Altitude deviation. Overshoot in climb. Excursion from assigned altitude.

Attributes
ACN	148798
Time
Date	199006
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : cyn
State Reference	NJ
Altitude	msl bound lower : 21600 msl bound upper : 22300
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zny
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other
Flight Phase	climbout : intermediate altitude
Route In Use	enroute airway : j110
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : cfi
Experience	flight time last 90 days : 165 flight time total : 7200 flight time type : 95
ASRS Report	148798
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 180 flight time total : 15000 flight time type : 180
ASRS Report	148969
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude altitude deviation : overshoot non adherence : clearance
Independent Detector	other controllera other flight crewa
Resolutory Action	flight crew : overcame equipment problem flight crew : returned to intended course or assigned course
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

While operating medium large transport via the digital FGS with autoplt coupled, aircraft was attempting to capture assigned altitude of FL220. Aircraft did not capture assigned altitude and the climb was arrested at FL223. Further inputs into the FGS were made with a resultant altitude deviation to FL216. Manual control of aircraft was taken from the autoplt system. Aircraft was climbed back to assigned FL220. Further investigation revealed that the digital FGS and autoplt system would not duplicate the previously mentioned uncommanded altitude excursions. As a crew, we were somewhat disturbed that system balked. Before we were able to advise ATC, the altitude deviation was announced by the controller. His alertness should be commended. However, due to the short duration of this incident, we were unable to alert the controller in a more expeditious manner. When reengagement of the autoplt was attempted, it performed in a satisfactory manner. Close observation was continued for the remainder of the flight. The correct altitude had been entered into the system with the proper procedures. I have no clue as to the lack of system performance for this short period.

Original NASA ASRS Text

Title: ALT DEVIATION. OVERSHOOT IN CLIMB. EXCURSION FROM ASSIGNED ALT.

Narrative: WHILE OPERATING MLG VIA THE DIGITAL FGS WITH AUTOPLT COUPLED, ACFT WAS ATTEMPTING TO CAPTURE ASSIGNED ALT OF FL220. ACFT DID NOT CAPTURE ASSIGNED ALT AND THE CLB WAS ARRESTED AT FL223. FURTHER INPUTS INTO THE FGS WERE MADE WITH A RESULTANT ALT DEVIATION TO FL216. MANUAL CTL OF ACFT WAS TAKEN FROM THE AUTOPLT SYS. ACFT WAS CLBED BACK TO ASSIGNED FL220. FURTHER INVESTIGATION REVEALED THAT THE DIGITAL FGS AND AUTOPLT SYS WOULD NOT DUPLICATE THE PREVIOUSLY MENTIONED UNCOMMANDED ALT EXCURSIONS. AS A CREW, WE WERE SOMEWHAT DISTURBED THAT SYS BALKED. BEFORE WE WERE ABLE TO ADVISE ATC, THE ALT DEVIATION WAS ANNOUNCED BY THE CTLR. HIS ALERTNESS SHOULD BE COMMENDED. HOWEVER, DUE TO THE SHORT DURATION OF THIS INCIDENT, WE WERE UNABLE TO ALERT THE CTLR IN A MORE EXPEDITIOUS MANNER. WHEN REENGAGEMENT OF THE AUTOPLT WAS ATTEMPTED, IT PERFORMED IN A SATISFACTORY MANNER. CLOSE OBSERVATION WAS CONTINUED FOR THE REMAINDER OF THE FLT. THE CORRECT ALT HAD BEEN ENTERED INTO THE SYS WITH THE PROPER PROCS. I HAVE NO CLUE AS TO THE LACK OF SYS PERFORMANCE FOR THIS SHORT PERIOD.

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.