When I’m operating as Tower or Approach, a lot of pilots would come in too fast, above 250 kt while they are below 10,000 feet. They’re not supposed to do that, so sometimes I tell them “Maintain slowest possible speed” since Tower cannot specify the exact speed.
On the other hand, when I watch planes in the real-world landing sequence on Flightradar24, I noticed that a lot of them are doing 260-290 kt on approach and sometimes even 320-340 kt on departure, all well below 10,000 feet. That’s at VHHK.
So is there really a strict speed limit in the real world and is it enforced?
Yes but in real life if the controller gives you permission to a break that rule then you could go about 250kts under 10,000 feet (this command isn’t in infinite flight).
There is a speed limit of 250kts below 10,000ft. This is largely due to the high amount of birds and planes below 10,000ft. The speed limit servers as a way to increase reaction time if you do see a bird or plane so that you can avoid it. The limit is not necessarily about the population it is more about avoiding collisions. This speed limit is enforced at least at my airport.
ATC tells you to maintain 250 knots. IF does not give you violations if your speed is below 260 knots below 10000 feet, gusts can make your speed go high, but then the gusts slow down and you return to normal speed again, so really no problem.