An medium large transport crew overshot assigned leveloff altitude.

Attributes
ACN	509861
Time
Date	200104
Day	Thu
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : day.airport
State Reference	OH
Altitude	msl bound lower : 11600 msl bound upper : 12500
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	tracon : day.tracon
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Operating Under FAR Part	Part 121
Flight Phase	climbout : vacating altitude
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : multi engine pilot : instrument pilot : commercial pilot : atp
Experience	flight time last 90 days : 100 flight time total : 10000 flight time type : 5000
ASRS Report	509861
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	altitude deviation : overshoot non adherence : clearance other anomaly other
Independent Detector	other flight crewa
Resolutory Action	flight crew : returned to assigned altitude flight crew : became reoriented
Supplementary
Problem Areas	Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Micro sleep. My assigned leveloff altitude was 12000 ft. At 12500 ft, I set my power to 1.15 EPR 60% N1 to establish a 1000 FPM rate of descent to level off at 12000 ft. The proper altitude callout was made by the copilot out of 13000 ft for 12000 ft. I responded 'roger!' night flying is a constant effort to overcome fatigue. I was thinking of my leveloff when the next action was realizing that I was at 11600 ft and corrected back to 12000 ft immediately. This has never happened to me in 36 yrs of flying. I was aware, but not relating for a moment of micro sleep. Both crew members must be fully at attention during descent with more attention to the last 2000 ft of descent. As a measure to correct this problem, a leveloff call should be required, ie, 'level 12000 ft.' 'roger.'

Original NASA ASRS Text

Title: AN MLG CREW OVERSHOT ASSIGNED LEVELOFF ALT.

Narrative: MICRO SLEEP. MY ASSIGNED LEVELOFF ALT WAS 12000 FT. AT 12500 FT, I SET MY PWR TO 1.15 EPR 60% N1 TO ESTABLISH A 1000 FPM RATE OF DSCNT TO LEVEL OFF AT 12000 FT. THE PROPER ALT CALLOUT WAS MADE BY THE COPLT OUT OF 13000 FT FOR 12000 FT. I RESPONDED 'ROGER!' NIGHT FLYING IS A CONSTANT EFFORT TO OVERCOME FATIGUE. I WAS THINKING OF MY LEVELOFF WHEN THE NEXT ACTION WAS REALIZING THAT I WAS AT 11600 FT AND CORRECTED BACK TO 12000 FT IMMEDIATELY. THIS HAS NEVER HAPPENED TO ME IN 36 YRS OF FLYING. I WAS AWARE, BUT NOT RELATING FOR A MOMENT OF MICRO SLEEP. BOTH CREW MEMBERS MUST BE FULLY AT ATTN DURING DSCNT WITH MORE ATTN TO THE LAST 2000 FT OF DSCNT. AS A MEASURE TO CORRECT THIS PROB, A LEVELOFF CALL SHOULD BE REQUIRED, IE, 'LEVEL 12000 FT.' 'ROGER.'

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.