Minor aircraft equipment problem creates an altitude deviation altitude overshot in descent.

Attributes
ACN	297140
Time
Date	199502
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : las
State Reference	NV
Altitude	msl bound lower : 23650 msl bound upper : 24000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zla
Operator	common carrier : air carrier
Make Model Name	L-1011-500 Series
Operating Under FAR Part	other : unknown
Navigation In Use	Other Other
Flight Phase	descent other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : flight engineer pilot : atp
Experience	flight time last 90 days : 150 flight time total : 9000 flight time type : 1800
ASRS Report	297140
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : flight engineer pilot : commercial pilot : atp
Experience	flight time last 90 days : 172 flight time total : 16000 flight time type : 2000
ASRS Report	297133
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : overshoot non adherence : clearance
Independent Detector	other flight crewa
Resolutory Action	flight crew : returned to intended course or assigned course flight crew : overcame equipment problem
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation

Narrative:

Autoplt failed to capture FL240 in descent. Failure was noticed at FL240 and correction was initiated. Aircraft descended to 23,650 ft before positive rate of climb was achieved. Clearance to FL190 was received at about the time the correction was initiated. Supplemental information from acn 297133: initiated immediate level off. In attempt to level off and be smooth I descended through FL240 to approximately 23650 ft and immediately back up to FL240. Also, had requested lower (than FL240) and controller was in process of clearing us on down to FL190. Corrective action: monitor aircraft in autoplt mode more closely and avoid complacency on beautiful clear days. Supplemental information from acn 297141: descent to 29000 ft MSL. Descended to 28650 ft maximum deviation during hands on manual correction.

Original NASA ASRS Text

Title: MINOR ACFT EQUIP PROB CREATES AN ALTDEV ALT OVERSHOT IN DSCNT.

Narrative: AUTOPLT FAILED TO CAPTURE FL240 IN DSCNT. FAILURE WAS NOTICED AT FL240 AND CORRECTION WAS INITIATED. ACFT DSNDED TO 23,650 FT BEFORE POSITIVE RATE OF CLB WAS ACHIEVED. CLRNC TO FL190 WAS RECEIVED AT ABOUT THE TIME THE CORRECTION WAS INITIATED. SUPPLEMENTAL INFO FROM ACN 297133: INITIATED IMMEDIATE LEVEL OFF. IN ATTEMPT TO LEVEL OFF AND BE SMOOTH I DSNDED THROUGH FL240 TO APPROX 23650 FT AND IMMEDIATELY BACK UP TO FL240. ALSO, HAD REQUESTED LOWER (THAN FL240) AND CTLR WAS IN PROCESS OF CLRING US ON DOWN TO FL190. CORRECTIVE ACTION: MONITOR ACFT IN AUTOPLT MODE MORE CLOSELY AND AVOID COMPLACENCY ON BEAUTIFUL CLR DAYS. SUPPLEMENTAL INFO FROM ACN 297141: DSCNT TO 29000 FT MSL. DSNDED TO 28650 FT MAX DEV DURING HANDS ON MANUAL CORRECTION.

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.