📘 IAS Prelims 2025 — GS-I | Q.94 | Classroom Explanation
(Science & Technology | Space Applications | Navigation Systems)

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📌 Question

Q.94)
GPS-Aided Geo Augmented Navigation (GAGAN) uses a system of ground stations to provide necessary augmentation.
Which of the following statements is/are correct in respect of GAGAN?

I. It is designed to provide additional accuracy and integrity.
II. It will allow more uniform and high quality air traffic management.
III. It will provide benefits only in aviation but not in other modes of transportation.

Select the correct answer using the code given below:

(a) I, II and III
(b) II and III only
(c) I only
(d) I and II only

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✅ Correct Answer: (d) I and II only

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🧑‍🏫 Classroom Explanation

This is a classic UPSC S&T navigation systems question where:

• primary objective,
• sectoral impact, and
• over-restriction traps
  are carefully mixed.

Let us decode it cleanly.

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🛰️ What is GAGAN? (Core Concept)

• GAGAN = GPS-Aided Geo Augmented Navigation
• India’s Satellite Based Augmentation System (SBAS)
• Jointly implemented by:
  • ISRO
  • Airports Authority of India (AAI)

📌 Purpose
To enhance accuracy, integrity, continuity and availability of GPS signals over Indian airspace for safety-of-life applications, especially aviation.

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🔍 Statement-wise Analysis

🔹 Statement I
It is designed to provide additional accuracy and integrity. ✅

• Standard GPS accuracy ≈ 20 metres
• With GAGAN:
  • Accuracy improves to 1–2 metres
  • Integrity monitoring alerts pilots within seconds if signals degrade
• Critical for:
  • Precision approaches
  • Landing in poor visibility

✔️ Correct

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🔹 Statement II
It will allow more uniform and high quality air traffic management. ✅

• Enables:
  • Optimised flight paths
  • Reduced fuel burn
  • Better airspace utilisation
• Crucial for:
  • Congested air corridors
  • Seamless navigation across Indian FIR

✔️ Correct

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🔹 Statement III
It will provide benefits only in aviation but not in other modes of transportation. ❌

🚫 UPSC Trap Alert

Although aviation is the primary focus, GAGAN also supports:

• 🚆 Railways (train tracking)
• 🚢 Maritime navigation
• 🚗 Road transport & logistics
• 🌾 Precision agriculture
• 🌪️ Disaster management & search-and-rescue

❌ Hence, “only aviation” is incorrect

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🧠 Why Option (d) is Correct

✔️ Statements I and II are accurate
❌ Statement III is an over-restrictive trap

➡️ Correct combination: (d)

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🧠 One-Line Memory Hook (Prelims Gold)

“GAGAN sharpens GPS for skies first, but guides land and seas too.”

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📍 GS Mapping

Space Technology & Civil Applications

GS Paper I

Science & Technology

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