAS.
Worked Examples: Chart Plotting and Scale
On a 1:1,000,000 chart (a common scale for world aeronautical charts), 1 cm on the chart equals 10 km on the ground, which is about 5.4 NM. Equivalent shortcut: 10 NM is about 1.85 cm.
Example 8. You measure 7.4 cm along your track on a 1:1,000,000 chart. How far is that in nautical miles?
- 7.4 cm × 10 km per cm = 74 km
- 74 ÷ 1.852 = about 40 NM
Example 9. How much does a 2 degree track error matter?
- By the 1-in-60 rule, 1 degree error gives about 1 NM off track for every 60 NM flown.
- Over 100 NM, 2 degrees gives about (2 × 100) ÷ 60 = 3.3 NM (the exact trigonometric value is about 3.5 NM).
This is why careful plotting matters. A small angular error becomes a real distance error over a long leg. Chart habits that save marks:
- On Lambert conformal charts, true track changes along a route because meridians converge. Measure the track at the mid-point meridian of the leg.
- Take variation from the chart's isogonals near the leg, not from memory.
- Use a sharp pencil and the correct scale, and check the protractor's reading direction before you read an angle.
- Convert true track to magnetic only after plotting, and label each value as true, magnetic or compass.
Worked Examples: Dead Reckoning and the 1-in-60 Rule
The 1-in-60 rule lets you work out heading corrections in your head.
Example 10. You are flying a 120 NM leg. After 40 NM you find you are 4 NM left of track. Remaining distance is 80 NM. What heading change gets you to the destination?
- Track error angle = (off-track distance ÷ distance flown) × 60 = (4 ÷ 40) × 60 = 6 degrees (you have been drifting left of track).
- Closing angle = (off-track distance ÷ distance to go) × 60 = (4 ÷ 80) × 60 = 3 degrees.
- Total correction = 6 + 3 = 9 degrees toward the track. Because you are left of track, turn right by 9 degrees.
Why this works: the first 6 degrees stops the drift (it cancels the error you have been flying), and the extra 3 degrees makes you converge on the destination.
Worked Examples: Flight Planning, Fuel and Point of No Return
Example 11. Fuel for a leg. Distance 330 NM, TAS 120 kt with a 10 kt headwind component, fuel flow 40 litres an hour, taxi fuel 5 litres, reserve 45 minutes at cruise flow. How much fuel is required?
- Ground speed = 120 − 10 = 110 kt.
- Time = 330 ÷ 110 = 3.0 hours.
- Trip fuel = 3.0 × 40 = 120 litres.
- Reserve = 0.75 × 40 = 30 litres.
- Total = 5 + 120 + 30 = 155 litres.
Note: real-world reserves and contingency come from DGCA requirements and the data given in the exam question. Use the figures in the question, and learn the rules from the Air Regulations syllabus.
Example 12. Point of no return (PNR). Safe endurance is 4 hours. Ground speed out is 100 kt, and ground speed home is 140 kt. Find the time and distance to the PNR.
- Time to PNR = Endurance × GS home ÷ (GS out + GS home) = 4 × 140 ÷ 240 = 2 hours 20 minutes
- Distance = 2.333 hours × 100 kt = 233 NM
Check: 233 NM back at 140 kt takes 1 hour 40 minutes, so the total is 2:20 + 1:40 = 4:00.
Example 13. Descent planning (rule of thumb). A 3 degree descent path is roughly 300 ft per NM. To lose 6,000 ft you need about 20 NM. The required rate of descent is roughly 5 × ground speed, so at 120 kt, about 600 feet per minute.
Latitude and longitude distance: 1 degree of latitude is 60 NM. For longitude, departure = change of longitude (degrees) × 60 × cos(latitude).
A Daily Practice Routine
A realistic 45 to 60 minute session:
| Minutes | Activity |
|---|---|
| 5 | Warm-up: five quick mental estimates (time, distance, 1-in-60) |
| 20 | Two or three full problems in the method above, timed |
| 10 | One chart-plotting or time-zone problem |
| 10 | Review: check each answer against its estimate |
| 5 | Log mistakes with their cause |
A weekly pattern also helps:
| Day | Focus |
|---|---|
| Monday | Time, speed and distance, unit conversions |
| Tuesday | True, magnetic and compass conversions |
| Wednesday | Wind triangle and flight computer |
| Thursday | Plotting and scale |
| Friday | Dead reckoning and the 1-in-60 rule |
| Saturday | Flight planning and fuel |
| Sunday | Mixed timed set and error review |
If you are in the final month before an exam, merge this with our exam preparation guide, which shows where navigation fits across all subjects.
12 Practice Questions
Try each one using the five-step method before you look at the answers.
- Ground speed is 135 kt. How long does it take to fly 292.5 NM?
- A flight departs at 0615 IST and takes 2 hours 50 minutes. What is the ETA in UTC?
- Convert 450 litres of fuel to kilograms at a density of 0.72 kg per litre.
- True heading 270, variation 4 degrees East, deviation 3 degrees West. Find the compass heading.
- TAS 100 kt, track 180, wind 270 at 20 kt. Find the heading and ground speed.
- Track 090, wind 150 at 30 kt. Find the headwind and crosswind components.
- On a 1:1,000,000 chart you measure 6.5 cm. How many nautical miles is that?
- On a 150 NM leg, after 50 NM you are 5 NM right of track. What heading change brings you to the destination?
- Ground speed 105 kt, distance 252 NM, fuel flow 38 litres an hour. Find the time and trip fuel.
- Safe endurance is 3 hours 30 minutes. Ground speed out is 110 kt and home is 130 kt. Find the time and distance to PNR.
- Find the departure (east-west distance) for a change of longitude of 4 degrees at latitude 50 degrees North.
- An aircraft must descend 8,000 ft at 500 feet per minute with a ground speed of 120 kt. How long does the descent take, and how many nautical miles does it cover?
Answers and Explanations
| # | Answer | Quick explanation |
|---|---|---|
| 1 | 2 h 10 min | 292.5 ÷ 135 = 2.1667 h = 130 min |
| 2 | 0335 UTC | 0615 IST = 0045 UTC. Add 2:50 to get 0335 UTC |
| 3 | 324 kg | 450 × 0.72 |
| 4 | 269 | Magnetic = 270 − 4 = 266. West deviation makes compass greater: 266 + 3 = 269 |
| 5 | Heading about 192, GS about 98 kt | Wind from the right (west of a southbound track). WCA = arcsin 0.2 = 11.5 degrees, so heading = 180 + 11.5. GS = square root of (100² − 20²) |
| 6 | Headwind 15 kt, crosswind about 26 kt from the right | Wind angle is 60 degrees. 30 × cos 60 = 15 and 30 × sin 60 = 26 |
| 7 | About 35 NM | 6.5 × 10 km = 65 km, then 65 ÷ 1.852 |
| 8 | 9 degrees left | Track error = (5 ÷ 50) × 60 = 6. Closing angle = (5 ÷ 100) × 60 = 3. You are right of track, so turn left by 9 degrees |
| 9 | 2 h 24 min, 91.2 litres | 252 ÷ 105 = 2.4 h. 2.4 × 38 = 91.2 |
| 10 | About 1 h 54 min, about 209 NM | 3.5 × 130 ÷ 240 = 1.896 h. Distance = 1.896 × 110 = 208.5 NM |
| 11 | About 154 NM | 4 × 60 × cos 50 = 240 × 0.643 |
| 12 | 16 min, 32 NM | 8,000 ÷ 500 = 16 min. At 120 kt (2 NM a minute), 16 × 2 = 32 NM |
Score yourself, then update your error log. If you missed questions 4 or 5, revisit the direction rules in the wind and TVMDC sections above.
How The Pilot's Compass Teaches Air Navigation
Air Navigation becomes easier when an instructor can see your working. At The Pilot's Compass, Commander Naveen Pandita (Retd.) teaches Navigation with a practical, step-by-step approach, and our IAF Qualified Flying Instructors check your workings during live sessions.
- Live interactive online classes.
- Live plotting review of your chart work and calculations.
- Drills on the Dalton/CRP-5 and CX-3 flight computers.
- Doubt-solving sessions topic by topic.
- DGCA-style CBT mock tests with error review.
Cohorts are capped under 20 students, so every student gets personal feedback. Explore our DGCA CPL Ground Classes Program Page to join the next batch.
Frequently Asked Questions
Should I use a flight computer or a calculator? Learn the principles with exact formulas, and practise on the tool you are allowed to use in the exam. For step-by-step manual CRP-5/E6B instructions, see our CRP-5 and E6B section in the main DGCA Air Navigation guide.
How many practice questions should I solve in a week? Quality beats volume. Thirty carefully reviewed problems teach more than a hundred rushed ones.
Where can I get more practice sets? Use the practice sections of your recommended books (see our DGCA books guide), and timed mock exams as the exam date approaches. Live ground classes with instructor review of your workings can catch direction and method errors that self-checking may miss.
Continue Reading
- DGCA Air Navigation Guide
- DGCA Meteorology Guide
- DGCA Exam Preparation Guide
- DGCA Books 2026
- How to Clear DGCA Exams on First Attempt
Struggling with navigation calculations? In our live DGCA ground classes, instructors check your plotting and workings in real time. Book a free counselling session to find the right plan for your timeline.
Official Sources & References
- DGCA Pariksha Portal: https://pariksha.dgca.gov.in
- Directorate General of Civil Aviation (DGCA) Portal: https://www.dgca.gov.in
All practice questions and worked examples are original and for educational use. The official syllabus, exam instructions and permitted tools are set by DGCA and may change.
Frequently Asked Questions
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