Minimum Safe Altitudes
91.119 states that no one can operate an airplane below an altitude such that:
- Anywhere: If a power unit fails, an emergency landing without undue hazard to persons or property on the surface.
- Over congested areas*: 1000' above the highest obstacle, within a 2000' radius of the aircraft
- Over noncongested areas: 500' above the surface, except over open water or
sparsely populated areas.
- In this case, cannot be more than 500' from any person, vessel vehicle, or structure
Under IFR
91.177 states that no person may operate and aircraft under IFR below:
- The minimum altitude for the route or segment (usually the MEA or MOCA), except for takeoff and landing
- If no minimum IFR altitude is defined, then:
- Over mountainous terrain: 2,000 feet above the highest obstacle within a horizontal distance of 4nm from the course flown
- Over nonmountainous terrain: 1,000 feet above the highest obstacle within a horizontal distance of 4nm from the course flown
* Can be denoted by yellow shading on a sectional.