Narrative:

We were operating under IFR in accordance with the last clearance received from ord approach control. Direct cgt VOR, V-7, beebe intersection, direct ord; maintain 8000'. Just after passing cgt and turning to join V-7 northbound, both the copilot and I clearly heard on the frequency (125.7), 'small aircraft, heading 180 degree' (the arwy course is 356 degree). The copilot responded, 'small aircraft, heading 180 degree (or heading 180 degree, small aircraft)'. There was no answer to his confirmation. Although we both thought this clearance was odd, and briefly discussed it, we began the turn as cleared. Had we been operating in any airspace other than chicago, I probably would have questioned it before accepting it; however, the chicago airspace is so busy that there is usually little chance for such question. Because a 180 degree heading would have taken us within about 8 NM directly into a cloud bank, I asked the controller, during the turn, how far he was going to take us on the new heading. Either he, or someone, replied with something like 'not far, let me know when you need to turn.' while passing about a 270 degree heading, it became obvious that 180 degree was not going to work, given our proximity to the WX, and I requested a 250 degree heading instead. This seemed to cause confusion on the part of the controller, who then told us to maintain a 360 degree heading, then 010 degree and to advise him the next time we needed to deviate for WX. I replied that we very well understood that requirement, but that we had been assigned a 180 degree heading, which prompted my concern with the WX. At this point, the controller indicated that he had not issued such a clearance. The remainder of the vectoring and sequencing to the runway 4R ILS at ord was essentially normal, except that in the turn back to 360 degree, the controller asked us whether we were turning left or right (it was right, the closest direction) and told us to recycle our transponder. Just prior to handoff to ord tower, I asked the controller if he had any idea what had happened and he replied that there had been recent reports of spurious xmissions on the approach frequency, and that he and another controller had been discussing this. My concern in filing this report is not to avoid certificate action, because I do not think that the flight crew erred, and I believe that the frequency tape would show this. Rather, I am sincerely concerned that someone may be playing 'pranks' on a very busy ATC frequency. The potential for disaster is obvious. In our case, we were operating in VMC, and there were no aircraft near us, at our altitude, which could have created a conflict situation. However, this is certainly not the norm near O'hare. My only suggestion (which I intend to implement myself) is to question any clearance which seems very odd (if given without a reason), no matter where I'm flying. It seems that a simple repeat of the clearance, with aircraft identify, is not sufficient in some cases. Callback conversation with reporter revealed the following information. Contacted the air traffic manager at ord in reference to the reporter's receiving a phantom ATC clearance. The manager was aware of the incidents. He informed me that they (pilots) were getting a phantom ATC clearance about once a month. He stated that the controllers could not hear the clearance to the pilots. Controllers and supervisors have been briefed and they are watching for abnormal turns by the flcs. The fbi/FCC are trying to track the source of the phantom clrncs. Great lakes region has purchased a D/F van to locate the person making the phantom ATC clrncs. Every effort is being made to eliminate source.

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Original NASA ASRS Text

Title: PLT RECEIVED PHANTOM ATC CLRNC.

Narrative: WE WERE OPERATING UNDER IFR IN ACCORDANCE WITH THE LAST CLRNC RECEIVED FROM ORD APCH CTL. DIRECT CGT VOR, V-7, BEEBE INTXN, DIRECT ORD; MAINTAIN 8000'. JUST AFTER PASSING CGT AND TURNING TO JOIN V-7 NBND, BOTH THE COPLT AND I CLRLY HEARD ON THE FREQ (125.7), 'SMA, HDG 180 DEG' (THE ARWY COURSE IS 356 DEG). THE COPLT RESPONDED, 'SMA, HDG 180 DEG (OR HDG 180 DEG, SMA)'. THERE WAS NO ANSWER TO HIS CONFIRMATION. ALTHOUGH WE BOTH THOUGHT THIS CLRNC WAS ODD, AND BRIEFLY DISCUSSED IT, WE BEGAN THE TURN AS CLRED. HAD WE BEEN OPERATING IN ANY AIRSPACE OTHER THAN CHICAGO, I PROBABLY WOULD HAVE QUESTIONED IT BEFORE ACCEPTING IT; HOWEVER, THE CHICAGO AIRSPACE IS SO BUSY THAT THERE IS USUALLY LITTLE CHANCE FOR SUCH QUESTION. BECAUSE A 180 DEG HDG WOULD HAVE TAKEN US WITHIN ABOUT 8 NM DIRECTLY INTO A CLOUD BANK, I ASKED THE CTLR, DURING THE TURN, HOW FAR HE WAS GOING TO TAKE US ON THE NEW HDG. EITHER HE, OR SOMEONE, REPLIED WITH SOMETHING LIKE 'NOT FAR, LET ME KNOW WHEN YOU NEED TO TURN.' WHILE PASSING ABOUT A 270 DEG HDG, IT BECAME OBVIOUS THAT 180 DEG WAS NOT GOING TO WORK, GIVEN OUR PROX TO THE WX, AND I REQUESTED A 250 DEG HDG INSTEAD. THIS SEEMED TO CAUSE CONFUSION ON THE PART OF THE CTLR, WHO THEN TOLD US TO MAINTAIN A 360 DEG HDG, THEN 010 DEG AND TO ADVISE HIM THE NEXT TIME WE NEEDED TO DEVIATE FOR WX. I REPLIED THAT WE VERY WELL UNDERSTOOD THAT REQUIREMENT, BUT THAT WE HAD BEEN ASSIGNED A 180 DEG HDG, WHICH PROMPTED MY CONCERN WITH THE WX. AT THIS POINT, THE CTLR INDICATED THAT HE HAD NOT ISSUED SUCH A CLRNC. THE REMAINDER OF THE VECTORING AND SEQUENCING TO THE RWY 4R ILS AT ORD WAS ESSENTIALLY NORMAL, EXCEPT THAT IN THE TURN BACK TO 360 DEG, THE CTLR ASKED US WHETHER WE WERE TURNING L OR R (IT WAS R, THE CLOSEST DIRECTION) AND TOLD US TO RECYCLE OUR XPONDER. JUST PRIOR TO HDOF TO ORD TWR, I ASKED THE CTLR IF HE HAD ANY IDEA WHAT HAD HAPPENED AND HE REPLIED THAT THERE HAD BEEN RECENT RPTS OF SPURIOUS XMISSIONS ON THE APCH FREQ, AND THAT HE AND ANOTHER CTLR HAD BEEN DISCUSSING THIS. MY CONCERN IN FILING THIS RPT IS NOT TO AVOID CERTIFICATE ACTION, BECAUSE I DO NOT THINK THAT THE FLC ERRED, AND I BELIEVE THAT THE FREQ TAPE WOULD SHOW THIS. RATHER, I AM SINCERELY CONCERNED THAT SOMEONE MAY BE PLAYING 'PRANKS' ON A VERY BUSY ATC FREQ. THE POTENTIAL FOR DISASTER IS OBVIOUS. IN OUR CASE, WE WERE OPERATING IN VMC, AND THERE WERE NO ACFT NEAR US, AT OUR ALT, WHICH COULD HAVE CREATED A CONFLICT SITUATION. HOWEVER, THIS IS CERTAINLY NOT THE NORM NEAR O'HARE. MY ONLY SUGGESTION (WHICH I INTEND TO IMPLEMENT MYSELF) IS TO QUESTION ANY CLRNC WHICH SEEMS VERY ODD (IF GIVEN WITHOUT A REASON), NO MATTER WHERE I'M FLYING. IT SEEMS THAT A SIMPLE REPEAT OF THE CLRNC, WITH ACFT IDENT, IS NOT SUFFICIENT IN SOME CASES. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO. CONTACTED THE AIR TFC MGR AT ORD IN REFERENCE TO THE RPTR'S RECEIVING A PHANTOM ATC CLRNC. THE MGR WAS AWARE OF THE INCIDENTS. HE INFORMED ME THAT THEY (PLTS) WERE GETTING A PHANTOM ATC CLRNC ABOUT ONCE A MONTH. HE STATED THAT THE CTLRS COULD NOT HEAR THE CLRNC TO THE PLTS. CTLRS AND SUPVRS HAVE BEEN BRIEFED AND THEY ARE WATCHING FOR ABNORMAL TURNS BY THE FLCS. THE FBI/FCC ARE TRYING TO TRACK THE SOURCE OF THE PHANTOM CLRNCS. GREAT LAKES REGION HAS PURCHASED A D/F VAN TO LOCATE THE PERSON MAKING THE PHANTOM ATC CLRNCS. EVERY EFFORT IS BEING MADE TO ELIMINATE SOURCE.

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.