Narrative:

After having been given own navigation and altitude to west practice area; climbed to 3500 ft MSL and proceeded to southern portion of practice area due to observed traffic information system (tis) activity in the northern portion. Demonstrated the lean assist function of the G1000 system. Upon completed saw a dark shadow overhead which my student idented as a helicopter; I thought it was a flock of birds. No tis information or warning was received. To verify it was a helicopter; did a quick left 360 degrees and did observe the helicopter traffic eastbound at our altitude. Reported the event and was told there was 'a lifeguard helicopter with no transponder in the area which should pass underneath.' told ATC he passed overhead at around 100 ft (estimated). ATC then stated the helicopter initially called ZZZ1 inbound; which is to the northwest of ZZZ. They said then he called ZZZ2 inbound which is to the southeast of ZZZ and in a direct line with our course. No communications with the helicopter were noted after the incident. It was apparent ATC allowed the inoperative-transponder helicopter in class C airspace prior to having positive radar contact with him. Contributing factors may have been the fact it was a lifeguard call sign and the helicopter pilot may have initially misidented his inbound VFR reporting point upon initial call-up.

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Original NASA ASRS Text

Title: A C172 INSTRUCTOR DEMONSTRATING ADVANCED NAV REPORTS AN NMAC WITH A NON TRANSPONDER EQUIPPED HELICOPTER THAT MISREPORTED ITS POSITION.

Narrative: AFTER HAVING BEEN GIVEN OWN NAV AND ALT TO W PRACTICE AREA; CLBED TO 3500 FT MSL AND PROCEEDED TO SOUTHERN PORTION OF PRACTICE AREA DUE TO OBSERVED TFC INFO SYS (TIS) ACTIVITY IN THE NORTHERN PORTION. DEMONSTRATED THE LEAN ASSIST FUNCTION OF THE G1000 SYS. UPON COMPLETED SAW A DARK SHADOW OVERHEAD WHICH MY STUDENT IDENTED AS A HELI; I THOUGHT IT WAS A FLOCK OF BIRDS. NO TIS INFO OR WARNING WAS RECEIVED. TO VERIFY IT WAS A HELI; DID A QUICK L 360 DEGS AND DID OBSERVE THE HELI TFC EBOUND AT OUR ALT. RPTED THE EVENT AND WAS TOLD THERE WAS 'A LIFEGUARD HELI WITH NO XPONDER IN THE AREA WHICH SHOULD PASS UNDERNEATH.' TOLD ATC HE PASSED OVERHEAD AT AROUND 100 FT (ESTIMATED). ATC THEN STATED THE HELI INITIALLY CALLED ZZZ1 INBOUND; WHICH IS TO THE NW OF ZZZ. THEY SAID THEN HE CALLED ZZZ2 INBOUND WHICH IS TO THE SE OF ZZZ AND IN A DIRECT LINE WITH OUR COURSE. NO COMS WITH THE HELI WERE NOTED AFTER THE INCIDENT. IT WAS APPARENT ATC ALLOWED THE INOP-XPONDER HELI IN CLASS C AIRSPACE PRIOR TO HAVING POSITIVE RADAR CONTACT WITH HIM. CONTRIBUTING FACTORS MAY HAVE BEEN THE FACT IT WAS A LIFEGUARD CALL SIGN AND THE HELI PLT MAY HAVE INITIALLY MISIDENTED HIS INBOUND VFR RPTING POINT UPON INITIAL CALL-UP.

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.