That seems to be the norm when departing LAX. The key words they use are "when able maintain 280 kts". You are legally able to leaving 10,000 feet.

Just to add to the discussion, in the Galapagos of aviation that is Australia, you can ask for or be given a cancellation of speed restrictions. This allows you to fly as fast as you want below 10k. Sydney will do this late at night when curfew is rapidly approaching. 330 kts to join a 5 mile final.

That link supports exactly what I said. If your clean speed is greater that 250, you can fly at the higher speed below 10,000 and you don't need to ask.

They expect you to maintain 250 until 10K, and only then accelerate to 280. Actually the controllers don't really care, they'd probably be happy if you went faster sooner (but the FAA cares...).

A controller cannot waive the FARs, but they assume you know this.

They don't always say "when able". But I know what they mean.

Alder is correct. You can climb at clean maneuvering speed in the US without permission or advising ATC. It does not, however, excuse you from speed restrictions on a departure procedure that you accepted. For a maxxed out 74 it could be 320+ kts.

Every country is different and must be referenced.

Hmm my reply got left off, was agreeing with you and giving the reference.

Check your company regs as well. Ours states 250kts or operational speeds below 10,000'

If ATC wants you faster than 250/operational/"normal" speeds below 10,000' they will tell you. That way it is also recorded "for your protection". I would rather be told to speed up below 10,000' than be busted for going too fast based on an "interpretation", of what things should be.

TERPS will limit speeds below 10,000' on departures/arrivals in CAT C & D aircraft of 290 its due to radius of turn issues.

The window structural limits are also something to take into consideration. You are more likely to take a bird strike below 10'000' than above.

As to VHHH departures - "cancel speed restrictions" my thought process would be when you are FULLY established on the outbound track from ROVER/PORPA to RAMEN or conversely PRAWN to RUMSY you can speed up past the 220/230 kt limit. This limit is specifically for terrain clearance. If HK wants you faster than 250 below 10 they will tell you, (I have had this happen). A lot is dependent on what your altitude is on the departure (being held lower for inbound traffic) and MVA's

Lots of regs, with lots of interpretations, especially in international operations. I'd rather hear the "speed up" verses the "why are you so fast" ATC conversation.

320+ knots?? For clean maneuvering? Not just Econ climb?

I've flown a 747-400 at max takeoff (875,000 pounds) and 747-8 at close to max (955,000 pounds, max is 990,000) and have never been anywhere near 320. 280-290 is more realistic from what I've seen.