Icing, hail, and turbulence

The en route hazards that are not thunderstorms: structural ice, hail falling in clear air, mechanical and wind-shear turbulence, and the microburst.

14 min read · Weather

After this lesson you can

  • State the two conditions required for structural icing and identify the three types of ice by temperature range.
  • Explain what ice does to an airfoil, including the tailplane stall hazard.
  • Describe the mechanism of a microburst and its characteristic dimensions and wind change.
  • Explain why hail and turbulence can be encountered outside the visible boundary of a thunderstorm.

Not every en route hazard requires a thunderstorm. This lesson covers the ones that can catch a pilot in apparently ordinary IMC or even in seemingly clear air near a storm: structural icing that builds silently on the airframe, hail that falls miles from any visible cloud, and the sudden, violent wind changes of mechanical turbulence and the microburst.

The next lesson goes inside the thunderstorm itself; this one covers the hazards you need to respect whether or not you ever see a cumulonimbus cloud.

The rest of this lesson

  1. 1.Structural icing: the two conditions
  2. 2.Three types of ice
  3. 3.What ice does to the airfoil, and the tailplane stall
  4. 4.Hail
  5. 5.Turbulence you can anticipate
  6. 6.The microburst

These 6 sections, their figures, the checks along the way and the end-of-lesson quiz come with the PPL track. Paid once, yours for good.

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Key terms

Try to recall each definition before turning the card.