The lowest safe altitude (LSALT) is a term used in aviation and in particular in air navigation. It is an altitude that is at least 1,000 feet above any obstacle or terrain within a defined safety buffer region around a particular route that a pilot might fly. The safety buffer allows for errors in the air by including an additional area that a pilot might stray into by flying off track. By flying at or above this altitude a pilot complies with terrain clearance requirements on that particular flight leg.
In the United States in particular, the Federal Aviation Administration calls this concept the Minimum Safe Altitude (MSA), and specifically defines it as follows in § 119 of Part 91 of the Federal Aviation Regulations (FAR):
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