Originally Posted by
A Squared
Yeah, this. The controller isn't asking you your speed because he's already decided what speed he wants you to maintain and he's reluctant to just come straight out and ask you to maintain it. Controllers are actually pretty good at not asking pointless questions merely as a conversational gambit. He's asking for your speed because it's information he needs, and by not giving him that information he just asked for, you're wasting his time and demonstrating that you don't quite grasp the concept.
Exactly right, A Squared. The controller is asking the question because he needs to adjust either your speed or somebody else's. All he sees are groundspeeds. He has no idea what those translate to in IAS or Mach in your cockpit, and therefore doesn't know yet "what he wants." Maybe someday it will be permissible for a controller to assign groundspeeds. Until then, he needs an answer to the explicit question he asked. Several toolish responses in this thread.