FLIGHT TURBULENCE (Syllabus: GS Paper 3 – S&T)

Context: A Singapore Airlines flight (SQ321) from London to Singapore recently encountered severe turbulence, resulting in one death and several injuries. 

Turbulence

• About: It means a pockets of disturbed air can have many causes, most obviously the unstable weather patterns that trigger storms
• Flight turbulence: It means disruption of airflow over the wings of an airplane, which causes it to enter irregular vertical motion.
• Types of flight turbulence: There are at least seven kinds of turbulence that an aircraft can run into:

oWIND SHEAR: Happens when there is a sudden change in wind direction, whether vertically or horizontally. Typically occurs close to thunderstorms, jet streams, etc.; tricky for pilots as tailwinds suddenly change to headwinds or vice versa.

oFRONTAL: Created in the frontal zone when warm air is lifted by sloping frontal surface and friction between opposing air masses. Most palpable when warm air is moist; intensity increases with thunderstorms. Most common close to thunderstorms.

oCONVECTIVE: When land surface temperature rises, the air above the ground heats up and rises, creating air pockets around it. Convection currents cause difficulties during approach as they tend to affect the rate of descent.

oWAKE: Forms behind an aircraft when it flies through air-creating wingtip vortices. Can be dangerous for small aircraft following bigger ones, which tend to disrupt the airflow more strongly in their wake.

oMECHANICAL: This type of turbulence occurs when tall solid objects such as mountains or highrise constructions disrupt the normal airflow, causing the air for planes to fly through to become dirty.

oCLEAR AIR: Occurs when an aircraft crosses from one air mass to another, which has a different direction. Clear air turbulence could also happen when an aircraft moves out of a jet stream. Clear air turbulence is mainly caused by wind or jet streams.

oMOUNTAIN WAVE: One of the most severe; these are oscillations that form on the downwind side of mountains when strong winds flow towards mountains in a perpendicular fashion. Aircraft tracking perpendicularly across, or downwind of a mountain, may experience sudden loss of altitude followed by a sudden reduction in airspeed.