<< >> NASA ASRS Report 245796, July 1993

Got a 'heading' flag on HSI (both) when taxiing into position, again during takeoff roll. This HSI error lasted into cruise; a passenger had been using a cellular phone.

Attributes
ACN	245796
Time
Date	199307
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : dfw
State Reference	TX
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : dfw tower : dsm
Operator	common carrier : air carrier
Make Model Name	Light Transport, Low Wing, 2 Turboprop Eng
Navigation In Use	Other
Flight Phase	climbout : initial climbout : takeoff ground other : taxi
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 240 flight time total : 8000 flight time type : 650
ASRS Report	245796
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	other flight crewa
Resolutory Action	flight crew : overcame equipment problem
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

While taxiing into position for takeoff, got 'heading' flag -- ahrs warning on ehsi's (both). Reset normally. Occurred again during takeoff roll and would not reset. 20 degree error between left and right system. After initial level off, unsuccessfully tried all means of realigning compass system. Having read recent articles on EMI, finally asked flight attendant to check if any passenger were using electronic devices. Almost immediately ahrs 'heading' warning disappeared and ehsi's realigned. Flight attendant reported 1 passenger was using a cellular telephone. In retrospect, I have had numerous instances similar to this one which mysteriously corrected themselves after a period of time.

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Original NASA ASRS Text

Title: GOT A 'HDG' FLAG ON HSI (BOTH) WHEN TAXIING INTO POS, AGAIN DURING TKOF ROLL. THIS HSI ERROR LASTED INTO CRUISE; A PAX HAD BEEN USING A CELLULAR PHONE.

Narrative: WHILE TAXIING INTO POS FOR TKOF, GOT 'HDG' FLAG -- AHRS WARNING ON EHSI'S (BOTH). RESET NORMALLY. OCCURRED AGAIN DURING TKOF ROLL AND WOULD NOT RESET. 20 DEG ERROR BTWN L AND R SYS. AFTER INITIAL LEVEL OFF, UNSUCCESSFULLY TRIED ALL MEANS OF REALIGNING COMPASS SYS. HAVING READ RECENT ARTICLES ON EMI, FINALLY ASKED FLT ATTENDANT TO CHK IF ANY PAX WERE USING ELECTRONIC DEVICES. ALMOST IMMEDIATELY AHRS 'HDG' WARNING DISAPPEARED AND EHSI'S REALIGNED. FLT ATTENDANT RPTED 1 PAX WAS USING A CELLULAR TELEPHONE. IN RETROSPECT, I HAVE HAD NUMEROUS INSTANCES SIMILAR TO THIS ONE WHICH MYSTERIOUSLY CORRECTED THEMSELVES AFTER A PERIOD OF TIME.

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.