Narrative:

When I made the comment that the 10 KTS did not make a difference; I was referring to spacing on aircraft ahead. The controller could just have easily had vectored us a few degrees off course or turned us at a different location for final. Final center controller directed us to slow to 210 KTS prior to bearz. We informed her unable as clean minimum maneuvering speed was 220 KTS. She stated ok; she'd pass that along to TRACON. Upon checking in with TRACON he ordered 210 KTS. Again we stated unable. He was obstinate about it and we told him unable 2 more times before finally just rogering him. This is an unsafe attitude on the controller's part. When a pilot replies unable to a clearance; that should be the end of it. In our situation; the 10 KTS made no difference; other than the controller had the attitude that he was in ultimate control of our aircraft. I have seen this happen more and more where controllers are starting to order aircraft around with disregard for the safe and efficient operation of our aircraft. I would strongly suggest we get the controllers back in the cockpit jumpseats to gain a better understanding of our aircraft system and limitations.

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Original NASA ASRS Text

Title: B767 FLT CREW STATES 'UNABLE' WHEN INSTRUCTED TO SLOW TO 210 KNOTS 40 NM FROM ARPT DUE TO EFFICIENCY REASONS.

Narrative: WHEN I MADE THE COMMENT THAT THE 10 KTS DID NOT MAKE A DIFFERENCE; I WAS REFERRING TO SPACING ON ACFT AHEAD. THE CTLR COULD JUST HAVE EASILY HAD VECTORED US A FEW DEGS OFF COURSE OR TURNED US AT A DIFFERENT LOCATION FOR FINAL. FINAL CTR CTLR DIRECTED US TO SLOW TO 210 KTS PRIOR TO BEARZ. WE INFORMED HER UNABLE AS CLEAN MINIMUM MANEUVERING SPD WAS 220 KTS. SHE STATED OK; SHE'D PASS THAT ALONG TO TRACON. UPON CHKING IN WITH TRACON HE ORDERED 210 KTS. AGAIN WE STATED UNABLE. HE WAS OBSTINATE ABOUT IT AND WE TOLD HIM UNABLE 2 MORE TIMES BEFORE FINALLY JUST ROGERING HIM. THIS IS AN UNSAFE ATTITUDE ON THE CTLR'S PART. WHEN A PLT REPLIES UNABLE TO A CLRNC; THAT SHOULD BE THE END OF IT. IN OUR SIT; THE 10 KTS MADE NO DIFFERENCE; OTHER THAN THE CTLR HAD THE ATTITUDE THAT HE WAS IN ULTIMATE CTL OF OUR ACFT. I HAVE SEEN THIS HAPPEN MORE AND MORE WHERE CTLRS ARE STARTING TO ORDER ACFT AROUND WITH DISREGARD FOR THE SAFE AND EFFICIENT OP OF OUR ACFT. I WOULD STRONGLY SUGGEST WE GET THE CTLRS BACK IN THE COCKPIT JUMPSEATS TO GAIN A BETTER UNDERSTANDING OF OUR ACFT SYS AND LIMITATIONS.

Data retrieved from NASA's ASRS site as of May 2009 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.