Syllabus: Important Geophysical phenomena
Context
- Hayli Gubbi volcano in northern Ethiopia erupted on November 23, first time in 12,000 years.
- DGCA issued safety directives after volcanic ash drifted into Indian airspace on November 24–25.
How the Ash Travelled
- The eruption sent thick ash plumes up to 14 km high.
- Ash drifted across the Red Sea towards Yemen, Oman, and Iran.
- Entered India’s western border at 5:50 pm on Nov 24, exited by 10:30 pm on Nov 25.
- Moved at 100–120 km/hr at 15,000–25,000 feet altitude.
- Passed over Rajasthan, Gujarat, Delhi-NCR, Punjab, Uttar Pradesh before moving towards China.
- Plume contained volcanic ash, sulphur dioxide, glass and rock particles.
Why Volcanic Ash Is Dangerous for Aircraft
- Jet engines operate at ~1,600°C with air flowing at 600 mph.
- Volcanic ash contains silicates that melt inside engines and re-solidify into glassy deposits.
- Deposits block tiny cooling holes, disrupting airflow.
- Causes engine overheating, power loss, or complete shutdown.
- Volcanic ash also reduces visibility and contaminates runways.
DGCA Directives
- Airlines told to avoid affected altitudes/regions.
- Mandatory reporting of any engine-performance issues, cabin smoke, or unusual odour.
- Airports ordered to inspect runways for volcanic ash contamination.
- Runway operations to be restricted or suspended if required.
Impact on Flights
- Air India cancelled nine flights (Nov 24–25) from Dubai, Doha, Dammam; conducted precautionary aircraft checks.
- Akasa Air cancelled services to/from Jeddah, Kuwait, Abu Dhabi.
Historical Incidents Highlighting the Risk
- British Airways Flight (1982)
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- Flew into ash near Mount Galunggung, Indonesia.
- All four engines failed; cabin oxygen levels dropped.
- Engines restarted after descending 25,000 ft, enabling safe landing despite clouded windscreens.
- KLM Flight (1989)
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- Encountered ash from Mount Redoubt, Alaska.
- All engines shut down at 24,000 ft; multiple restart attempts.
- Landed safely, but engines worth $80 million were destroyed.
Conclusion
- Volcanic ash is a critical aviation hazard due to severe engine damage risks.
- The DGCA’s early advisory helped minimise operational disruptions and ensured flight safety.