Lowest Safe Altitude - FAA Definition

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 § 119 of Part 91 of the Federal Aviation Regulations (FAR):

1. Anywhere: an altitude allowing a safe emergency landing without undue hazard to person or property on the ground;
2. Over Congested Areas: an altitude of 1,000 feet above the highest obstacle within a horizontal distance of less than 2,000 feet;
3. Over Populated Areas: an altitude of 500 feet AGL;
4. Over Open Water or Sparsely Populated Areas: an altitude allowing for a linear distance greater than 500 from any person, vessel, vehicle, or structure;
5. Helicopters: If without hazard to persons or property on the surface, an altitude lower than in definitions 2, 3, and 4 above, provided in compliance with any routes or altitudes specifically prescribed for helicopters by the FAA.