Definition
A portion of an instrument approach procedure for which obstacle clearance and navigational accuracy have been evaluated and guaranteed, provided the aircraft remains within the defined lateral and vertical limits of that segment.
Plain English
A specific stretch of an instrument approach where, if you stay inside the defined boundaries, you are guaranteed to be safely clear of terrain and obstacles.
Context Anchor
Seen in instrument procedure design, instrument approach discussions, departure procedures, and obstacle-clearance planning.
Derivation
From Latin protegere, meaning 'to cover in front.' The segment is 'protected' in the sense that it has been surveyed and cleared in advance — obstacles within it have been accounted for, so the pilot flying inside it is shielded from collision risk.
Why Pilots Care
It tells the pilot exactly where obstacle protection is assured, allowing safe descent or climb decisions without visual reference.
Intuition Check
Protected does not mean the area is physically blocked off or free of all danger. It means the procedure design provides obstacle clearance if you stay within the required path and altitude limits.
Example Sentence 1
As long as the pilot remained within the protected segment of the approach, required obstacle clearance was assured.
Example Sentence 2
The crew verified they were inside the protected segment before turning inbound on the approach.