A boeing 767-300 descended below the assigned altitude at CCC.

Attributes
ACN	443291
Time
Date	199907
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : ccc.vor
State Reference	NY
Altitude	msl bound lower : 11600 msl bound upper : 12000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zny.artcc
Operator	common carrier : air carrier
Make Model Name	B767-300 and 300 ER
Operating Under FAR Part	Part 121
Navigation In Use	other other vortac
Flight Phase	descent : intermediate altitude
Route In Use	enroute airway : ns.airway
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : cfi pilot : atp pilot : flight engineer pilot : instrument pilot : multi engine pilot : commercial
Experience	flight time last 90 days : 200 flight time total : 8600 flight time type : 1200
ASRS Report	443291
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : multi engine pilot : instrument pilot : flight engineer pilot : commercial
Experience	flight time last 90 days : 105 flight time total : 25000 flight time type : 990
ASRS Report	443190
Events
Anomaly	altitude deviation : overshoot non adherence : clearance
Independent Detector	other controllera other flight crewa
Resolutory Action	flight crew : returned to assigned altitude
Supplementary
Problem Areas	Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

On descent we were cleared to cross CCC at 250 KT/12000 ft. I thought the controller said 9000 ft and set that in the altitude window on the autoplt. The captain was coordinating something with the flight attendant and the relief pilot was finishing a logbook write-up. I was visual with the aircraft in front of us. I noted he had leveled at 12000 ft and mentioned that to the captain who said that's what we're cleared to also. We were at about 11700 ft at this point. I stopped the descent and climbed to 12000 ft. The controller shortly after queried our altitude. We replied 12000 ft but we had briefly gone below. He said no problem, there's no one else in the area. It was my 4TH ocean crossing in 6 days and I hadn't slept too well the night before.

Original NASA ASRS Text

Title: A BOEING 767-300 DSNDED BELOW THE ASSIGNED ALT AT CCC.

Narrative: ON DSCNT WE WERE CLRED TO CROSS CCC AT 250 KT/12000 FT. I THOUGHT THE CTLR SAID 9000 FT AND SET THAT IN THE ALT WINDOW ON THE AUTOPLT. THE CAPT WAS COORDINATING SOMETHING WITH THE FLT ATTENDANT AND THE RELIEF PLT WAS FINISHING A LOGBOOK WRITE-UP. I WAS VISUAL WITH THE ACFT IN FRONT OF US. I NOTED HE HAD LEVELED AT 12000 FT AND MENTIONED THAT TO THE CAPT WHO SAID THAT'S WHAT WE'RE CLRED TO ALSO. WE WERE AT ABOUT 11700 FT AT THIS POINT. I STOPPED THE DSCNT AND CLBED TO 12000 FT. THE CTLR SHORTLY AFTER QUERIED OUR ALT. WE REPLIED 12000 FT BUT WE HAD BRIEFLY GONE BELOW. HE SAID NO PROB, THERE'S NO ONE ELSE IN THE AREA. IT WAS MY 4TH OCEAN XING IN 6 DAYS AND I HADN'T SLEPT TOO WELL THE NIGHT BEFORE.

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.