EMI interference causes a split between the aircraft's compass system in flight.

Attributes
ACN	283859
Time
Date	199409
Day	Sat
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : ewc
State Reference	PA
Altitude	msl bound lower : 33000 msl bound upper : 33000
Environment
Flight Conditions	IMC
Light	Night
Aircraft 1
Controlling Facilities	artcc : zob tower : mdw
Operator	common carrier : air carrier
Make Model Name	MD-88
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 100 flight time total : 3600 flight time type : 1100
ASRS Report	283859
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : critical other anomaly other other spatial deviation
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa other other : unspecified
Resolutory Action	flight crew : overcame equipment problem
Consequence	Other
Supplementary
Air Traffic Incident	other

Narrative:

Twice while in cruise flight got 15 degree heading split between #1 and #2 compass system. Unable to determine which/both system was affected. Split lasted approximately 5 mins. Each time flight attendant confirmed a first class passenger was using a laptop computer. It was a toshiba model 'satellite 1960 ct.' we asked passenger to turn it off and no further heading splits occurred. Due to flight duties we were unable to further test/diagnose the problem. We flew exact same aircraft for 2 more flts (5 1/2 hours) with no other compass splits. This is my third occurrence of suspected personal electronic device interference. Each time on this aircraft, md-88, it seems to produce a 15 degree heading split.

Original NASA ASRS Text

Title: EMI INTERFERENCE CAUSES A SPLIT BTWN THE ACFT'S COMPASS SYS IN FLT.

Narrative: TWICE WHILE IN CRUISE FLT GOT 15 DEG HDG SPLIT BTWN #1 AND #2 COMPASS SYS. UNABLE TO DETERMINE WHICH/BOTH SYS WAS AFFECTED. SPLIT LASTED APPROX 5 MINS. EACH TIME FLT ATTENDANT CONFIRMED A FIRST CLASS PAX WAS USING A LAPTOP COMPUTER. IT WAS A TOSHIBA MODEL 'SATELLITE 1960 CT.' WE ASKED PAX TO TURN IT OFF AND NO FURTHER HDG SPLITS OCCURRED. DUE TO FLT DUTIES WE WERE UNABLE TO FURTHER TEST/DIAGNOSE THE PROB. WE FLEW EXACT SAME ACFT FOR 2 MORE FLTS (5 1/2 HRS) WITH NO OTHER COMPASS SPLITS. THIS IS MY THIRD OCCURRENCE OF SUSPECTED PERSONAL ELECTRONIC DEVICE INTERFERENCE. EACH TIME ON THIS ACFT, MD-88, IT SEEMS TO PRODUCE A 15 DEG HDG SPLIT.

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.