C152 INSTRUCTOR AND STUDENT HAVE VHF COM RADIO FAILURE. THEY SQUAWK THE APPROPRIATE NO COM XPONDER CODE AND TWR GAVE A GREEN LIGHT FOR LNDG.

Narrative

DEPARTED MSN CLASS C AIRSPACE WITH STUDENT PLT FOR A SATELLITE ARPT OUTSIDE MSN CLASS C AIRSPACE. UPON RETURN FLT; APCHING MSN CLASS C AIRSPACE; DETERMINED THAT 2-WAY RADIO HAD FAILED. SQUAWKED 7600 ON XPONDER; OBSERVED REPLY; AND PROCEEDED TO MSN ARPT. AS WE REACHED VISUAL RANGE WITH THE CTL TWR; OBSERVED GREEN LIGHT GUN SIGNAL FOR LNDG AND LANDED. CALLED TWR CTLR VIA TELEPHONE TO EXPLAIN SIT AND WAS TOLD OF MSN CLASS C AIRSPACE VIOLATION. REFED 2002 FAR-AIM TO CHK IF AIRSPACE VIOLATION WAS CORRECT. AIM 6-4-1 REGARDING LOST COMS INDICATES THAT FAILURE OF 2-WAY RADIOS IN VFR CONDITIONS 'EACH PLT SHALL CONTINUE THE FLT UNDER VFR AND LAND AS SOON AS PRACTICAL.' FAR 91.130 INDICATES THAT ACFT APCHING CLASS C AIRSPACE MUST 'ESTABLISH 2-WAY RADIO COMS WITH THE ATC FACILITY PROVIDING AIR TFC SVCS PRIOR TO ENTERING THAT AIRSPACE AND THEREAFTER MAINTAIN THOSE COMS WHILE WITHIN THAT AIRSPACE.' I UNDERSTAND THAT FAR'S ARE REGULATORY AND THAT THE AIM IS NOT. HOWEVER; I BELIEVE THAT THE AIM SHOULD REFER BACK TO FAR REG 91.130 SINCE IT CONTRADICTS WHAT IS INDICATED IN THE AIM SECTION GIVING GUIDANCE ABOUT 2-WAY RADIO COM FAILURES. BY DEFINITION IT APPEARS AS IF A MODE C XPONDER COULD BE INTERPRETED TO BE A 2-WAY RADIO.