EA30 crew had altitude deviation.

Attributes
ACN	437270
Time
Date	199905
Day	Fri
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : mia.airport
State Reference	FL
Altitude	msl bound lower : 2600 msl bound upper : 3000
Environment
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : mia.tracon
Operator	common carrier : air carrier
Make Model Name	A300
Operating Under FAR Part	Part 121
Navigation In Use	ils localizer only : 30 other
Flight Phase	descent : approach
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	437270
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : instrument pilot : commercial
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude non adherence : clearance
Independent Detector	other flight crewa other flight crewb
Resolutory Action	flight crew : returned to original clearance
Consequence	other
Supplementary
Problem Areas	Aircraft Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Inadvertent descent below assigned altitude. At 20 DME autothrottles disconnected. While troubleshooting the autothrottles problem, with autoplt off, we inadvertently descended 400 ft below assigned altitude. We quickly noticed and immediately returned to assigned altitude. The remainder of the approach was normal.

Original NASA ASRS Text

Title: EA30 CREW HAD ALTDEV.

Narrative: INADVERTENT DSCNT BELOW ASSIGNED ALT. AT 20 DME AUTOTHROTTLES DISCONNECTED. WHILE TROUBLESHOOTING THE AUTOTHROTTLES PROB, WITH AUTOPLT OFF, WE INADVERTENTLY DSNDED 400 FT BELOW ASSIGNED ALT. WE QUICKLY NOTICED AND IMMEDIATELY RETURNED TO ASSIGNED ALT. THE REMAINDER OF THE APCH WAS NORMAL.

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.