Which term describes the altitude used to ensure terrain clearance within a navigational sector?

Which term describes the altitude used to ensure terrain clearance within a navigational sector?

• A. Minimum Sector Altitude (MSA)
• B. Minimum Safe Altitude (MSA)
• C. Mean Sea Level (MSL)
• D. Absolute Altitude

Answer: (A)

Minimum Sector Altitude is the altitude that guarantees terrain and obstacle clearance within a defined navigational sector around a VOR or other navigation aid. It’s chosen so that, within that sector, there is a safe buffer above the highest obstacle—typically 1,000 ft of clearance (2,000 ft in mountainous areas). The altitude is usually expressed as height above mean sea level, and it helps pilots stay clear of terrain while navigating through that sector. Mean Sea Level is simply the reference level for altitudes, not a protective altitude, and Absolute Altitude refers to height above the ground, not the sector-specific clearance.

Minimum Sector Altitude is the altitude that guarantees terrain and obstacle clearance within a defined navigational sector around a VOR or other navigation aid. It’s chosen so that, within that sector, there is a safe buffer above the highest obstacle—typically 1,000 ft of clearance (2,000 ft in mountainous areas). The altitude is usually expressed as height above mean sea level, and it helps pilots stay clear of terrain while navigating through that sector. Mean Sea Level is simply the reference level for altitudes, not a protective altitude, and Absolute Altitude refers to height above the ground, not the sector-specific clearance.