Narrative:

I was cruising ssw towards lyh VOR (109.2 MHZ) when DME readout changed from about 65 DME to 9 DME then counted down to about 1 DME when over downtown charlottesville; va. DME counted up to about 9 DME then switched correctly to about 45 DME to lyh VOR. On way back on 47 degree radial; lyh counted up to about 45 DME them switched to 9 DME and counted down to abeam center of center of charlottesville; va. Obviously there is DME interference. Is my rented plane's DME defective or is there a powerful DME transmitter in the center of charlottesville? My guess is some sort of research at university of virginia or some sort of private NAVAID for medevac helicopters at univ of virginia hospital. In either case; I'm glad it was VFR at the time. Azs NDB was a help also. DME signal appeared to be near azs NDB; but not co-located.callback conversation with reporter revealed the following information: reporter stated that during his sbound transit toward lyh VORTAC; the DME read 65 NM and was decreasing. As he approached cho; the DME switched to 9 NM and began to decrease until abeam the city of charlottesville at which time it began to increase until 9 NM. At that time it switched to 45 NM and began to decrease toward lyh VORTAC. On his return trip he indicated that the same event occurred with the 9 NM prior to charlottesville and ending at 9 NM past charlottesville. The reporter indicated that during the first transit south; he thought it was an anomaly with the aircraft; however; upon transiting north; he checked the readings and they indicated the same as the other transit only in reverse. He thought it may be a trasmitter at the hospital or university.

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Original NASA ASRS Text

Title: PA28 PLT HAS ERRONEOUS DME READING WHILE IN CRUISE NEAR CHO AND AZS NDB.

Narrative: I WAS CRUISING SSW TOWARDS LYH VOR (109.2 MHZ) WHEN DME READOUT CHANGED FROM ABOUT 65 DME TO 9 DME THEN COUNTED DOWN TO ABOUT 1 DME WHEN OVER DOWNTOWN CHARLOTTESVILLE; VA. DME COUNTED UP TO ABOUT 9 DME THEN SWITCHED CORRECTLY TO ABOUT 45 DME TO LYH VOR. ON WAY BACK ON 47 DEG RADIAL; LYH COUNTED UP TO ABOUT 45 DME THEM SWITCHED TO 9 DME AND COUNTED DOWN TO ABEAM CTR OF CTR OF CHARLOTTESVILLE; VA. OBVIOUSLY THERE IS DME INTERFERENCE. IS MY RENTED PLANE'S DME DEFECTIVE OR IS THERE A POWERFUL DME TRANSMITTER IN THE CTR OF CHARLOTTESVILLE? MY GUESS IS SOME SORT OF RESEARCH AT UNIVERSITY OF VIRGINIA OR SOME SORT OF PRIVATE NAVAID FOR MEDEVAC HELIS AT UNIV OF VIRGINIA HOSPITAL. IN EITHER CASE; I'M GLAD IT WAS VFR AT THE TIME. AZS NDB WAS A HELP ALSO. DME SIGNAL APPEARED TO BE NEAR AZS NDB; BUT NOT CO-LOCATED.CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT DURING HIS SBOUND TRANSIT TOWARD LYH VORTAC; THE DME READ 65 NM AND WAS DECREASING. AS HE APCHED CHO; THE DME SWITCHED TO 9 NM AND BEGAN TO DECREASE UNTIL ABEAM THE CITY OF CHARLOTTESVILLE AT WHICH TIME IT BEGAN TO INCREASE UNTIL 9 NM. AT THAT TIME IT SWITCHED TO 45 NM AND BEGAN TO DECREASE TOWARD LYH VORTAC. ON HIS RETURN TRIP HE INDICATED THAT THE SAME EVENT OCCURRED WITH THE 9 NM PRIOR TO CHARLOTTESVILLE AND ENDING AT 9 NM PAST CHARLOTTESVILLE. THE RPTR INDICATED THAT DURING THE FIRST TRANSIT S; HE THOUGHT IT WAS AN ANOMALY WITH THE ACFT; HOWEVER; UPON TRANSITING N; HE CHKED THE READINGS AND THEY INDICATED THE SAME AS THE OTHER TRANSIT ONLY IN REVERSE. HE THOUGHT IT MAY BE A TRASMITTER AT THE HOSPITAL OR UNIVERSITY.

Data retrieved from NASA's ASRS site as of January 2009 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.