Definition
Defined bands or layers of airspace stacked vertically, each covering a specific range of altitudes. In en route operations, airspace is organized into these layers so that traffic, navigation services, and procedures can be managed at different altitude levels.
Plain English
Slices of airspace stacked on top of each other like floors in a building. Each floor covers a certain range of heights.
Context Anchor
Seen in instrument en route procedure discussions, especially when substitute airway procedures or route rules change with altitude.
Derivation
From Latin stratum, meaning 'a layer' or 'something spread out.' The plural is strata. The word is used in geology for layers of rock, and aviation borrows it for layers of airspace stacked by altitude.
Why Pilots Care
Correct use of altitude strata maintains traffic separation and compliance with published substitute routes.
Grounding Statement
Picture the airspace above the ground divided into horizontal layers, with each layer covering a different range of altitudes.
Intuition Check
Do not think of strata as rock layers or physical walls in the sky. In this context, altitude strata are defined altitude ranges used to organize procedures and requirements.
Example Sentence 1
The controller assigned a route that kept the flight within the lower altitude strata for the first segment.
Example Sentence 2
Eastbound aircraft are assigned the upper altitude stratum to ensure vertical separation from opposing traffic.