Definition
An advisory term used by traffic management to describe a recommended weather-related routing or altitude envelope around significant convective or hazardous weather. It identifies the airspace volume considered acceptable for traffic flow while avoiding the affected area.
Plain English
A suggested 'safe corridor' around bad weather that controllers and traffic managers use to keep airplanes flowing without flying through the worst of it.
Context Anchor
Seen in route planning and airspace information related to military training routes.
Derivation
From 'meteorological' (relating to weather) and 'envelope' (a bounded area or volume). The term frames a weather-avoidance region as a defined space with edges, rather than a single line or route.
Why Pilots Care
Flying below this altitude may cause the controller to lose radar contact, requiring the pilot to revert to own navigation or request a higher altitude.
Intuition Check
MRE does not mean a meal in this aviation context. Here it means Military Route Extension, a published route-related segment for military flight operations.
Example Sentence 1
Center advised that an MRE was in effect around the line of thunderstorms over the Ohio Valley, so we accepted the offered deviation south.
Example Sentence 2
Pilots should not accept vectors below the published MRE without confirming radar coverage with ATC.