Here's the Lowdown on 'Vertical Visibility'

During any flight, a pilot will encounter several different flavors of visibility.

Scott Dennstaedt, Ph.D

Monday, February 26, 2024 at 12:59 PM ET

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FLYING contributor Scott Dennstaedt poses the question: Is vertical visibility even a legitimate visibility? [iStock]

Key Takeaways:

Vertical Visibility (VV) is not a true measure of visibility but represents the vertical distance one can see from the surface into an "indefinite ceiling," implying the sky is completely obscured by an atmospheric phenomenon.
VV occurs when automated systems like ASOS cannot detect a well-defined cloud base, primarily due to widespread moisture such as fog, mist, or precipitation scattering the laser ceilometer's signal.
Indefinite ceilings are always paired with low surface visibility and low IFR conditions, leading to longer transition times during flight, restricted flight visibility during instrument approaches, and increased difficulty for circle-to-land maneuvers.

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During any flight, a pilot will encounter several different flavors of visibility. This includes flight visibility, ground visibility, prevailing visibility, tower visibility, runway visual range, and vertical visibility.

But wait, is vertical visibility even a legitimate visibility? Actually, it’s a bit of a misnomer and not a true measure of visibility in the traditional sense. Vertical visibility is a close cousin to ceiling. That is, it represents the distance in feet a person can see vertically from the surface of the Earth into an obscuring phenomenon, or what is called an indefinite ceiling. What isn’t obvious is how vertical visibility is determined, and how this is different from a definite ceiling.