Narrative:

I work at cmh approach control. A local avionics facility frequently calls our TRACON to advise he will be doing mode C checks on xponders. These mode C checks cause TCASII alerts to arrs at our airport. This shop frequently checks mode C readouts up to FL290. This shop expects us to notify everyone above us about these mode C checks. These events increase our workload and have caused RA's in the past. Is there not some kind of electronic shield that these avionics shops use to test mode C readouts? Is this shop supposed to have one? Callback conversation with reporter revealed the following information: reporter stated this mode C testing interference doesn't happen all of the time. Reporter claimed there is another avionics facility located on the airport that does similar testing and approach control has not received testing interference from this shop. Reporter wanted to know if there was anything that could be done to eliminate this interference. Analyst asked if reporter had contacted anybody locally. Reporter indicated that no contacts have been made. Analyst suggested that employee coordinate the problem through facility management, airways facilities, flight standards and/or FCC district office(south).

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Original NASA ASRS Text

Title: RPTR COMPLAINED THAT WHEN A LCL AVIONICS SHOP LOCATED ON THE CMH ARPT PERFORMS THEIR MODE C XPONDER CHKS, IT CAUSES FALSE TCASII ALERTS, THIS AVIONICS SHOP ALSO CALLS THE FACILITY AND WANTS THEM TO COORDINATE THESE EVENTS WITH ALL CONCERNED PARTIES, WHICH INCREASES THE FACILITY WORKLOAD.

Narrative: I WORK AT CMH APCH CTL. A LCL AVIONICS FAC FREQUENTLY CALLS OUR TRACON TO ADVISE HE WILL BE DOING MODE C CHKS ON XPONDERS. THESE MODE C CHKS CAUSE TCASII ALERTS TO ARRS AT OUR ARPT. THIS SHOP FREQUENTLY CHKS MODE C READOUTS UP TO FL290. THIS SHOP EXPECTS US TO NOTIFY EVERYONE ABOVE US ABOUT THESE MODE C CHKS. THESE EVENTS INCREASE OUR WORKLOAD AND HAVE CAUSED RA'S IN THE PAST. IS THERE NOT SOME KIND OF ELECTRONIC SHIELD THAT THESE AVIONICS SHOPS USE TO TEST MODE C READOUTS? IS THIS SHOP SUPPOSED TO HAVE ONE? CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THIS MODE C TESTING INTERFERENCE DOESN'T HAPPEN ALL OF THE TIME. RPTR CLAIMED THERE IS ANOTHER AVIONICS FACILITY LOCATED ON THE ARPT THAT DOES SIMILAR TESTING AND APCH CTL HAS NOT RECEIVED TESTING INTERFERENCE FROM THIS SHOP. RPTR WANTED TO KNOW IF THERE WAS ANYTHING THAT COULD BE DONE TO ELIMINATE THIS INTERFERENCE. ANALYST ASKED IF RPTR HAD CONTACTED ANYBODY LOCALLY. RPTR INDICATED THAT NO CONTACTS HAVE BEEN MADE. ANALYST SUGGESTED THAT EMPLOYEE COORDINATE THE PROB THROUGH FACILITY MGMNT, AIRWAYS FACILITIES, FLT STANDARDS AND/OR FCC DISTRICT OFFICE(S).

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.