Narrative:

Problem: electromagnetic interference with onboard navigation (VHF) caused by passenger use of portable battery pwred am-FM recorders. Dates: 4/wed/88--departing dfw, climb phase of flight. 4/sat/88--initial cruise after departing dfw. On the dates listed above, we experienced an anomaly in our VOR CDI indications in the magnitude of 3-4 degrees. On the latest occurrence, ATC (fort worth center) informed us that he showed us 4 mi right of course. At the time of this call, our VOR CDI indications were split by 4 degrees, with the capts CDI needle 2 degrees left and coplts showing 2 degrees right of course (dfw VOR 117.0, 078 degrees obs). In both instances of suspected interference, a check of the cabin by the F/a's revealed that there were several portable am-FM recorders or clearance delivery players in use. When their usage was terminated, both VOR CDI indications shifted and agreed, with no deviations/anomaly noted between the 2 separate navigation indicators noted for the remainder of the flts. Recommendations: in light of the fact that the F/a's in-flight manuals do not mention that the use of these devices are prohibited by our company and far 91.19, and the general lack of understanding of their affect upon aircraft navigation, it is recommended that 1) F/a training emphasize this restriction, 2) F/a in-flight reference manuals include this vital information, and 3) pre-departure 'welcome aboard/emergency equipment' passenger announcements include a warning to the passenger that use of portable radios or other electronic devices not preapproved for in-flight use is prohibited. It should be noted that in all cases, passenger were using the cassette recorder playback portion of their radio/recorders. The specific location within the aircraft/make/model and usage was obtained and is available if needed.

Related reports:

Google
 

Original NASA ASRS Text

Title: LGT WAS FOUND OFF COURSE BY ATC.

Narrative: PROBLEM: ELECTROMAGNETIC INTERFERENCE WITH ONBOARD NAV (VHF) CAUSED BY PAX USE OF PORTABLE BATTERY PWRED AM-FM RECORDERS. DATES: 4/WED/88--DEPARTING DFW, CLB PHASE OF FLT. 4/SAT/88--INITIAL CRUISE AFTER DEPARTING DFW. ON THE DATES LISTED ABOVE, WE EXPERIENCED AN ANOMALY IN OUR VOR CDI INDICATIONS IN THE MAGNITUDE OF 3-4 DEGS. ON THE LATEST OCCURRENCE, ATC (FORT WORTH CENTER) INFORMED US THAT HE SHOWED US 4 MI RIGHT OF COURSE. AT THE TIME OF THIS CALL, OUR VOR CDI INDICATIONS WERE SPLIT BY 4 DEGS, WITH THE CAPTS CDI NEEDLE 2 DEGS LEFT AND COPLTS SHOWING 2 DEGS RIGHT OF COURSE (DFW VOR 117.0, 078 DEGS OBS). IN BOTH INSTANCES OF SUSPECTED INTERFERENCE, A CHK OF THE CABIN BY THE F/A'S REVEALED THAT THERE WERE SEVERAL PORTABLE AM-FM RECORDERS OR CD PLAYERS IN USE. WHEN THEIR USAGE WAS TERMINATED, BOTH VOR CDI INDICATIONS SHIFTED AND AGREED, WITH NO DEVIATIONS/ANOMALY NOTED BTWN THE 2 SEPARATE NAV INDICATORS NOTED FOR THE REMAINDER OF THE FLTS. RECOMMENDATIONS: IN LIGHT OF THE FACT THAT THE F/A'S INFLT MANUALS DO NOT MENTION THAT THE USE OF THESE DEVICES ARE PROHIBITED BY OUR COMPANY AND FAR 91.19, AND THE GENERAL LACK OF UNDERSTANDING OF THEIR AFFECT UPON ACFT NAV, IT IS RECOMMENDED THAT 1) F/A TRNING EMPHASIZE THIS RESTRICTION, 2) F/A INFLT REF MANUALS INCLUDE THIS VITAL INFO, AND 3) PRE-DEP 'WELCOME ABOARD/EMER EQUIP' PAX ANNOUNCEMENTS INCLUDE A WARNING TO THE PAX THAT USE OF PORTABLE RADIOS OR OTHER ELECTRONIC DEVICES NOT PREAPPROVED FOR INFLT USE IS PROHIBITED. IT SHOULD BE NOTED THAT IN ALL CASES, PAX WERE USING THE CASSETTE RECORDER PLAYBACK PORTION OF THEIR RADIO/RECORDERS. THE SPECIFIC LOCATION WITHIN THE ACFT/MAKE/MODEL AND USAGE WAS OBTAINED AND IS AVAILABLE IF NEEDED.

Data retrieved from NASA's ASRS site as of August 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.