C182 pilot has transmitter failure, squawks 7500 instead of 7600.

Attributes
ACN	305753
Time
Date	199504
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : 177
State Reference	OH
Altitude	msl bound lower : 3000 msl bound upper : 3000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : cvg
Operator	general aviation : personal
Make Model Name	Skylane 182/RG Turbo Skylane/RG
Operating Under FAR Part	Part 91
Flight Phase	climbout : intermediate altitude cruise other other
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : commercial pilot : instrument
Experience	flight time last 90 days : 13 flight time total : 394 flight time type : 30
ASRS Report	305753
Person 2
Affiliation	government : faa
Function	controller : departure
Qualification	controller : radar
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	other
Consequence	faa : reviewed incident with flight crew Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation other

Narrative:

I departed I77 (blue ash) on an IFR flight plan to agc. At the time of departure, the WX was VFR. The forecast for I77 and the route of flight was forecast for IFR in anticipation of frontal passage and anticipated rain with possible thunderstorms. The clearance was received 'as filed' (depart I77/moaks intersection/V5/ape/V12/agc) with instructions 'climb to 3000 ft expect 5000 ft after departure. Squawk XXXX departure frequency 121.0.' departure from I77 occurred at approximately XA16. Static and a lack of radio 'traffic' after departure led to an attempt to raise departure and confirm that we were still in communication. This was to no avail. I made the switch to the #2 radio and immediately heard departure trying to contact us. I tried to transmit back on the #2 radio, but a repeat request from departure indicated that they were not receiving us. Shortly after my attempt to communicate, departure transmitted the request that if I were receiving them to 'identify.' I complied. Departure's response was that they 'guessed' that would continue to communicate with me in this fashion throughout the flight. Several attempts were made to transmit over both radios to see if we could rectify the problem and continue the flight. This did not work. Both transmitters were inoperative. Given that we were only a short distance into the flight, I decided that the safest and logical option for us was to return to our point of origin for repairs. To alert departure to my intentions, I turned to the transponder to squawk the 'radio failure' code prior to initiating the heading change from V5 back to blue ash. Instead of 7600, I mistakenly selected 7500. After approximately 3 mins following the turn toward blue ash, departure asked if this was what I wanted to squawk to 'identify.' I complied. I was then told by departure to maintain 3000 ft. All communications from ATC from here on out ceased. The improper identify code was not realized until I was approached by police officers after engine shutdown. I then phoned ATC to explain to them what had happened.

Original NASA ASRS Text

Title: C182 PLT HAS XMITTER FAILURE, SQUAWKS 7500 INSTEAD OF 7600.

Narrative: I DEPARTED I77 (BLUE ASH) ON AN IFR FLT PLAN TO AGC. AT THE TIME OF DEP, THE WX WAS VFR. THE FORECAST FOR I77 AND THE RTE OF FLT WAS FORECAST FOR IFR IN ANTICIPATION OF FRONTAL PASSAGE AND ANTICIPATED RAIN WITH POSSIBLE TSTMS. THE CLRNC WAS RECEIVED 'AS FILED' (DEPART I77/MOAKS INTXN/V5/APE/V12/AGC) WITH INSTRUCTIONS 'CLB TO 3000 FT EXPECT 5000 FT AFTER DEP. SQUAWK XXXX DEP FREQ 121.0.' DEP FROM I77 OCCURRED AT APPROX XA16. STATIC AND A LACK OF RADIO 'TFC' AFTER DEP LED TO AN ATTEMPT TO RAISE DEP AND CONFIRM THAT WE WERE STILL IN COM. THIS WAS TO NO AVAIL. I MADE THE SWITCH TO THE #2 RADIO AND IMMEDIATELY HEARD DEP TRYING TO CONTACT US. I TRIED TO XMIT BACK ON THE #2 RADIO, BUT A REPEAT REQUEST FROM DEP INDICATED THAT THEY WERE NOT RECEIVING US. SHORTLY AFTER MY ATTEMPT TO COMMUNICATE, DEP XMITTED THE REQUEST THAT IF I WERE RECEIVING THEM TO 'IDENT.' I COMPLIED. DEP'S RESPONSE WAS THAT THEY 'GUESSED' THAT WOULD CONTINUE TO COMMUNICATE WITH ME IN THIS FASHION THROUGHOUT THE FLT. SEVERAL ATTEMPTS WERE MADE TO XMIT OVER BOTH RADIOS TO SEE IF WE COULD RECTIFY THE PROB AND CONTINUE THE FLT. THIS DID NOT WORK. BOTH XMITTERS WERE INOP. GIVEN THAT WE WERE ONLY A SHORT DISTANCE INTO THE FLT, I DECIDED THAT THE SAFEST AND LOGICAL OPTION FOR US WAS TO RETURN TO OUR POINT OF ORIGIN FOR REPAIRS. TO ALERT DEP TO MY INTENTIONS, I TURNED TO THE XPONDER TO SQUAWK THE 'RADIO FAILURE' CODE PRIOR TO INITIATING THE HDG CHANGE FROM V5 BACK TO BLUE ASH. INSTEAD OF 7600, I MISTAKENLY SELECTED 7500. AFTER APPROX 3 MINS FOLLOWING THE TURN TOWARD BLUE ASH, DEP ASKED IF THIS WAS WHAT I WANTED TO SQUAWK TO 'IDENT.' I COMPLIED. I WAS THEN TOLD BY DEP TO MAINTAIN 3000 FT. ALL COMS FROM ATC FROM HERE ON OUT CEASED. THE IMPROPER IDENT CODE WAS NOT REALIZED UNTIL I WAS APCHED BY POLICE OFFICERS AFTER ENG SHUTDOWN. I THEN PHONED ATC TO EXPLAIN TO THEM WHAT HAD HAPPENED.

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.