Definition
The lowest published altitude on a defined airway segment that provides acceptable navigation signal coverage when using a GNSS-based navigation system, while also meeting required obstacle clearance. It applies only to aircraft navigating by GNSS and may be lower than the conventional MEA for the same segment because GNSS does not depend on ground-based VOR or NDB reception.
Plain English
It is the lowest altitude you are allowed to fly along an airway when you are using satellite navigation. At this altitude you are guaranteed to clear terrain and obstacles, and your satellite-based system will work properly along that route.
Context Anchor
Seen on instrument route charts and in route planning when a segment has a minimum altitude tied to satellite navigation use.
Derivation
MEA stands for Minimum En Route Altitude, a long-standing IFR airway altitude. The 'GNSS' prefix was added when satellite navigation became approved for en route flight, allowing a separate, often lower, minimum that does not rely on ground-based navigation aids.
Why Pilots Care
It permits lower altitudes on approved GNSS routes than some conventional MEAs while preserving obstacle clearance and signal integrity.
Intuition Check
Do not read GNSS MEA as just a general suggested cruising altitude. It is a published minimum altitude for a specific route segment when using approved satellite navigation.
Example Sentence 1
Cleared direct on the airway, the crew descended to the GNSS MEA shown on the chart since they were navigating by GPS.
Example Sentence 2
Flight planning tools display the GNSS MEA to confirm the route remains above all obstacles.