Definition
A published altitude that represents the highest usable altitude on a federal airway, jet route, RNAV low or high route, or other direct route segment. Flying above the MAA is not authorized because navigation signal reception or frequency protection cannot be guaranteed above that altitude.
Plain English
The highest altitude you are allowed to fly on that route. Go any higher and the navigation signals can no longer be relied upon, so it is off-limits.
Context Anchor
Seen on instrument charts and in discussions of charted IFR altitudes for airways, routes, and route segments.
Derivation
Maximum comes from the Latin maximus, meaning “greatest.” Authorized means officially allowed. Together, the words point to the greatest altitude officially allowed for that published route segment.
Why Pilots Care
Ensures reliable navigation signals remain usable and terrain or obstacles stay safely below the aircraft on IFR routes.
Intuition Check
Do not read “authorized” as “you are cleared to climb there.” MAA means the chart permits the route to be used no higher than that altitude; your clearance and other altitude limits still matter.
Example Sentence 1
The MAA on that airway segment is 15,000 feet, so we filed for 13,000 to stay within the protected altitude band.
Example Sentence 2
ATC cleared the aircraft only to the MAA because any higher would lose navigation coverage on that route segment.