Lowest safe altitude
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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.
[edit] FAA Definition
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 § 191 of Part 91 of the Federal Aviation Regulations (FAR):
- Anywhere: an altitude allowing a safe emergency landing without undue hazard to person or property on the ground;
- Over Congested Areas: an altitude of 1,000 feet above the highest obstacle within a horizontal distance of less than 2,000 feet;
- Over Populated Areas: an altitude of 500 feet AGL;
- Over Open Water or Sparsely Populated Areas: an altitude allowing for a linear distance greater than 500 from any person, vessel, vehicle, or structure;
- Helicopters: an altitude lower than in definitions 2, 3, and 4 above, as long as it is not in violation of definition 1 and in compliance with any routes or altitudes specifically prescribed for helicopters by the Administrator.
