Narrative:

While en route at FL230, ATC issued the following instruction/clearance: '...reduce speed to 190 KTS for in trail spacing....' we were approaching an inbound fix, as were other aircraft, and preparing for descent. Our conditions were IMC and the aircraft had structural ice accumulating. The instruction/clearance was refused with the explanation about the ice accumulation (91.3). No further discussion or problem that I am aware of, nor any adverse situation arose between flight crew and ATC. But there is a problem! Not just ZME, but many other ATC facilities have issued similar clrncs/instructions with the expectation and the compliance by the flight crew. Someone in ATC has forgotten the prescribed minima in the 7110.65 handbook. I.e., chapter 5 radar section and speed adjustment, paragraph 5-102(a) 'to aircraft operating between FL280 and 10000 ft, a speed not less than 250 KTS....' also in the aim, ATC clrncs/separation, paragraph 272 speed adjustments D(1) 'same.'

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Original NASA ASRS Text

Title: AN ACR LTT CREW REFUSED AN AIRSPD CHANGE THAT WAS CONTRARY TO INSTRUCTIONS IN THE CTLR'S HANDBOOK.

Narrative: WHILE ENRTE AT FL230, ATC ISSUED THE FOLLOWING INSTRUCTION/CLRNC: '...REDUCE SPD TO 190 KTS FOR IN TRAIL SPACING....' WE WERE APCHING AN INBOUND FIX, AS WERE OTHER ACFT, AND PREPARING FOR DSCNT. OUR CONDITIONS WERE IMC AND THE ACFT HAD STRUCTURAL ICE ACCUMULATING. THE INSTRUCTION/CLRNC WAS REFUSED WITH THE EXPLANATION ABOUT THE ICE ACCUMULATION (91.3). NO FURTHER DISCUSSION OR PROB THAT I AM AWARE OF, NOR ANY ADVERSE SIT AROSE BTWN FLC AND ATC. BUT THERE IS A PROB! NOT JUST ZME, BUT MANY OTHER ATC FACILITIES HAVE ISSUED SIMILAR CLRNCS/INSTRUCTIONS WITH THE EXPECTATION AND THE COMPLIANCE BY THE FLC. SOMEONE IN ATC HAS FORGOTTEN THE PRESCRIBED MINIMA IN THE 7110.65 HANDBOOK. I.E., CHAPTER 5 RADAR SECTION AND SPD ADJUSTMENT, PARAGRAPH 5-102(A) 'TO ACFT OPERATING BTWN FL280 AND 10000 FT, A SPD NOT LESS THAN 250 KTS....' ALSO IN THE AIM, ATC CLRNCS/SEPARATION, PARAGRAPH 272 SPD ADJUSTMENTS D(1) 'SAME.'

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.