NAV AND COM RADIO PROB; SUSPECTED EMI FROM PAX'S USE OF PORTABLE TELEPHONE.

Narrative

FLT WAS UNEVENTFUL THROUGH APPROX 15000 FT; FLYING THE GENEVA 2 DEP FROM DTW TO DCA; RECEIVING BOTH DXO (113.4) AND YQG (113.8) VORS NORMALLY. WHEN CHANGING TO THE ACO (114.4) VOR NEITHER THE CAPT OR FO NAVAID; RECEIVED THE VOR SIGNAL PROPERLY; 58 DME FROM THE STATION. BOTH VOR'S NAVAID GIVING ABNORMAL INDICATIONS OF HAVING AN OCCASIONAL INTERMITTENT RED FLAG; WITH A VOR BEARING PLUS OR MINUS 20-30 DEGS; EITHER SIDE OF THE APPROX COURSE; WITH THE CDI NEEDLE MOVING BACK AND FORTH ACROSS THE INST CASE SLOWLY; THE IDENT SIGNAL WAS AUDIBLE BUT HAD INTERFERENCE; BOTH VOR'S NAVAID HAD SAME INDICATIONS. BOTH DME'S WORKED NORMALLY. STILL CLBING TO ASSIGNED ALT OF FL270. ASKED ZOB FOR A HDG DIRECT NEXT FIX OF AIR (117.1) VOR. WE WERE GIVEN A HDG UNTIL RECEIVING AIR (117.1) VOR; THE SAME ABNORMAL INSTRUMENTATION OCCURRED ON BOTH CAPT'S AND FO'S VOR; THE DME WORKED NORMALLY ON BOTH SIDES AND SHOWED APPROX 125 DME FROM AIR (117.1) VOR. ZOB ADVISED US THEY HAD NO RPTED PROBS WITH AIR (117.1) VOR. WHILE MAINTAINING THE ASSIGNED HDG WE CHKED THE OTHER LCL VORS AROUND OUR POS AND FOUND THAT WE GOT THE SAME ABNORMAL INST INDICATIONS ON THE CAPT'S AND FO'S SIDE. SENSING THAT OUR PROB WAS POSSIBLY CAUSED BY AN ELECTRONIC DEVICE OPERATED BY A PAX ON BOARD; THE LEAD FLT ATTENDANT WAS INSTRUCTED TO CHK THE TYPES OF ELECTRONIC EQUIP BEING OPERATED BY THE PAX. THE FLT ATTENDANT RETURNED AND ADVISED US THAT SHE SAW ONE PAX OPERATING A 'SONY MAGIC LINK; PIC 1000.' THIS DEVICE WAS NOT PLUGGED INTO THE ACFT'S ONBOARD PHONE SYS; BUT WAS BEING OPERATED BY ITSELF WITH ITS OWN BATTERIES. HE WAS ASKED TO PLEASE TURN IT OFF AND PUT IT AWAY. BY THE TIME THE FLT ATTENDANT HAD RETURNED TO THE COCKPIT; BOTH VORS HAD RETURNED TO OPERATING NORMALLY. AFTER A SHORT PERIOD OF NORMAL OPS AT CRUISE ALT OF FL270; ENRTE TO ESL (110.8) VOR; BOTH VORS WERE INTERMITTENTLY STARTING TO ACT UP AND SHOW THE SAME ABNORMAL INSTRUMENTATION; -- BRIEFLY; THEN WOULD RETURN TO NORMAL FOR A LONGER PERIOD OF TIME; THEN BACK TOABNORMAL. IT WAS AS THOUGH A PAX WAS USING AN ELECTRONIC DEVICE FOR 1-3 MINS CAUSING THE INTERFERENCE; THEN TURNING THE DEVICE OFF FOR SHORT DURATION; THEN REUSING IT AGAIN. KEY NOTE YOU COULD TELL WHEN YOU HAD THE ABNORMAL INSTRUMENTATION BY LISTENING TO THE IDENT AND HEARING THE INTERFERENCE BUT WOULD STILL HEAR THE IDENT WEAKLY. NOTE YOU WOULD NOT ALWAYS HAVE A RED FLAG; BUT THE VOR NEEDLE WOULD APPEAR TO BE SCALLOPING L AND R OF COURSE. I CALL THIS SEMI-ABNORMAL INSTRUMENTATION DURING THE TIME YOU WOULD HAVE NO RED FLAG ON THE INST; BUT THE VOR'S NEEDLES WOULD BE FLUCTUATING L AND R; AND COULD HEAR THE IDENT WEAKLY WITH INTERFERENCE. DURING THIS TIME OF SEMI-ABNORMAL INSTRUMENTATION WE WERE AT FL270; 15 MI W OF ESL (110.8) VOR ON THE BUCKO 4 ARR TO DCA. ZDC ASKED US WHEN WE WERE GOING TO START OUR DSCNT. WE ADVISED ZDC WE HAD BEEN GIVEN NO DSCNT; WHAT WOULD THEY LIKE US TO DO? WE WERE ADVISED TO START DOWN TO 15000 FT AND WE COMPLIED WITH THE REQUEST. EVERYTHING APPEARED TO BE NORMAL AND WE ARE NOW ENRTE TO AML (113.5) VOR AT AN ALT OF 11000 FT APPROX 33 MI OUT OF AML (113.5) VOR AT TRIXY WITH ANOTHER BRIEF ENCOUNTER WITH SEMI-ABNORMAL INSTRUMENTATION WHICH RESULTED IN ME STARTING MY TURN LATE INTERCEPTING THE AML (113.5) VOR 300 DEG RADIAL. AT 10 MI W OF AML (113.5) VOR WE WERE ASKED IF WE ARE GOING TO MAKE THE 8000 FT ALT AT AML (113.5) VOR; WE ADVISED ZDC WE NEVER GOT AN ALT CLRNC. WE THEN WERE GIVEN A R TURN FOR SPACING; THEN TOLD TO DSND TO 8000 FT AND COMPLIED. THERE IS A GOOD POSSIBILITY THAT THE INTERFERENCE AFFECTED VHF COMS AS WELL AS THE VOR NAV SINCE ATC HAD ATTEMPTED COM TWICE WITH AN ALT CLRNC; AT DIFFERENT TIMES AND NEITHER THE CAPT OR MYSELF HEARD THE DSCNT CLRNCS. CONCLUSION: SUSPECT THAT THE ACFT NAV VOR AND/OR COM RADIOS WERE INTERFERED WITH BY SOME SOURCE; MOST LIKELY AN ELECTRONIC DEVICE SUCH AS A CELL PHONE; PAGER; ETC; BEING USED BY A PAX. SUPPLEMENTAL INFO FROM ACN 318606: WHEN FLYING THE SAME ACFT THE NEXT DAY BOTH NAV RADIOS OPERATED NORMALLY.