Altitude deviation altitude overshot - flight crew descends below their clearance altitude.

Attributes
ACN	302121
Time
Date	199504
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : yso airport : yyz
State Reference	ON
Altitude	msl bound lower : 22750 msl bound upper : 23000
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : czyz
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	descent : approach descent other
Route In Use	arrival other arrival star : star enroute airway : czyz
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : flight engineer pilot : atp
Experience	flight time last 90 days : 210 flight time total : 16000 flight time type : 900
ASRS Report	302121
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 150 flight time total : 12500 flight time type : 400
ASRS Report	301866
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : overshoot non adherence : clearance other anomaly other
Independent Detector	other controllera 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	Pilot Deviation

Narrative:

#1 autoplt failed to capture altitude in descent, leveled 250 ft below target altitude. Both #1 flight director and autoplt malfunction in vertical mode. Several times, written upon arrival at detroit.

Original NASA ASRS Text

Title: ALTDEV ALT OVERSHOT - FLC DSNDS BELOW THEIR CLRNC ALT.

Narrative: #1 AUTOPLT FAILED TO CAPTURE ALT IN DSCNT, LEVELED 250 FT BELOW TARGET ALT. BOTH #1 FLT DIRECTOR AND AUTOPLT MALFUNCTION IN VERT MODE. SEVERAL TIMES, WRITTEN UPON ARR AT DETROIT.

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.