A flight crew slows on an approach and the approach controller said they were not cleared to slow.

Attributes
ACN	520510
Time
Date	200108
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : den.airport
State Reference	CO
Altitude	msl single value : 13000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	descent : approach
Route In Use	approach : visual
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : multi engine pilot : atp
Experience	flight time last 90 days : 60 flight time total : 12000 flight time type : 4700
ASRS Report	520510
Events
Anomaly	non adherence : clearance other anomaly
Resolutory Action	controller : issued new clearance
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	ATC Human Performance Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance

Narrative:

While being vectored for a visual approach, at approximately 17 NM from den airport, the first officer (PF) began a speed reduction to 220 KTS (per our profile). Approach control queried us on our speed. We advised slowing to 220 KTS. Approach control then asked if we had been assigned 220 KTS. We told him no. He then advised us that our crossing speed at the arrival fix (some 35 mi from the airport) was our last assigned speed -- 250 KTS. The controller then cleared us to slow to 210 KTS and to descend to 11000 ft, then handed us off to the final controller. I have been operating into dia at den for 10 yrs and this was the first time I have been corrected for this type of speed reduction. Our flight manual profiles provide for stabilized, controled dscnts, and, to my understanding, ZDV and our flight operations representatives have met on numerous occasions to discuss just this issue. I do not know if a loss of separation actually occurred, but the approach controller was very concerned about our speed reduction. In the future, I will always ask for a reduction before accomplishing one.

Original NASA ASRS Text

Title: A FLT CREW SLOWS ON AN APCH AND THE APCH CTLR SAID THEY WERE NOT CLRED TO SLOW.

Narrative: WHILE BEING VECTORED FOR A VISUAL APCH, AT APPROX 17 NM FROM DEN ARPT, THE FO (PF) BEGAN A SPD REDUCTION TO 220 KTS (PER OUR PROFILE). APCH CTL QUERIED US ON OUR SPD. WE ADVISED SLOWING TO 220 KTS. APCH CTL THEN ASKED IF WE HAD BEEN ASSIGNED 220 KTS. WE TOLD HIM NO. HE THEN ADVISED US THAT OUR XING SPD AT THE ARR FIX (SOME 35 MI FROM THE ARPT) WAS OUR LAST ASSIGNED SPD -- 250 KTS. THE CTLR THEN CLRED US TO SLOW TO 210 KTS AND TO DSND TO 11000 FT, THEN HANDED US OFF TO THE FINAL CTLR. I HAVE BEEN OPERATING INTO DIA AT DEN FOR 10 YRS AND THIS WAS THE FIRST TIME I HAVE BEEN CORRECTED FOR THIS TYPE OF SPD REDUCTION. OUR FLT MANUAL PROFILES PROVIDE FOR STABILIZED, CTLED DSCNTS, AND, TO MY UNDERSTANDING, ZDV AND OUR FLT OPS REPRESENTATIVES HAVE MET ON NUMEROUS OCCASIONS TO DISCUSS JUST THIS ISSUE. I DO NOT KNOW IF A LOSS OF SEPARATION ACTUALLY OCCURRED, BUT THE APCH CTLR WAS VERY CONCERNED ABOUT OUR SPD REDUCTION. IN THE FUTURE, I WILL ALWAYS ASK FOR A REDUCTION BEFORE ACCOMPLISHING ONE.

Data retrieved from NASA's ASRS site as of July 2007 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.