Definition
An altitude reservation is a block of airspace, defined by altitude, time, and route or geographic boundaries, that ATC sets aside for a specific operation that cannot easily fit standard traffic flow. ALTRVs are coordinated by the FAA's Air Traffic Control System Command Center and are commonly used for activities such as air refueling, large formation flights, missile launches, military exercises, and certain special missions. They may be stationary (fixed area) or moving (travelling along a route with the operation).
Plain English
A chunk of sky that ATC reserves for a particular flight or operation during a set time window, so other traffic stays clear of it.
Context Anchor
Seen in flight planning, military or special-use operations, and air traffic coordination involving groups of aircraft or unusual altitude needs.
Derivation
From 'altitude' (the vertical layer of airspace involved) and 'reservation' (something held aside for a specific user). The name reflects exactly what it is: airspace held aside, defined by its altitudes.
Why Pilots Care
Pilots must check for active ALTRVs during preflight planning to avoid entering restricted airspace or receiving unexpected reroutes.
Intuition Check
Do not read “reservation” as a casual request or preference. In this context, it means airspace and altitudes have been formally set aside under specific conditions.
Example Sentence 1
Center advised us to expect a reroute because a moving ALTRV for air refueling was active along our planned track.
Example Sentence 2
ATC advised the flight to remain clear of the active ALTRV until the military exercise ended.