EMB145 captain reports misunderstanding a descent clearance with a crossing restriction based on dis...

Narrative:

We were cruising at FL280 and were instructed by center to cross 20 miles south of mzz VOR at FL260 and increase speed from 270 KIAS to 280 KIAS. I read back the instructions. I'm not sure if I read back FL260 or FL200. But the first officer set FL200 as the altitude to descend to and I verified. As we were descending through FL250 to meet the crossing restriction ATC asked us to maintain FL260. I queried him on our clearance; which I thought; and the first officer thought; was FL200; but he said it was FL260. He then asked us to level off at FL240. We continued the flight with no other issues.the way the controller read the instructions; there were a lot of 'numbers' I had to remember and I feel I mixed them up. With the 20 mile crossing restriction; the altitude change the speed increase all in one breath; I mixed them up and instead of FL260 we used FL200. Another threat to the flight was that we were on our 5th of 6 legs for the day and had been dealing with winter operations the whole day making the day feel longer. I learned that next time I get a long clearance in one breath I should double check with the controller to make sure I read back all the instructions correctly. I should also double check with the first officer to make sure he heard what I heard.

Original NASA ASRS Text

Title: EMB145 Captain reports misunderstanding a descent clearance with a crossing restriction based on distance and a speed adjustment. The First Officer misunderstands in a similar fashion and the clearance is not questioned; resulting in as descent below assigned altitude.

Narrative: We were cruising at FL280 and were instructed by Center to cross 20 miles south of MZZ VOR at FL260 and increase speed from 270 KIAS to 280 KIAS. I read back the instructions. I'm not sure if I read back FL260 or FL200. But the First Officer set FL200 as the altitude to descend to and I verified. As we were descending through FL250 to meet the crossing restriction ATC asked us to maintain FL260. I queried him on our clearance; which I thought; and the First Officer thought; was FL200; but he said it was FL260. He then asked us to level off at FL240. We continued the flight with no other issues.The way the Controller read the instructions; there were a lot of 'numbers' I had to remember and I feel I mixed them up. With the 20 mile crossing restriction; the altitude change the speed increase all in one breath; I mixed them up and instead of FL260 we used FL200. Another threat to the flight was that we were on our 5th of 6 legs for the day and had been dealing with winter operations the whole day making the day feel longer. I learned that next time I get a long clearance in one breath I should double check with the controller to make sure I read back all the instructions correctly. I should also double check with the First Officer to make sure he heard what I heard.

Data retrieved from NASA's ASRS site as of July 2013 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.

Attributes
ACN	1068739
Time
Date	201302
Local Time Of Day	1201-1800
Place
Locale Reference	ZAU.ARTCC
State Reference	IL
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	EMB ERJ 145 ER/LR
Operating Under FAR Part	Part 121
Flight Phase	Descent
Flight Plan	IFR
Person 1
Function	Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Deviation - Altitude Overshoot Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy

EMB145 captain reports misunderstanding a descent clearance with a crossing restriction based on distance and a speed adjustment. The first officer misunderstands in a similar fashion and the clearance is not questioned; resulting in as descent below assigned altitude.