Narrative:

After a routine scheduled flight from ord to dtw, we were being vectored for an ILS approach to runway 21R at dtw. The ATIS gave the WX as 300 ft overcast and 1 mi visibility. After intercepting the localizer we were cleared for the approach. Approximately 12 mi out from the runway, the first officer's GS and localizer 'off' flags came into view (he was the PF). A few seconds later, mine (captain's) also went off the air (ILS localizer/GS). We both tried to get the morse code identify. But both navigation receivers seemed dead. We asked approach control to take us off the approach so we could check the thing out. While being vectored, both our navigation receivers came back on, also with the morse code identify. We both figured the ground signal had been interrupted, even though the controller had said that his equipment was working ok. We elected to try another approach. Again, just outside the OM both our navigation receivers went off the air. I asked to be vectored to holding, while I contacted our dispatcher. During that time I tried other ILS frequencys, and got the same 'off' flags and no identify. Occasionally, they would come back on the air but go off. We decided to divert to cle where the WX was VFR. A normal approach and landing was made there. Where the aircraft would remain overnight for maintenance. During our dilemma, I told our lead flight attendant of our problem, and that we were going to cle. She made a PA to passenger to turn off any electronic equipment if it were being used. We had no further problems. I am still baffled about this, as the dc-9 uses 2 separate ILS navigation receivers. I am still wondering if a passenger did have some electronic device on at the time we made our approachs to dtw.

Related reports:

Google
 

Original NASA ASRS Text

Title: DURING 2 ILS APCH ATTEMPTS, BOTH LOC AND GS OFF FLAGS SHOWED JUST PRIOR TO THE OM AND THE IDENT COULD NOT BE HEARD ON BOTH THE FO AND CAPT'S RECEIVERS OF A DC-9 TYPE ACFT.

Narrative: AFTER A ROUTINE SCHEDULED FLT FROM ORD TO DTW, WE WERE BEING VECTORED FOR AN ILS APCH TO RWY 21R AT DTW. THE ATIS GAVE THE WX AS 300 FT OVCST AND 1 MI VISIBILITY. AFTER INTERCEPTING THE LOC WE WERE CLRED FOR THE APCH. APPROX 12 MI OUT FROM THE RWY, THE FO'S GS AND LOC 'OFF' FLAGS CAME INTO VIEW (HE WAS THE PF). A FEW SECONDS LATER, MINE (CAPT'S) ALSO WENT OFF THE AIR (ILS LOC/GS). WE BOTH TRIED TO GET THE MORSE CODE IDENT. BUT BOTH NAV RECEIVERS SEEMED DEAD. WE ASKED APCH CTL TO TAKE US OFF THE APCH SO WE COULD CHK THE THING OUT. WHILE BEING VECTORED, BOTH OUR NAV RECEIVERS CAME BACK ON, ALSO WITH THE MORSE CODE IDENT. WE BOTH FIGURED THE GND SIGNAL HAD BEEN INTERRUPTED, EVEN THOUGH THE CTLR HAD SAID THAT HIS EQUIP WAS WORKING OK. WE ELECTED TO TRY ANOTHER APCH. AGAIN, JUST OUTSIDE THE OM BOTH OUR NAV RECEIVERS WENT OFF THE AIR. I ASKED TO BE VECTORED TO HOLDING, WHILE I CONTACTED OUR DISPATCHER. DURING THAT TIME I TRIED OTHER ILS FREQS, AND GOT THE SAME 'OFF' FLAGS AND NO IDENT. OCCASIONALLY, THEY WOULD COME BACK ON THE AIR BUT GO OFF. WE DECIDED TO DIVERT TO CLE WHERE THE WX WAS VFR. A NORMAL APCH AND LNDG WAS MADE THERE. WHERE THE ACFT WOULD REMAIN OVERNIGHT FOR MAINT. DURING OUR DILEMMA, I TOLD OUR LEAD FLT ATTENDANT OF OUR PROB, AND THAT WE WERE GOING TO CLE. SHE MADE A PA TO PAX TO TURN OFF ANY ELECTRONIC EQUIP IF IT WERE BEING USED. WE HAD NO FURTHER PROBS. I AM STILL BAFFLED ABOUT THIS, AS THE DC-9 USES 2 SEPARATE ILS NAV RECEIVERS. I AM STILL WONDERING IF A PAX DID HAVE SOME ELECTRONIC DEVICE ON AT THE TIME WE MADE OUR APCHS TO DTW.

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.