BelArgUSA - LanFranc is saying that it is possible to safely operate a 747 at 250kts on climb, and he is of course correct. As you know, to do this, you'd need to have probably Flap 1, which isn't necessarily
efficient but certainly possible.
I do agree with you, however, that +100 is what I call an operational requirement, and so tell ATC and fly that speed. London has been quite clever and granted a dispensation to 747's to fly at 280kts if required... less radio calls, less fuss. Some other airports state a speed restriction of 250kts or Min Clean Speed. Again, removes the fuss.
As to the US pilot thing... we were rather confused out of a major European airport when after takeoff, ATC would say "High Speed Approved", when we didn't think there was a speed limit! Further investigations got the answer that the phrase was used to remind US based airlines that they could go fast. Smart controllers!
