<< >> NASA ASRS Report 331150, March 1996

Altitude deviation. First officer flying using #2 air data computer and autoplt, air data computer failed, aircraft climbed 800 ft before flight crew disconnected autoplt and returned to assigned altitude.

Attributes
ACN	331150
Time
Date	199603
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : zdv
State Reference	CO
Altitude	msl bound lower : 33000 msl bound upper : 33800
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdv
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 220 flight time total : 16000 flight time type : 1900
ASRS Report	331150
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 250 flight time total : 4800 flight time type : 870
ASRS Report	331307
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified 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:

After experiencing an air data computer failure #2 and setting source select knob to #1 and transferring autoplt to flight data 1 the air data computer reset showing normal indications. So we switched back to normal on the source select then transferred the autoplt flight director back to #2 after 15 seconds or so, just long enough to be satisfied it would be ok and look away. The air data computer #2 failed again and the nose pitched up gaining 700-800 ft before the autoplt was disconnected and altitude reestablished.

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Original NASA ASRS Text

Title: ALTDEV. FO FLYING USING #2 AIR DATA COMPUTER AND AUTOPLT, ADC FAILED, ACFT CLBED 800 FT BEFORE FLC DISCONNECTED AUTOPLT AND RETURNED TO ASSIGNED ALT.

Narrative: AFTER EXPERIENCING AN AIR DATA COMPUTER FAILURE #2 AND SETTING SOURCE SELECT KNOB TO #1 AND TRANSFERRING AUTOPLT TO FLT DATA 1 THE AIR DATA COMPUTER RESET SHOWING NORMAL INDICATIONS. SO WE SWITCHED BACK TO NORMAL ON THE SOURCE SELECT THEN TRANSFERRED THE AUTOPLT FLT DIRECTOR BACK TO #2 AFTER 15 SECONDS OR SO, JUST LONG ENOUGH TO BE SATISFIED IT WOULD BE OK AND LOOK AWAY. THE AIR DATA COMPUTER #2 FAILED AGAIN AND THE NOSE PITCHED UP GAINING 700-800 FT BEFORE THE AUTOPLT WAS DISCONNECTED AND ALT REESTABLISHED.

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.