Definition
An emergency-use altitude depicted on instrument approach charts, providing at least 1,000 feet of obstacle clearance within a defined radius (typically 25 nautical miles) of a specified navigation facility or fix on the approach. MSA is intended for emergency use only and does not guarantee navigation signal reception or compliance with ATC clearances.
Plain English
A safe altitude shown on an approach chart that keeps you above all obstacles within a circle around a chosen point. It's there for emergencies, not for normal flying.
Context Anchor
Seen on instrument approach charts and used during inadvertent entry into cloud when a pilot needs a quick altitude that keeps the aircraft clear of terrain and towers.
Why Pilots Care
Provides a reliable altitude floor that prevents controlled flight into terrain when visual references are lost.
Grounding Statement
If you cannot see outside, the MSA gives you a published height to aim for so terrain and obstacles are not the first threat.
Intuition Check
Do not read “safe” as meaning safe in every way. MSA mainly means obstacle clearance in a defined area; it does not mean clear of weather, established on a route, or cleared by ATC.
Example Sentence 1
After entering unexpected cloud, the pilot climbed to the MSA shown on the approach chart while requesting help from ATC.
Example Sentence 2
Approach charts show the MSA so crews know the safe altitude to use in the terminal area during an emergency climb.