Aircraft equipment problem -- altitude deviation altitude excursion -- air carrier has an omega fault that affects the autoflt and instrument system causing an altitude deviation.

Home

Browse by month

Random

Latest

About

Contact

Attributes
ACN	312650
Time
Date	199508
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : pxr
State Reference	AZ
Altitude	msl bound lower : 34700 msl bound upper : 35200
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zab
Operator	common carrier : air carrier
Make Model Name	MD-80 Super 80
Operating Under FAR Part	Part 121
Navigation In Use	Other
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
ASRS Report	312650
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	312649
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 : overcame equipment problem flight crew : returned to intended course or assigned course
Consequence	Other

Narrative:

At approximately XA25Z, aug/tue/95 while flying at FL350 approximately 20 mi ese of pxr VOR ZAB frequency 132.45 in clear smooth air the omega TAS fail message appeared for 1-2 seconds and then the autoplt and autothrottles disengaged. The captain's mach indication increased from .76 to .86 and the mach off flag appeared. Captain flying assumed control. The aircraft began to climb on first officer's altimeter and standby altimeter while captain's altimeter remained steady with no flags. After approximately 200 ft climb the captain's altimeter jumped and froze again. Captain's ivsi showed approximately 800 FPM climb as nose was lowered. Aircraft began descent as captain's instruments continued to show a climb with no flags. First officer assumed control and stopped descent approximately 300 ft low and returned to FL350. Autoplt #2 selected. ATC was called and informed of problem. He responded that it was no problem as there was no traffic in our vicinity. In approximately 15 seconds captain's system recovered and seemed to work normally for remainder of flight.

Original NASA ASRS Text

Title: ACFT EQUIP PROB -- ALTDEV ALT EXCURSION -- ACR HAS AN OMEGA FAULT THAT AFFECTS THE AUTOFLT AND INST SYS CAUSING AN ALTDEV.

Narrative: AT APPROX XA25Z, AUG/TUE/95 WHILE FLYING AT FL350 APPROX 20 MI ESE OF PXR VOR ZAB FREQ 132.45 IN CLR SMOOTH AIR THE OMEGA TAS FAIL MESSAGE APPEARED FOR 1-2 SECONDS AND THEN THE AUTOPLT AND AUTOTHROTTLES DISENGAGED. THE CAPT'S MACH INDICATION INCREASED FROM .76 TO .86 AND THE MACH OFF FLAG APPEARED. CAPT FLYING ASSUMED CTL. THE ACFT BEGAN TO CLB ON FO'S ALTIMETER AND STANDBY ALTIMETER WHILE CAPT'S ALTIMETER REMAINED STEADY WITH NO FLAGS. AFTER APPROX 200 FT CLB THE CAPT'S ALTIMETER JUMPED AND FROZE AGAIN. CAPT'S IVSI SHOWED APPROX 800 FPM CLB AS NOSE WAS LOWERED. ACFT BEGAN DSCNT AS CAPT'S INSTS CONTINUED TO SHOW A CLB WITH NO FLAGS. FO ASSUMED CTL AND STOPPED DSCNT APPROX 300 FT LOW AND RETURNED TO FL350. AUTOPLT #2 SELECTED. ATC WAS CALLED AND INFORMED OF PROB. HE RESPONDED THAT IT WAS NO PROB AS THERE WAS NO TFC IN OUR VICINITY. IN APPROX 15 SECONDS CAPT'S SYS RECOVERED AND SEEMED TO WORK NORMALLY FOR REMAINDER OF FLT.

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.