Definition
The lowest altitude at which an aircraft may legally and safely be operated under the applicable Federal Aviation Regulations, providing adequate clearance from terrain, obstacles, and populated areas. In a controller context, it also refers to the lowest altitude an air traffic controller is authorized to assign to an aircraft, which provides the required obstacle clearance within a specified area.
Plain English
The lowest you are allowed to fly while still keeping a safe distance from the ground, buildings, people, and obstacles.
Context Anchor
Seen in flight planning, emergency planning, chart reading, and notices where pilots must know how low they can safely fly in a specific area.
Why Pilots Care
Prevents controlled flight into terrain by guaranteeing standardized obstacle clearance during IFR operations.
Grounding Statement
If the ground, towers, or buildings are close below you, the minimum safe altitude is the bottom line you do not plan to go below.
Intuition Check
Do not read minimum safe altitude as “an altitude that is always safe.” It means the lowest altitude considered safe only for the stated area, procedure, or situation, with the required clearance built in.
Example Sentence 1
Over the city, the pilot maintained at least 1,000 feet above the highest obstacle to comply with the minimum safe altitude rule.
Example Sentence 2
She checked the chart sector and confirmed the minimum safe altitude was 4,800 feet before descending.