BY LOKESH PATIL Mechanical Engineering1

About Microbursts Their effect on aviation

Safety measures to reduce accidentsConclusion

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Localized column of sinking air causing damaging divergent and straight line winds Its width can stretch upto 4 kms and can last upto 15 mins

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Microbursts can be classifiedinto two types:

Microburst

Wet Microburst

Dry Microburst

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Dry microburst is a result of evaporation of rain due to dry air present below the clouds The only visual sign of this may be the dirt picked up by the wind near land surface

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These are characterized by significant precipitation near the surface These rely more on the drag of precipitation for downward acceleration

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Contact Stage In this stage the downdraft begins its decent towards ground from cloud base.During this stage,wind speed is highest

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Outburst During the outburst stage, the wind "curls" as the cold air of the downburst moves away from the point of impact with the ground.

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Cushion Stage During the cushion stage, winds about the curl continue to accelerate, while the winds at the surface slow due to friction

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The scale and suddenness of a microburst makes it a great danger to aircraft, particularly those at low altitude which are taking off and landing There have been around seven known accidents caused only due to microbursts claiming 650 lives

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Aircraft takes off on desired path as it gets the required lift force

Due to heavy tailwind the net lift force decreses and gets off the desired path

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At 6000 ft,due to the strong headwinds plane takes off at a very steep angle At 9000 ft plane pitches downwards dangerously due to strong tailwinds and loses control At 4km mark,plane crashes.

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1)Normal landing course 2)Aircraft encounters increasing downdraft and tailwinds 3)Airspeed decreases with reduction in visibility 4)Airplane crashes short off approach

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1976 LLWAS-Low Level Windshear Alert System Consists of a centerfield wind sensor and five other placed along the periphery of airfield

1980 TDWR-Terminal Doppler Weather Radar Detection accuracy increased to 95% from 25%

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1990 WSP-Weather systems processor It was a add-on for Airport surveillence radar and provided windshear warnings Late 1990 ITWS-Integrated Terminal Weather system Combined all previous systems into one integrated system. Has the capability for accident investigations

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