Why in News?

Following the April 22 Pahalgam terror attack, India suspended the Indus Waters Treaty as part of its measures against Pakistan.

In retaliation, Pakistan issued a NOTAM (notice to airmen) closing its airspace to Indian aircraft from April 24 to May 23, affecting several northern, southern, and Arabian Sea routes. India responded with a similar airspace restriction starting April 30, also lasting till May 23.

What’s in Today’s Article?

• NOTAM (notice to airmen)
• Timeline of India-Pakistan Airspace Closures
• Estimated Losses from Airspace Closures
• Airspace Changes in 2025: Key Developments and Impacts
• Role of International Aviation Law Depends on Political Will

NOTAM (notice to airmen)

• NOTAM is an official alert issued to pilots and airlines about temporary changes or hazards in flight operations—such as airspace closures, route changes, or construction—that may affect flight safety or planning.
• NOTAMs are issued by the civil aviation authority of a country. In India, it is issued by the Airports Authority of India (AAI).
• These notices are then distributed through international aviation networks to inform pilots and airlines globally.

Timeline of India-Pakistan Airspace Closures

• 1950s: India opposed Pakistan’s prohibited zone near the border as discriminatory. Resolved diplomatically, setting the precedent that such restrictions need valid security reasons.
• 1965 War: Post-war, both sides resumed overflights from March 1, 1966. Pakistan sought a direct route to Dhaka, having faced detours via Ceylon.
• 1971 Hijacking: After an Indian Airlines flight was hijacked to Lahore and destroyed, India banned civil and military overflights. The issue led to legal battles at ICAO and the World Court, and was resolved in 1976.
• Later Incidents: Airspace closures recurred during major conflicts—Kargil (1999), Parliament attack (2001), and Balakot strikes (2019)—highlighting airspace as a strategic tool.

Estimated Losses from Airspace Closures

• 2002: Post-Parliament Attack Losses
  • India’s Civil Aviation Ministry estimated annual losses due to airspace closure as follows:
    • Air India: ₹40 crore
    • Indian Airlines: ₹3.4 crore
    • Airports Authority of India: ₹5 crore (from landing, parking, and overflight charges)
  • Pakistan’s losses were estimated to be five times higher, according to India’s Civil Aviation Minister.
• 2019: After Balakot Strikes
  • Indian carriers suffered a collective loss of ₹548.93 crore (as per a Rajya Sabha reply).
  • Pakistan incurred a loss of around $50 million.
  • According to IATA, at least 220 international flights used Pakistan’s airspace for Asia-Europe connectivity before the ban.
• 2025: Projected Impact
  • Estimated consolidated loss for the Indian aviation sector (including cargo): ₹7,000 crore (indicative).
  • Based on 2019 data, Pakistan lost approximately: $2,32,000 per day in overflight charges; $3,00,000 per day including landing, parking, and navigation fees.

Airspace Changes in 2025: Key Developments and Impacts

• Temporary Closures and Route Restrictions
  • 32 airports in northern and western India were temporarily closed.
  • 25 Air Traffic Service (ATS) route segments within the Delhi and Mumbai Flight Information Regions (FIRs) were made unavailable from ground level to unlimited altitude for safety reasons.
    • ATS route segments are like invisible highways in the sky that aircraft follow for safe and efficient travel.
    • FIRs are large blocks of airspace managed by a country's air traffic control—Delhi FIR and Mumbai FIR are two of India's busiest.
    • When these 25 segments were marked “unavailable from ground level to unlimited altitude,” it meant:
      • No aircraft (civilian or military) could use those air routes.
      • This restriction applied to all altitudes, not just low-flying or high-flying aircraft.
  • Air traffic was rerouted and managed by ATC units in Mumbai, Ahmedabad, Nagpur, Kolkata, and Chennai.
• Waypoint Congestion and Rerouting
• India and Pakistan normally use about 12 shared points in the sky (called waypoints) to manage air traffic between their airspaces.
• But due to restrictions, flights had to be rerouted through only six waypoints, which are shared between India (Mumbai region) and Muscat (Oman’s airspace).
• To handle the extra traffic safely, air traffic controllers used standard rules to keep planes properly spaced apart—above, beside, and when crossing paths—to avoid any risk of collision.
• Limited Alternatives and Operational Challenges
  • Rerouting via China was not viable due to the rigid structure of Chinese airspace and mountainous terrain, which pose operational and safety challenges.
  • Suboptimal routes increased flight time and operational costs.

Role of International Aviation Law Depends on Political Will

• Although international aviation law offers channels for resolving disputes, their success relies heavily on the political will of the countries involved and a clear grasp of the specific details of the India-Pakistan standoff.