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Microbursts

  • sydpilot
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sydpilot created the topic: Microbursts

The CASA website Subject Feedback section lists microbursts as one area where students fall short.
"Microbursts, and their effects on performance (airspeed, shear, updrafts/downdrafts, flight performance indicators) particularly during take-off and landing operations."

Can you please let me know more about the effects of microbursts?
In particular, on an approach to land, would there be an increase/decrease in headwind/tailwind.
From what I understood, there is strong wind shear and the the flight path will get steeper. Corrrect me if I'm wrong.

I completed the CMET exam today with a score of 85% (self study). Was a bit disappointed with myself as I could have done a lot better. CNAV is the next exam.

Thank you Bob, Rich and Ray for your help. Great text books too; so easy to follow and comprehend.
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  • Neville75
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Neville75 replied the topic: Microbursts

If you can, view an episode of Air crash investigations (invisible killer - delta 191) is a great explanation of how an airliner became victim to a microburst.

Congrats on the exam, I did CMET yesterday and passed also. I've decided to do aero next.

nev
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  • sydpilot
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sydpilot replied the topic: Microbursts

Thanks. Yes, I do enjoy the show and will see if I can get a hold of that episode.
This was the first of the CPL exams so I do have a few more opportunities to do better.
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  • Ray
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Ray replied the topic: Microbursts

Microbursts are dangerous, have no illusions. They are most common in a dry lower layer with moist air above. This is most often evidenced by the phenomena known as virga (precipitation not reaching the ground). It is particularly common in lower levels under decaying thunderstorm cells.

The virga evaporates as it reaches the lower and dryer layer, and in doing so the parcel of air loses a great deal of heat (latent heat of evaporation). This creates a parcel of very dry cold air that is much more dense than the surrounding air and will sink rapidly due the higher density. If you fly through this air, you will also sink along with it (not good at low level!).

If the microburst is at very low level, as the descending air approaches the ground it will 'fan out' (it cannot descend below the ground), so if you encounter this effect on approach to land you will initially have an increased headwind as you approach the microburst, then a very strong sink rate (with no head or tailwind) and finally a tailwind as you exit the microburst. If you are on finals this is not a good combination.

Never ever ever fly below virga at low level, and never ever try to get past a thunderstorm by flying under it. It might work for you a few times but eventually you will end up a statistic of microbursts with 'pilot error' writ large on your gravesite. It is not unusual for microbursts to be in the vicinity of -10,000 feet per minute. Precious few aircraft ever built stand a chance against that.
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