Definition
An altitude inappropriate for the direction of flight and/or not in accordance with the cruising altitude rules of 14 CFR Section 91.159 or 91.179. ATC may assign such an altitude when traffic, terrain, or operational conditions make it preferable to the standard hemispheric rule altitude.
Plain English
An altitude that doesn't follow the usual rule of 'odd thousands eastbound, even thousands westbound.' ATC has assigned it for a specific reason, even though it doesn't match the direction of flight.
Context Anchor
Seen in air traffic control and FAA glossary language when discussing altitude assignments, direction-of-flight rules, and vertical spacing between aircraft.
Derivation
Random' comes from the Old French 'randon,' meaning 'rush' or 'without a set course.' In ATC use, it doesn't mean 'chosen by chance' — it means 'not following the standard direction-of-flight rule.'
Why Pilots Care
Ensures traffic separation while allowing flexible routing; pilots must verify the assigned altitude matches the clearance and is suitable for terrain and performance.
Intuition Check
Random does not mean careless or unsafe here. It means the altitude is outside the usual pattern or standard rule for that direction of flight.
Example Sentence 1
Center cleared us to maintain 8,000 feet eastbound — a random altitude — to keep us below opposite-direction traffic.
Example Sentence 2
Because we requested a direct routing, we received a random altitude instead of a published airway altitude.