A B727 first officer reported an air data computer failure near cqy, causing a track deviation.

Attributes
ACN	511180
Time
Date	200105
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : cqy.vortac
State Reference	TX
Environment
Light	Daylight
Aircraft 1
Controlling Facilities	tower : sjc.tower
Operator	common carrier : air carrier
Make Model Name	B727 Undifferentiated or Other Model
Flight Phase	descent : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
ASRS Report	511180
Events
Anomaly	aircraft equipment problem : critical non adherence : far non adherence : company policies non adherence : clearance other spatial deviation
Resolutory Action	none taken : detected after the fact
Consequence	other
Supplementary
Problem Areas	Flight Crew Human Performance Aircraft
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Air data computer failed in-flight, making pilot's altimeter, airspeed, altitude alerter, autoplt, and navigation coupling inoperative. During simultaneous airspeed and altitude changes, overflew cqy by 10 mi, missing course change to 309 degrees. ATC advised of deviation. No traffic conflict reported.

Original NASA ASRS Text

Title: A B727 FO RPTED AN AIR DATA COMPUTER FAILURE NEAR CQY, CAUSING A TRACK DEV.

Narrative: AIR DATA COMPUTER FAILED INFLT, MAKING PLT'S ALTIMETER, AIRSPD, ALT ALERTER, AUTOPLT, AND NAV COUPLING INOP. DURING SIMULTANEOUS AIRSPD AND ALT CHANGES, OVERFLEW CQY BY 10 MI, MISSING COURSE CHANGE TO 309 DEGS. ATC ADVISED OF DEV. NO TFC CONFLICT RPTED.

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.