Air carrier descends below assigned altitude.

Attributes
ACN	182927
Time
Date	199107
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : jfk
State Reference	NY
Altitude	msl bound lower : 8000 msl bound upper : 9000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Widebody, Low Wing, 4 Turbojet Eng
Flight Phase	descent other
Route In Use	enroute : on vectors enroute airway : n90
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : flight engineer pilot : commercial pilot : atp
Experience	flight time last 90 days : 120 flight time total : 13673 flight time type : 800
ASRS Report	182927
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : overshoot 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	Pilot Deviation

Narrative:

Step-down descent from FL350 to fl to FL240 to 14000 to 9000' MSL. PF went through 9000' MSL to 8000' and immediately returned to 9000'. Conflict exists as to subsequent clearance to 8000' was given. ATC immediately gave clearance to descend to 4000'. 9000' altitude was set in the altitude alert. Alert was not noticed or failed to sound.

Original NASA ASRS Text

Title: ACR DESCENDS BELOW ASSIGNED ALT.

Narrative: STEP-DOWN DSNT FROM FL350 TO FL TO FL240 TO 14000 TO 9000' MSL. PF WENT THROUGH 9000' MSL TO 8000' AND IMMEDIATELY RETURNED TO 9000'. CONFLICT EXISTS AS TO SUBSEQUENT CLRNC TO 8000' WAS GIVEN. ATC IMMEDIATELY GAVE CLRNC TO DSND TO 4000'. 9000' ALT WAS SET IN THE ALT ALERT. ALERT WAS NOT NOTICED OR FAILED TO SOUND.

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.