Definition
The lowest published altitude on a Federal airway, jet route, or other direct route segment that guarantees acceptable GNSS signal reception for navigation and provides the required obstacle clearance, when GNSS is the navigation source being used. It applies only to aircraft using GNSS-based navigation along that segment.
Plain English
The lowest altitude you can legally fly on a particular route segment when you are navigating by satellite, and still be sure of two things: a reliable satellite signal and safe clearance above terrain and obstacles.
Context Anchor
Seen on IFR en route charts and in route planning when a route segment has an altitude specifically tied to satellite-based navigation.
Derivation
GNSS refers to satellite navigation systems such as GPS. 'Minimum En Route IFR Altitude' is the established term for the lowest legal altitude on an instrument route. The 'GNSS' prefix simply specifies that this MEA applies when satellite navigation is the means of guidance, rather than ground-based navaids like VORs.
Why Pilots Care
It can allow a lower altitude than traditional ground-based MEAs on some routes, helping avoid icing layers or turbulence while preserving required safety margins.
Intuition Check
Do not read “minimum” as a recommended cruising altitude. Here it means the lowest published altitude that still provides the required protection for that satellite-navigation route segment.
Example Sentence 1
Because they were navigating by GPS, the crew checked the GNSS MEA on the chart before descending to their cruise altitude.
Example Sentence 2
With GNSS available, the flight could legally use the lower Global Navigation Satellite System Minimum En Route IFR Altitude rather than the standard MEA.