Ceiling and Visibility

These early pilots depended on a network of rotating beacon towers at four-mile intervals, like lighthouses in the sky. These facilities, operated by the federal government, used lamps powered by cylinders of acetylene. Simply by following the route from beacon to beacon, a pilot could arrive safely at the destination. Weather could be avoided because the planes flew at low altitudes, and illuminated diversion airfields were placed at frequent intervals. If the pilot felt things were deteriorating, he could be on the ground in less than 10 minutes.

Tim Vasquez

Tuesday, February 19, 2019 at 12:00 AM ET

Verified

** A Swiftair MD-83 of the same model that crashed
on Thursday. (Photo: Aero Icarus via Creative Commons)**

Key Takeaways:

Instrument flight emerged from early aviation needs, leading to standardized definitions of ceiling (lowest cloud layer covering over half the sky, AGL) and visibility (maximum distance identifiable objects can be seen).
Pilots must be aware of dangers like "whiteout," which demands reliance on instruments, and understand the capabilities and limitations of evolving measurement technologies, including modern automated systems.
Accurate forecasting of ceiling and visibility changes requires a comprehensive meteorological understanding, integrating current conditions, underlying weather patterns (like air mass characteristics), and local effects.

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This article is being prepared in the middle of the winter, and there’s probably no better time to talk about ceiling and visibility. These are the main parameters that determine whether or not we’re flying in instrument conditions, and if we’re unprepared, low ceilings and visibility can get us into serious trouble.

Ceilings in History

It was a simpler time when the Red Baron appeared in the French skies during World War I. Pilots stuck to clear air and avoided clouds where possible. Instrument flying got its start in the 1920s. The revolutionary U.S. Air Mail service grabbed national headlines and promised to be one of the biggest advances since the Pony Express.