Minimum Safe Altitude
What is minimum safe altitude?
Minimum Safe Altitude (MSA) is the minimum altitude published on instrument approach charts that guarantees at least 1,000 feet of obstacle clearance for emergency use within a specified distance (usually 25 nautical miles) of a listed navigation facility. It is meant for emergencies only, not as a routine approach altitude. Think of it as your "safety floor" if you lose your bearings on approach—a ring of guaranteed terrain clearance around the navaid.
Also known as: MSA, minimum safe altitude, minimum sector altitude
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