Small aircraft on IFR flight has radio failure. Squawks 7700, then 7600. Continues to VMC, squawks 1...

Attributes
ACN	201812
Time
Date	199202
Day	Fri
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : sbm
State Reference	WI
Altitude	msl bound lower : 5000 msl bound upper : 5000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zau
Operator	general aviation : instructional
Make Model Name	Small Aircraft, Low Wing, 2 Eng, Retractable Gear
Flight Phase	cruise other descent : approach descent other
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : cfi pilot : commercial pilot : instrument
Experience	flight time last 90 days : 35 flight time total : 350 flight time type : 3
ASRS Report	201812
Person 2
Affiliation	Other
Function	instruction : instructor
Qualification	pilot : cfi
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	other other : unspecified cockpit
Resolutory Action	flight crew : declared emergency none taken : unable
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	Aircraft

Narrative:

En route to sbm from ldm, experienced loss of communications with ATC. After trying to reach ATC via minneapolis and chicago ctrs without success, set squawk code 7700 into transponder for 1 min then 7600 for the next 15 min. Continued to sbm via last route and altitude clearance received. When within MSA sector, initiated descent to 2600 ft (MSA). Broke into VFR conditions at approximately 3200 ft. Upon encountering VFR conditions changed transponder squawk code to 1200, entered left traffic pattern upon arriving at sbm. Contacted FSS (grb) via telephone after landing. ATC reported that they did not receive 1200 transponder squawk code. Reported to them the procedure we used including squawking 1200 upon reaching VFR conditions. ATC explained no report would need to be submitted because we indeed did squawk 1200, they just did not see it on their radar. Possible reason for unseen squawk code was distance from facility and altitude being flown. Transponder was operational, set to mode 'C,' and set to 1200 upon double checking it. Radio failure cause is being checked into.

Original NASA ASRS Text

Title: SMA ON IFR FLT HAS RADIO FAILURE. SQUAWKS 7700, THEN 7600. CONTINUES TO VMC, SQUAWKS 1200.

Narrative: ENRTE TO SBM FROM LDM, EXPERIENCED LOSS OF COMS WITH ATC. AFTER TRYING TO REACH ATC VIA MINNEAPOLIS AND CHICAGO CTRS WITHOUT SUCCESS, SET SQUAWK CODE 7700 INTO TRANSPONDER FOR 1 MIN THEN 7600 FOR THE NEXT 15 MIN. CONTINUED TO SBM VIA LAST RTE AND ALT CLRNC RECEIVED. WHEN WITHIN MSA SECTOR, INITIATED DSCNT TO 2600 FT (MSA). BROKE INTO VFR CONDITIONS AT APPROX 3200 FT. UPON ENCOUNTERING VFR CONDITIONS CHANGED TRANSPONDER SQUAWK CODE TO 1200, ENTERED L TFC PATTERN UPON ARRIVING AT SBM. CONTACTED FSS (GRB) VIA TELEPHONE AFTER LNDG. ATC RPTED THAT THEY DID NOT RECEIVE 1200 TRANSPONDER SQUAWK CODE. RPTED TO THEM THE PROC WE USED INCLUDING SQUAWKING 1200 UPON REACHING VFR CONDITIONS. ATC EXPLAINED NO RPT WOULD NEED TO BE SUBMITTED BECAUSE WE INDEED DID SQUAWK 1200, THEY JUST DID NOT SEE IT ON THEIR RADAR. POSSIBLE REASON FOR UNSEEN SQUAWK CODE WAS DISTANCE FROM FACILITY AND ALT BEING FLOWN. TRANSPONDER WAS OPERATIONAL, SET TO MODE 'C,' AND SET TO 1200 UPON DOUBLE CHKING IT. RADIO FAILURE CAUSE IS BEING CHKED INTO.

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.

Small aircraft on IFR flight has radio failure. Squawks 7700, then 7600. Continues to VMC, squawks 1200.