An air carrier light transport had an altitude deviation attributable to an ah-rs failure.

Attributes
ACN	267848
Time
Date	199403
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : iah
State Reference	TX
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : iah
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	other other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 210 flight time total : 13750
ASRS Report	267848
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
ASRS Report	267906
Events
Anomaly	aircraft equipment problem : critical altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other
Independent Detector	other flight crewa
Resolutory Action	flight crew : overcame equipment problem other
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation other

Narrative:

Following an ah-rs failure and vectors for a 'return' landing we descended 800 ft below our assigned altitude (note: pitch control ah-rs) was a factor. There was no conflict of traffic and we were following an A300 heavy to the active runway with visual contact. It may be noted that after ah-rs 2 was selected and the pitch difference between ca/first officer resolved, 20 degrees versus 8 degrees, altitude control was no problem at all. The items lost in this failure were 1) altitude information on captain side (pitch), 2) command bars, 3) heading bars, 4) autoplt, 5) yaw dampener. All cockpit resource management procedures were used and the result was a very normal return and landing. Strongly recommend cockpit resource management to all!

Original NASA ASRS Text

Title: AN ACR LTT HAD AN ALT DEV ATTRIBUTABLE TO AN AH-RS FAILURE.

Narrative: FOLLOWING AN AH-RS FAILURE AND VECTORS FOR A 'RETURN' LNDG WE DSNDED 800 FT BELOW OUR ASSIGNED ALT (NOTE: PITCH CTL AH-RS) WAS A FACTOR. THERE WAS NO CONFLICT OF TFC AND WE WERE FOLLOWING AN A300 HVY TO THE ACTIVE RWY WITH VISUAL CONTACT. IT MAY BE NOTED THAT AFTER AH-RS 2 WAS SELECTED AND THE PITCH DIFFERENCE BTWN CA/FO RESOLVED, 20 DEGS VERSUS 8 DEGS, ALT CTL WAS NO PROB AT ALL. THE ITEMS LOST IN THIS FAILURE WERE 1) ALT INFO ON CAPT SIDE (PITCH), 2) COMMAND BARS, 3) HDG BARS, 4) AUTOPLT, 5) YAW DAMPENER. ALL COCKPIT RESOURCE MGMNT PROCS WERE USED AND THE RESULT WAS A VERY NORMAL RETURN AND LNDG. STRONGLY RECOMMEND COCKPIT RESOURCE MGMNT TO ALL!

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.