Flight crew allows aircraft to deviate 200 ft from assigned altitude.

Attributes
ACN	314620
Time
Date	199508
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : tpa
State Reference	FL
Altitude	msl bound lower : 3800 msl bound upper : 4000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : tpa
Operator	common carrier : air carrier
Make Model Name	MD-90-30
Operating Under FAR Part	Part 121
Flight Phase	cruise other descent : approach
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : commercial
Experience	flight time last 90 days : 150 flight time total : 23960 flight time type : 1400
ASRS Report	314620
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance
Independent Detector	other flight crewa
Resolutory Action	flight crew : returned to intended course or assigned course
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	other

Narrative:

We were maintaining 4000 ft MSL. For some reason the first officer, who was flying, began descending below our assigned altitude of 4000 ft. I caught the airplane at 3800 ft MSL and climbed back to 4000 ft. The entire event lasted less than 10 seconds. ATC did not comment on the altitude loss, but his tone of voice seemed more irritated with us. There were other aircraft in the area, but I don't think a traffic conflict was created. Crew fatigue may have been a factor in this event.

Original NASA ASRS Text

Title: FLC ALLOWS ACFT TO DEVIATE 200 FT FROM ASSIGNED ALT.

Narrative: WE WERE MAINTAINING 4000 FT MSL. FOR SOME REASON THE FO, WHO WAS FLYING, BEGAN DSNDING BELOW OUR ASSIGNED ALT OF 4000 FT. I CAUGHT THE AIRPLANE AT 3800 FT MSL AND CLBED BACK TO 4000 FT. THE ENTIRE EVENT LASTED LESS THAN 10 SECONDS. ATC DID NOT COMMENT ON THE ALT LOSS, BUT HIS TONE OF VOICE SEEMED MORE IRRITATED WITH US. THERE WERE OTHER ACFT IN THE AREA, BUT I DON'T THINK A TFC CONFLICT WAS CREATED. CREW FATIGUE MAY HAVE BEEN A FACTOR IN THIS EVENT.

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.