Commuter aircraft starts descent to wrong altitude. Radar controller catches the error.

Attributes
ACN	335546
Time
Date	199605
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : mkc
State Reference	MO
Altitude	msl bound lower : 9600 msl bound upper : 10000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zkc
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	descent other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial pilot : cfi
Experience	flight time last 90 days : 200 flight time total : 1800 flight time type : 700
ASRS Report	335546
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : overshoot altitude deviation : excursion from assigned altitude
Independent Detector	other controllera
Resolutory Action	flight crew : became reoriented flight crew : returned to intended course or assigned course other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

I was the first officer on a commuter flight from oma to mci. I was the PNF. We received a crossing restr into kansas city. What I thought I heard was to cross 35 mi from mkc VOR at 8000 ft. I believe this is what I read back. But when we reached 9600 ft ATC asked what altitude we were at. And that there was crossing traffic 7 mi away at 9000 ft and that he told us to cross at 10000 ft not 8000 ft. And I did read that back to him. I still believe I read back 8000 ft. After talking to my captain, she said that she did think she had heard ATC tell us 10000 ft and not 8000 ft. My question then is why she kept descending down to 8000 ft. As we are a scheduled carrier, going into mci we always get a crossing restr to cross around 40 mi out at 8000 ft. So I may have just thought he said 8000 ft but indeed he did say 10000 ft. The other contributing factor may be that the captain and I were having a discussion on various items and may have just missed the different altitude that we are used to.

Original NASA ASRS Text

Title: COMMUTER ACFT STARTS DSCNT TO WRONG ALT. RADAR CTLR CATCHES THE ERROR.

Narrative: I WAS THE FO ON A COMMUTER FLT FROM OMA TO MCI. I WAS THE PNF. WE RECEIVED A XING RESTR INTO KANSAS CITY. WHAT I THOUGHT I HEARD WAS TO CROSS 35 MI FROM MKC VOR AT 8000 FT. I BELIEVE THIS IS WHAT I READ BACK. BUT WHEN WE REACHED 9600 FT ATC ASKED WHAT ALT WE WERE AT. AND THAT THERE WAS XING TFC 7 MI AWAY AT 9000 FT AND THAT HE TOLD US TO CROSS AT 10000 FT NOT 8000 FT. AND I DID READ THAT BACK TO HIM. I STILL BELIEVE I READ BACK 8000 FT. AFTER TALKING TO MY CAPT, SHE SAID THAT SHE DID THINK SHE HAD HEARD ATC TELL US 10000 FT AND NOT 8000 FT. MY QUESTION THEN IS WHY SHE KEPT DSNDING DOWN TO 8000 FT. AS WE ARE A SCHEDULED CARRIER, GOING INTO MCI WE ALWAYS GET A XING RESTR TO CROSS AROUND 40 MI OUT AT 8000 FT. SO I MAY HAVE JUST THOUGHT HE SAID 8000 FT BUT INDEED HE DID SAY 10000 FT. THE OTHER CONTRIBUTING FACTOR MAY BE THAT THE CAPT AND I WERE HAVING A DISCUSSION ON VARIOUS ITEMS AND MAY HAVE JUST MISSED THE DIFFERENT ALT THAT WE ARE USED TO.

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.