What are downdraft wind shears??

There are many types of winds, but today we will talk about some very dangerous ones that affect aviation daily.ón. ¿Whaté are the descending winds wind shear or shear? Photo de flugsnug vía YouTube.

Given the recent non-fatal Aerom accidentéxico in Durango, where an embraer 190 are jokingó off the track and finishedó some 300 meters from the head, many speculations about whaté could have happened has been making rounds on the internet.

with this post, we do not want to draw conclusions and much less anticipate the results or causes of the accident, that only the final report and the country authoritiesís can give, but before the appearanceón in means over téterms wind shear, We find it prudent to inform the community about its meaning and what it implies for aviation.ón.

post writer by: Capturesán Rodolfo Estrella
FAA Commercial Pilot
Twitter: @rodo_estrella

And tésimple terms, shear is a conditionón where the wind within a short distance abruptly changes speed and directionón, be it horizontal or vertical, Shear is generally associated with a variety of meteorological conditions.ólogics like temperature inversions, frontal systems, strong surface winds and the más violent: the stormséelectricity and intense rain.

Of the kinds of shear in questionón severity studies show that wind speed changes range from 15 knots and currents with speeds greater than 500 feet per minute.

Figure 1 (FAA source)

The productionón of shear in the case of the storm theécitrica (figure 1) occurs during the dissipation stageón of it characterized by heavy rains that create downdrafts of air,  is áAreas usually have dimensions between 1 a 5 miles of diámetro.

La micro rádo

Within what is the shear or windshear, we found the fenóminus the micro rádo, which is one of the meteorological elementsólogics that affect the operationón berriesáutica  so más significant, these are powerful concentrated downdrafts of air, usually cover ásmall areasñace around 3.000 pieces of theámetro.

Its impact against the ground generates v ringsólateral axes of áareas up to 12.000 pieces of theámeter and can go up to 2.000 feet on the ground. These vórtices can generate eddy updrafts that can cause lateral stability problems in aircraft.

Ámicro r areasádo múMultiples may be present within the same phenomenonóless meteorolóassociated logic and its dissipation periodón is usually around 10 a 20 minutes laterés of its contact with earth.

Figure 2 (fuente: FAA)

Problems in operationón berriesáutica

The micro ráphages are particularly dangerous in the takeoff and landing phases because their effect más adverse comes from contact with the surface.

Shear and its effects are difíeasy to predict and are not fáeasily observable with the naked eye, which is why it is usually difficultíeasy to avoid it, however they have developed técones for handling in case of encountering them for the pilots and detection systemsón early flight in aircraft with advanced systems.

further, some airódromos have windshear reporting systems to warn flights about the phenomenonóless, However, The system is not implemented in all airlinesódromos and often the windshear reports come from aircraft that encounter the fenóexcept in flight.

Pilots are trained and evaluated regularly in the management of wind wind and this training consists of the recognition of wind wind based on the performance and behavior of the aircraft.ón upon encountering this fenóless. Thus, recovery procedures applyón of the control of aircraft that are affected by wind wind,

Regrettably, la variationón and  intensity and the conditions in which they can occur make any detection procedureón and/or handling are not completely effective so it will always beá a latent danger in any operationón aérea.

Figure 3 (fuente: FAA)

Regulatory agencies of the aero systemáutico around the world simply recommend not operating in airódromos where shear is reported (although its existence cannot always be known) and the industry directs its efforts in technologyífor detectionón effective shear both on land, as in instrumentationón inside aircraft.

Finally, the aerosolsíAircrews and pilot training programs focus on training crews to recognize and engage in the most effective manner.áis this fen effectiveóless.

Accidents toéconvicts by wind shear

In the history of aviationón, 113 accidents have been attributed to meteorological problemsólogic, among them, various due to wind shear or other extreme wind conditions.

This is a part of those accidents, being one of the más representative, that of Delta Air Lines in 1985 (ASN Source):