# What is really meant by max 240 kt, 220 kt and 185 kt in the picture of Jeppesen chart?

What is really meant by max 240 kt, 220 kt and 185 kt in the picture of Jeppesen chart? What I don't understand is: are the speed limits for waypoints or for routes between waypoints. If speed restrictions mean routes between waypoints, do they cover before or after the waypoint? I will leave two examples below, one is STAR and one is SID chart.

For example at the STAR chart, is it possible to increase our speed above 240kt after CRL VOR and then reduce our speed to 220kt again at BU214 waypoint after crossing BU211 BU212 BU213 waypoints respectively?

Another example is from the SID chart: Does the speed limit for point BU710 cover the route to BU710 after takeoff? Or just the BU710 point? Or BU710 point and beyond?

The speeds are charted at waypoints and they apply when you cross that waypoint. On a departure, the restriction applies until crossing the waypoint but no longer applies afterwards - though another restriction at a later waypoint would apply. On an arrival, the reverse is true: fly whatever speed until the first restriction, then comply with that at & after the point.

The typical phrasing on US departure procedures is "do not exceed XXX knots until past YYYYY waypoint" - which rules out speeding up & then slowing down just for the waypoint. The reason behind this is that ATC wants to control the flow & separation of aircraft, and points provide "gates" to do that: everybody holds (no more than) 220 knots until "here", then (no more than) 240 knots until "here", and then normal climb speed after that.

The same logic applies on arrivals, with the defined points as places where the flow of traffic slows down in a uniform, predictable manner.

The general practice (which may or may not be codified in a given AIP or SOP) is that you want to get fast as soon as allowed (i.e. on departures), and stay as fast as possible for as long as allowed (on arrivals). So, on the top chart, you'd expect to slow to 240 so as to cross CRL at that speed, but no earlier. Then start slowing about 2 miles prior to BU214 so as cross it at 220, having held 240 until then. Sometimes it's necessary to slow sooner than this & be below the published maximum speeds in order to comply with subsequent restrictions - and that's fine since they're max speeds, not "at" speeds. But the most general case is that you'll get fast as quickly as allowed & stay fast as long as allowed. But not in a manner where you slow back down on a departure, nor speed back up on an arrival - unless the controller clears you for it (which is pretty uncommon).

The Jeppesen Charts legend does not go into any detail about these restrictions. It says in general:

SPEED RESTRICTIONS

Speed restrictions that apply to the entire procedure are shown below the procedure title.

Speed restrictions vary widely within individual procedures. They can be in the tabulated text, boxed, and/or placed in information boxes at the associated track, fix or phase of flight.

The exact rules may vary by country. It is my understanding that the constraint is valid until reaching that waypoint on a SID and after reaching it on a STAR.

This is also confirmed by the US AIM:

5-2-9. h. 2. Pilots should not exceed a published speed restriction associated with a SID waypoint until passing that waypoint.

5-4-1. a. 1. STAR procedures may have mandatory speeds and/or crossing altitudes published. [...] Pilots should plan to cross waypoints with a published speed restriction, at the published speed, and should not exceed this speed past the associated waypoint unless authorized by ATC or a published note to do so.

(emphasis mine)