Definition
A notification from ATC advising a pilot of a recommended speed for spacing, sequencing, or traffic flow purposes. The advisory is not a clearance or instruction to maintain that speed, and the pilot is expected to use it as guidance unless an actual speed assignment is issued.
Plain English
ATC tells the pilot what speed would help with traffic flow or spacing. It is a suggestion to help the controller manage traffic, not an order the pilot must follow.
Context Anchor
Seen or heard during ATC communications, especially when aircraft are being lined up with other traffic for arrival, departure, or en route spacing.
Derivation
“Speed” refers to how fast something moves. “Advisory” comes from “advise,” meaning to give guidance or counsel. Together, the term points to guidance about how fast to fly, rather than a speed that automatically overrides all other requirements.
Why Pilots Care
Following the advisory keeps proper separation from other traffic and prevents the need for sudden maneuvers.
Intuition Check
Do not read “advisory” as “mandatory clearance.” Do not read it as “optional and meaningless” either; it is useful guidance that should be followed when safe and consistent with other instructions.
Example Sentence 1
ATC issued a speed advisory of 280 knots to help sequence the flight behind slower traffic on the arrival.
Example Sentence 2
We received a speed advisory to slow to 140 knots while entering the downwind leg for traffic sequencing.