B737-700 flight crew reported they misunderstood the clearance and airspeed given to them by ATC.

Attributes
ACN	1412307
Time
Date	201612
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Light	Dusk
Aircraft 1
Make Model Name	B737-700
Operating Under FAR Part	Part 121
Flight Phase	Descent
Flight Plan	IFR
Person 1
Function	Pilot Not Flying First Officer
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 194
Person 2
Function	Pilot Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 113
Events
Anomaly	ATC Issue All Types Deviation - Procedural Clearance Deviation - Speed All Types

Narrative:

We were descending into ZZZ and thought we were given a clearance to cross ZZZ VOR at FL240 and 250 knots. Our previous clearance was to maintain mach .75. The controller queried us as to our indicated airspeed. I replied 270 knots. She responded we were given 250 knots and immediately gave us a turn for traffic. I told her I understood the clearance to be cross ZZZ VOR at 250 knots at FL240. She responded that was not what we were told. I figured it best not to argue and only complied with her instructions. We were given a direct to clearance a minute or two later and were never given a number to call.

Original NASA ASRS Text

Title: B737-700 flight crew reported they misunderstood the clearance and airspeed given to them by ATC.

Narrative: We were descending into ZZZ and thought we were given a clearance to cross ZZZ VOR at FL240 and 250 knots. Our previous clearance was to maintain Mach .75. The Controller queried us as to our indicated airspeed. I replied 270 knots. She responded we were given 250 knots and immediately gave us a turn for traffic. I told her I understood the clearance to be cross ZZZ VOR at 250 knots at FL240. She responded that was not what we were told. I figured it best not to argue and only complied with her instructions. We were given a direct to clearance a minute or two later and were never given a number to call.

Data retrieved from NASA's ASRS site 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.