Reporter has difficulty complying with ARTCC instructions for speed and altitude restrs.

Attributes
ACN	319250
Time
Date	199510
Day	Wed
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : iiu
State Reference	KY
Altitude	msl bound lower : 11000 msl bound upper : 37000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	artcc : zid
Operator	common carrier : air carrier
Make Model Name	B747-C/F
Operating Under FAR Part	Part 121
Navigation In Use	Other
Flight Phase	descent other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 150 flight time total : 13000 flight time type : 700
ASRS Report	319250
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	altitude deviation : crossing restriction not met altitude deviation : undershoot other anomaly
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance flight crew : returned to intended course or assigned course other
Consequence	faa : reviewed incident with flight crew
Supplementary
Air Traffic Incident	other

Narrative:

We were issued a descent clearance and cross 15 mi west of maize at 11000 ft (maize iio 316 degree radial at 30 NM). We accepted and asked if there would be a speed restr. Answer 'no speed restr.' I set up the descent based on normal speed (.84 mach to 320 KIAS). After the descent was initiated, ATC reclred us to cross the 'fix' (15 mi west of maize) at 280 KTS. I thought, well that's fine, increased the rate of descent (and IAS to about 340-350 KTS). A couple of mins later, center said reduce speed to 310 KTS now. Also fine, however we now can't make the restr. I told them so. The response was 'if you could make it at 280 KTS, why can't you do so at 310 KTS.' I told them we had been given 280 KTS at the fix not in the descent. A bit of an argument took place. Where ATC did (I think) admit they were mistaken. Nevertheless, I had to make a maximum effort descent (brakes out fully) to try to comply as I was unsure if they really waived the speed. I would suggest ATC not change its mind on descent speed once the aircraft has started down as it is very hard to adjust once you are at somewhat of a maximum profile already.

Original NASA ASRS Text

Title: RPTR HAS DIFFICULTY COMPLYING WITH ARTCC INSTRUCTIONS FOR SPD AND ALT RESTRS.

Narrative: WE WERE ISSUED A DSCNT CLRNC AND CROSS 15 MI W OF MAIZE AT 11000 FT (MAIZE IIO 316 DEG RADIAL AT 30 NM). WE ACCEPTED AND ASKED IF THERE WOULD BE A SPD RESTR. ANSWER 'NO SPD RESTR.' I SET UP THE DSCNT BASED ON NORMAL SPD (.84 MACH TO 320 KIAS). AFTER THE DSCNT WAS INITIATED, ATC RECLRED US TO CROSS THE 'FIX' (15 MI W OF MAIZE) AT 280 KTS. I THOUGHT, WELL THAT'S FINE, INCREASED THE RATE OF DSCNT (AND IAS TO ABOUT 340-350 KTS). A COUPLE OF MINS LATER, CTR SAID REDUCE SPD TO 310 KTS NOW. ALSO FINE, HOWEVER WE NOW CAN'T MAKE THE RESTR. I TOLD THEM SO. THE RESPONSE WAS 'IF YOU COULD MAKE IT AT 280 KTS, WHY CAN'T YOU DO SO AT 310 KTS.' I TOLD THEM WE HAD BEEN GIVEN 280 KTS AT THE FIX NOT IN THE DSCNT. A BIT OF AN ARGUMENT TOOK PLACE. WHERE ATC DID (I THINK) ADMIT THEY WERE MISTAKEN. NEVERTHELESS, I HAD TO MAKE A MAX EFFORT DSCNT (BRAKES OUT FULLY) TO TRY TO COMPLY AS I WAS UNSURE IF THEY REALLY WAIVED THE SPD. I WOULD SUGGEST ATC NOT CHANGE ITS MIND ON DSCNT SPD ONCE THE ACFT HAS STARTED DOWN AS IT IS VERY HARD TO ADJUST ONCE YOU ARE AT SOMEWHAT OF A MAX PROFILE ALREADY.

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.