Air carrier medium large transport track headintg deviation. The FMC had failed and the flight crew says they are not accustomed to tracking an airway using 'just charts'.

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Attributes
ACN	152852
Time
Date	199007
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : ott
State Reference	MD
Altitude	msl bound lower : 28000 msl bound upper : 28000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdc tower : apa
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	cruise other
Route In Use	enroute airway : j191 enroute airway : j193
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 10000 flight time type : 4000
ASRS Report	152852
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : private pilot : flight engineer pilot : commercial pilot : atp
Experience	flight time last 90 days : 155 flight time total : 5000 flight time type : 2500
ASRS Report	152667
Events
Anomaly	aircraft equipment problem : less severe non adherence : clearance other spatial deviation
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance flight crew : returned to intended course or assigned course other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

FMC inoperative after takeoff (screen blank). Crew had to continually enter magnetic heading confusion as to what was working and what wasn't. PNF misread chart and instructed PF to track J-191 instead of J-193 at the divergence point of these 2 arwys. Center advised that we were 7 mi west of J-193 and diverging. Intercept heading issued and we resumed correct navigation. Contributing factors. Failure to pay attention to details on my part. Confusion regarding FMC failure. Not seen that often where the screen is completely blank. Had become unaccustomed to explicitly following jet arwys from a chart rather than relying on FMC and IRS. Crew coordination, PF not challenging an obvious error by the PIC. Supplemental information from acn 152667. At hubbs intersection we had a double FMC failure. With the arwys becoming more condensed it is very easy to misread an arwy right to a VOR. We have excellent en route charts, but sometimes the charts can be cluttered with too much information.

Original NASA ASRS Text

Title: ACR MLG TRACK HEADINTG DEVIATION. THE FMC HAD FAILED AND THE FLT CREW SAYS THEY ARE NOT ACCUSTOMED TO TRACKING AN AIRWAY USING 'JUST CHARTS'.

Narrative: FMC INOPERATIVE AFTER TKOF (SCREEN BLANK). CREW HAD TO CONTINUALLY ENTER MAGNETIC HDG CONFUSION AS TO WHAT WAS WORKING AND WHAT WASN'T. PNF MISREAD CHART AND INSTRUCTED PF TO TRACK J-191 INSTEAD OF J-193 AT THE DIVERGENCE POINT OF THESE 2 ARWYS. CTR ADVISED THAT WE WERE 7 MI W OF J-193 AND DIVERGING. INTERCEPT HDG ISSUED AND WE RESUMED CORRECT NAV. CONTRIBUTING FACTORS. FAILURE TO PAY ATTN TO DETAILS ON MY PART. CONFUSION REGARDING FMC FAILURE. NOT SEEN THAT OFTEN WHERE THE SCREEN IS COMPLETELY BLANK. HAD BECOME UNACCUSTOMED TO EXPLICITLY FOLLOWING JET ARWYS FROM A CHART RATHER THAN RELYING ON FMC AND IRS. CREW COORD, PF NOT CHALLENGING AN OBVIOUS ERROR BY THE PIC. SUPPLEMENTAL INFO FROM ACN 152667. AT HUBBS INTXN WE HAD A DOUBLE FMC FAILURE. WITH THE ARWYS BECOMING MORE CONDENSED IT IS VERY EASY TO MISREAD AN ARWY R TO A VOR. WE HAVE EXCELLENT ENRTE CHARTS, BUT SOMETIMES THE CHARTS CAN BE CLUTTERED WITH TOO MUCH INFO.

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.