An air carrier B727 flight crew report that they had difficulty tracking a VOR signal and they suspe...

Attributes
ACN	386260
Time
Date	199711
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : ldn
State Reference	VA
Altitude	msl bound lower : 11000 msl bound upper : 11000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdc
Operator	common carrier : air carrier
Make Model Name	B727 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	cruise other descent other
Route In Use	arrival other arrival star : star
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : flight engineer pilot : instrument
Experience	flight time last 90 days : 210 flight time total : 10000 flight time type : 4900
ASRS Report	386260
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	non adherence : published procedure other anomaly other other spatial deviation
Independent Detector	aircraft equipment other aircraft equipment : unspecified other controllera other flight crewa
Resolutory Action	controller : issued new clearance other
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

We were on the jasen 1 arrival to dallas, descending on the arnel 259 degree radial to intercept the linden 206 degree radial. Shortly after we leveled at 11000 ft and well before my VOR indicated arrival at the ldn radial, the controller advised that we were going to miss the intersection by about 6 mi and began to vector us. Prior to this point, the captain's VOR had been wavering back and forth slowly, though it appeared he was doing a good job of flying the average indication. As soon as approach advised us of the problem, he retuned my VOR to aml, and it became apparent that the magnitude of his VOR oscillations was much greater than mine (about +/-3 degrees versus 1/2 degrees). However, as we got closer to dallas, both receivers appeared to settle down rather suddenly, and operations on the ILS and on the ground with ldn retuned appeared normal. Our next leg was wbound over roughly the same route as the arrival. Both vors air checked normally. Possible problem could have been interference from a laptop computer or other passenger electronics. The arrival got too busy to have flight attendants do an extra check in the air, but discussion with them after landing indicated a laptop had been in use, and passenger were known to surreptitiously use other devices on this leg. Unfortunately, due to dallas' unique passenger system, it was not possible to delay the person with the laptop to do a ground check.

Original NASA ASRS Text

Title: AN ACR B727 FLC RPT THAT THEY HAD DIFFICULTY TRACKING A VOR SIGNAL AND THEY SUSPECT THAT INTERFERENCE FROM A PAX'S COMPUTER MAY HAVE BEEN THE CAUSE. THE ARTCC CTLR GAVE THE FLC VECTORS ON COURSE.

Narrative: WE WERE ON THE JASEN 1 ARR TO DALLAS, DSNDING ON THE ARNEL 259 DEG RADIAL TO INTERCEPT THE LINDEN 206 DEG RADIAL. SHORTLY AFTER WE LEVELED AT 11000 FT AND WELL BEFORE MY VOR INDICATED ARR AT THE LDN RADIAL, THE CTLR ADVISED THAT WE WERE GOING TO MISS THE INTXN BY ABOUT 6 MI AND BEGAN TO VECTOR US. PRIOR TO THIS POINT, THE CAPT'S VOR HAD BEEN WAVERING BACK AND FORTH SLOWLY, THOUGH IT APPEARED HE WAS DOING A GOOD JOB OF FLYING THE AVERAGE INDICATION. AS SOON AS APCH ADVISED US OF THE PROB, HE RETUNED MY VOR TO AML, AND IT BECAME APPARENT THAT THE MAGNITUDE OF HIS VOR OSCILLATIONS WAS MUCH GREATER THAN MINE (ABOUT +/-3 DEGS VERSUS 1/2 DEGS). HOWEVER, AS WE GOT CLOSER TO DALLAS, BOTH RECEIVERS APPEARED TO SETTLE DOWN RATHER SUDDENLY, AND OPS ON THE ILS AND ON THE GND WITH LDN RETUNED APPEARED NORMAL. OUR NEXT LEG WAS WBOUND OVER ROUGHLY THE SAME RTE AS THE ARR. BOTH VORS AIR CHKED NORMALLY. POSSIBLE PROB COULD HAVE BEEN INTERFERENCE FROM A LAPTOP COMPUTER OR OTHER PAX ELECTRONICS. THE ARR GOT TOO BUSY TO HAVE FLT ATTENDANTS DO AN EXTRA CHK IN THE AIR, BUT DISCUSSION WITH THEM AFTER LNDG INDICATED A LAPTOP HAD BEEN IN USE, AND PAX WERE KNOWN TO SURREPTITIOUSLY USE OTHER DEVICES ON THIS LEG. UNFORTUNATELY, DUE TO DALLAS' UNIQUE PAX SYS, IT WAS NOT POSSIBLE TO DELAY THE PERSON WITH THE LAPTOP TO DO A GND CHK.

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.

An air carrier B727 flight crew report that they had difficulty tracking a VOR signal and they suspect that interference from a passenger's computer may have been the cause. The ARTCC controller gave the flight crew vectors on course.