Safety
After Years of Accidents, 'Clear of Clouds' Remains Murky
The "clear of clouds" directive lays responsibility on the pilots, but with the lack of clarity, no pilot officially has a cloud incursion...until a crash.

One of the more subjective directives in the federal aviation regulations (FAR) is found in 91.155 where VFR pilots are instructed, in certain airspace, to maintain “clear of clouds.” The definition of “clear of clouds” is both straightforward and ambiguous.

While it logically means that pilots should refrain from entering clouds, the presence of scattered, or even lightly broken, cloud layers allow opportunity for pilots to skirt immersion in a clouded environment. (This might explain why online searches for the phrase will also bring up discussions of scud-running.)