Instrument Landing System (ILS)

Context

Dense smog has disrupted flight operations across several Indian airports due to poor visibility, revealing deficiencies in pilot training for Category III Instrument Landing Systems (ILS).

Understanding ILS Categories

• Definition: ILS is a precision-based ground navigation system assisting pilots in landing during low-visibility conditions.
• Categories:
  • CAT I: Basic ILS approach with a minimum decision height (DH) of 200 feet and a runway visual range (RVR) of at least 550 meters.
  • CAT II: Enhanced precision with lower DH and RVR requirements.
  • CAT III: Advanced capabilities:
    • CAT IIIA: Allows landings with RVR as low as 200 meters.
    • CAT IIIB: Enables landings with RVR as low as 50 meters.
    • CAT IIIC: Facilitates landings in zero visibility, operational in some global airports like JFK, New York.

Components of the ILS

1. Localiser (LOC):
   • Provides horizontal (azimuth) guidance, ensuring alignment with the runway’s centerline.
   • Located at the far end of the runway.
2. Glideslope (GS):
   • Offers vertical guidance for the optimal descent path.
   • Positioned near the middle of the runway.

Advantages of ILS

• Enhanced Safety: Guides pilots in low-visibility scenarios, reducing the risk of accidents.
• Operational Continuity: Ensures minimal disruption in flight operations during adverse weather conditions.
• Precision: Delivers accurate horizontal and vertical guidance for seamless landings.

Current Scenario in India

• CAT IIIB-Equipped Airports: Delhi, Lucknow, Jaipur, Amritsar, Bengaluru, and Kolkata support CAT IIIB operations.
• Limitations: India lacks CAT IIIC infrastructure for zero-visibility landings, unlike some international airports.
• Training Gaps: Pilot training for advanced CAT III systems needs strengthening.

Way Forward

• Training Upgrades: Improve pilot training for CAT III systems to enhance operational preparedness.
• Infrastructure Development: Invest in upgrading airports to support CAT IIIC landings for seamless operations during extreme weather conditions.
• Public Awareness: Inform passengers about delays due to safety measures during low visibility to mitigate dissatisfaction.