Originally Posted by
MarkerInbound
There are no CFR 14 regulations regarding block altitudes in the FAA system. If you flew outside of your cleared altitudes you could be subject to a violation like any clearance. The Instrument Pilot Handbook and the Air Traffic Control order simply say it is a block of altitudes assigned by ATC to allow altitude deviations. The IPH also suggests requesting a block if you are unable to maintain altitude due to turbulence.
Markerinbound ( and wilco77)
Not quite so, refer to a "Cruise" clearance, this is a block altitude clearance of a particularly flexible king, see the FAA AIM and the Pilot/Controller Glossary.
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