Definition
Published or ATC-issued limits on an aircraft's indicated airspeed during a specific phase of flight or segment of a procedure. On a Standard Instrument Departure (SID), speed restrictions appear as charted values (for example, 'Maintain 250 KIAS') that must be complied with unless ATC explicitly cancels them or the pilot requests and receives a different speed.
Plain English
Rules that tell you how fast you may or must fly at a certain point. On a departure chart, they appear as numbers next to a fix or altitude, and you have to fly at that speed until ATC tells you otherwise.
Context Anchor
Seen during departure planning for a SID, on instrument procedure charts, and in ATC instructions during climbs, descents, arrivals, and approaches.
Why Pilots Care
Ensures traffic separation, meets noise or performance requirements, and keeps the aircraft within safe operating speeds during climbs and descents.
Intuition Check
Do not read speed restrictions as suggestions or “normal speeds.” In this context, they are required speed limits for a specific part of the flight unless ATC changes them or the pilot reports they cannot comply.
Example Sentence 1
The SID included a speed restriction of 230 knots until passing 10,000 feet, so the crew left the autothrottle set accordingly during the climb.
Example Sentence 2
ATC issued a speed restriction requiring 180 knots until the next waypoint.