AIP ENR 12.3.6 and 12.3.7 is your answer.
Examples:
"ABC, cleared
JENNA 3 arrival , ASPIC transition, Runway 21, instrument procedure, descend F210..." and
(a) nothing else!
(b) "not above 270 knots"
(c) "not above 230 knots"
(d) "best speed, cancel STAR speed restrictions above and below A100"
You then:
(a) descend at your SOP speed, reducing to 250KIAS by A100
(b) fly no faster than 270 knots above A100, reducing to 250 knots by A100
(c) descend at 230 knots, above and below A100. Don't increase speed -- you have been issued a speed limit! (just like Night Watch said).
(d) fly as fast as you like above and below A100 (within aircraft limitations
-------------------------------------------------------------------------------
How do you interpret the speed assignment vs. airspace/procedure requirements for your operations??
First -- ATC don't go issuing speed restrictions for no reason (exception: Darwin ATC
). You are being sequenced for the runway.
So if a speed restriction is issued, although it is possible to be slower, best to stick to the speed you were given (reducing to 250 as applicable).
If you are number 3 in a sequence of 5, you are not being very helpful if you were asked to fly the STAR at 240kts and you reduce to 220 kts fifty miles out. The poor controller will see lovely separation between you and the fellow in front of you, but will be tearing his hair out trying to further slow down/add track miles for the two behind you.
Likewise, its not all that smart to maintain 300kts to the field if it busts airframe limitations, bounces the pax around like flies in a bottle, or has you configuring late, fast and high and going around.
ATC speed instructions are subordinate to flight manual limitations/pax comfort/weather considerations/pilot judgment. Just remember to let them know if you can't give them what they ask for.
