Plain English Meaning
A navigation chart pilots use when flying on instruments at high altitudes. It shows the routes, navaids, and ATC boundaries needed to fly safely in that part of the sky.
Full Definition
An aeronautical chart designed for instrument flight at and above 18,000 feet MSL, depicting the jet route structure, high-altitude airways, navigation aids, intersections, reporting points, and air traffic control boundaries used in that airspace.
Context Anchor
Seen during planning and in when a will be flown at or above 18,000 feet.