CFI Topics

But, There is More

Lesson 2

But, there is a problem with that. Look at the bottom portion – the negative g part – of the Vg diagram. There is a similar point there where the negative limit load (which is far less “load” or G’s than the positive) intersects the stall line – effectively a “negative Va”. In virtually ALL cases, this is a significantly lower speed than the Va on the positive g side, and in addition is much lower in G-force.

So, here’s the question. Have you ever had ONLY positive, or “upward”, turbulence (i.e. nothing to the negative or downward side)? I know that I surely haven’t. What does this mean? Since no negative Va speeds are published – anywhere – when faced with turbulence you MUST slow to a speed SLOWER than Va to truly be protected! How much slower? Since nothing is specified here, get as much slower as you can and still have decent aircraft control – and fly out of the turbulence as soon as practical.

(For further illustration, detail, and discussion of this issue, see the companion PowerPoint Presentation – “Vg Diagram and Va – Good Friends of the Pilot” in the SAFE Library by the same author)

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