Why in News?

A Singapore Airlines flight, from London’s Heathrow Airport to Singapore encountered severe turbulence while over the Andaman Sea/Bay of Bengal near the Irrawaddy Basin, Myanmar.

A passenger passed away and several others suffered injuries of varying degrees.

What’s in Today’s Article?

• What is Turbulence?
• When is Turbulence Dangerous for Aircraft?
• Have Instances of Turbulence Risen and is Climate Change Responsible?
• What can be Done to Avoid Dangerous Turbulence?

What is Turbulence?

• Turbulence is essentially unstable air that moves in a non-predictable fashion. Most people associate it with heavy storms.
• However, the most dangerous type - clear-air turbulence, happens most often in or near the high-altitude rivers of air called jet streams.
  • The main cause of such turbulence is wind shear, which occurs when two huge air masses close to each other move at different speeds.
  • If the difference in speed is big enough, the atmosphere can’t handle the strain, and it breaks into turbulent patterns like eddies in water.

When is Turbulence Dangerous for Aircraft?

• Aircraft undergo some form of turbulence on a regular basis and pilots are trained to deal with these.
• However, there have been several instances when intense turbulence has brought down modern jetliners.
• Therefore, on the basis of their nature and intensity, turbulence becomes dangerous for aircraft.
• For example,
  • A SpiceJet-operated Boeing 737-800 aircraft with 189 passengers encountered severe turbulence in 2022.
  • While descending, turbulence was created due to bad weather.
  • The airspeed suddenly dropped by around 100 knots, before rising again.
  • This led the crew and passengers to rise up (similar to a zero-gravity situation) and fall back down.
  • Two passengers were treated for severe head and spine injuries.
• While intense turbulence has been the main cause of an accident, several other factors have contributed to the accident, such as
  • Lack of proper training,
  • Poor dissemination of weather or wind related information, etc.

Have Instances of Turbulence Risen and is Climate Change Responsible?

• According to a study, clear-air turbulence rose by 55% over the North Atlantic between 1979 and 2020.
• Global warming as a result of greenhouse gas emissions (GHGs) could lead to higher wind speeds in the fastest upper-level jet stream.
  • The speeds will increase by 2% for every degree Celsius the earth warms.
• The global temperature has increased by at least 1.1 degrees Celsius since the pre-industrial era and it is expected to increase by 4 degrees Celsius by the end of the century if GHGs continue to rise at the same level.

What can be Done to Avoid Dangerous Turbulence?

• Passengers should
  • Listen to instructions from flight attendants;
  • Pay attention to the safety briefing at the beginning of the flight;
  • Wear a seat belt at all times;
  • Use an approved child safety seat or device if a child is under two; etc.
• Airlines should
  • Improve dispatch procedures by keeping communication channels open full-time;
  • Issue Flight Planning Guidance Charts (FPGs) and Significant Meteorological Information (SIGMETs);
  • Include turbulence in weather briefings;
  • Promote real-time information sharing between pilot and dispatcher;
  • Reinforce the carrier’s turbulence avoidance policy through dispatcher training;
  • Consider rerouting using atmospheric modelling and all applicable weather data;
  • Using operating procedures and training to prevent turbulence injuries, etc.