DC9 flight crew experiences multiple electronic equipment failures in flight.

Attributes
ACN	439464
Time
Date	199906
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : lnr.vortac
State Reference	WI
Altitude	msl single value : 31000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zau.artcc
Operator	common carrier : air carrier
Make Model Name	DC-9 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	other vortac
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : flight engineer pilot : commercial pilot : atp pilot : cfi
Experience	flight time last 90 days : 200 flight time total : 16500 flight time type : 6000
ASRS Report	439464
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : instrument pilot : commercial
Events
Anomaly	aircraft equipment problem : critical cabin event : passenger electronic device
Independent Detector	aircraft equipment : tcas aircraft equipment : gpws aircraft equipment : altitude alert other flight crewa other flight crewb
Resolutory Action	aircraft : equipment problem dissipated flight crew : overcame equipment problem
Consequence	other
Supplementary
Problem Areas	Aircraft Flight Crew Human Performance Cabin Crew Human Performance
Primary Problem	Cabin Crew Human Performance

Narrative:

While at cruise flight FL310 we noted the onset of multiple anomalies with independent and interrelated onboard electronic system. The radar altimeter began flagging and sweeping, the GPWS and TCASII annunciated 'fail,' the vors flagged, despite good idents and, by and large, rational signals. Tests of the equipment were otherwise satisfactory so we made announcements requesting that certain ped's (cellphones, pagers, tvs and radios) be verified in a depowered condition, and the flight attendants did a 'ped walk' in the cabin. The problem initially vanished but then reappeared, and we repeated the process this time requesting that all ped's be depowered. The 3RD and final ped walk revealed that several pagers had to be depowered by battery removal, and there was a computer in use with an external battery pack. (No incoming calls to the pagers were admitted to.) after this, the anomalous indications vanished for good and all system operated normally (including on the ground vot signals). We wrote up the indications for maintenance to verify normal indication of affected units.

Original NASA ASRS Text

Title: DC9 FLC EXPERIENCES MULTIPLE ELECTRONIC EQUIP FAILURES IN FLT.

Narrative: WHILE AT CRUISE FLT FL310 WE NOTED THE ONSET OF MULTIPLE ANOMALIES WITH INDEPENDENT AND INTERRELATED ONBOARD ELECTRONIC SYS. THE RADAR ALTIMETER BEGAN FLAGGING AND SWEEPING, THE GPWS AND TCASII ANNUNCIATED 'FAIL,' THE VORS FLAGGED, DESPITE GOOD IDENTS AND, BY AND LARGE, RATIONAL SIGNALS. TESTS OF THE EQUIP WERE OTHERWISE SATISFACTORY SO WE MADE ANNOUNCEMENTS REQUESTING THAT CERTAIN PED'S (CELLPHONES, PAGERS, TVS AND RADIOS) BE VERIFIED IN A DEPOWERED CONDITION, AND THE FLT ATTENDANTS DID A 'PED WALK' IN THE CABIN. THE PROB INITIALLY VANISHED BUT THEN REAPPEARED, AND WE REPEATED THE PROCESS THIS TIME REQUESTING THAT ALL PED'S BE DEPOWERED. THE 3RD AND FINAL PED WALK REVEALED THAT SEVERAL PAGERS HAD TO BE DEPOWERED BY BATTERY REMOVAL, AND THERE WAS A COMPUTER IN USE WITH AN EXTERNAL BATTERY PACK. (NO INCOMING CALLS TO THE PAGERS WERE ADMITTED TO.) AFTER THIS, THE ANOMALOUS INDICATIONS VANISHED FOR GOOD AND ALL SYS OPERATED NORMALLY (INCLUDING ON THE GND VOT SIGNALS). WE WROTE UP THE INDICATIONS FOR MAINT TO VERIFY NORMAL INDICATION OF AFFECTED UNITS.

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.