Narrative:

During a night cross country instructional flight of a student pilot, we were xferred from longview departure and directed to contact shv approach in 10 mi. Due to my student having some trouble with his flight log, my attention was focused inside and I lost track of our time as we approached shv class C airspace. When we got around to calling up shv approach, we were probably 1 mi outside their airspace. Our radio failed to pick up anything on their frequency, however, and by the time I realized our situation we were entering the aforementioned airspace. We exited their airspace by descending below the outer shelf. Our radio was confirmed to be broken on the ground, but just on 2 frequencys shv approach 119.9 and GGG ATIS 119.65. Operation on GGG tower frequency of 119.2 was fine. The offending radio was a bendix king KX155 tso. I believe my relatively low level of experience as a flight instructor was part of the cause. Staying ahead of the plane and the student seems to be the key. Also, I didn't know that a digital radio could fail on just 1 or 2 frequencys and learning that fact used up what little time I had given us to establish communication before entering class C airspace.

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Original NASA ASRS Text

Title: AN INSTRUCTOR PLT IN A PA28-161 INADVERTENTLY PENETRATES THE CLASS C OF SHV WHILE GIVING AN STUDENT PLT XCOUNTRY INSTRUCTION ON A NIGHT OP.

Narrative: DURING A NIGHT XCOUNTRY INSTRUCTIONAL FLT OF A STUDENT PLT, WE WERE XFERRED FROM LONGVIEW DEP AND DIRECTED TO CONTACT SHV APCH IN 10 MI. DUE TO MY STUDENT HAVING SOME TROUBLE WITH HIS FLT LOG, MY ATTN WAS FOCUSED INSIDE AND I LOST TRACK OF OUR TIME AS WE APCHED SHV CLASS C AIRSPACE. WHEN WE GOT AROUND TO CALLING UP SHV APCH, WE WERE PROBABLY 1 MI OUTSIDE THEIR AIRSPACE. OUR RADIO FAILED TO PICK UP ANYTHING ON THEIR FREQ, HOWEVER, AND BY THE TIME I REALIZED OUR SIT WE WERE ENTERING THE AFOREMENTIONED AIRSPACE. WE EXITED THEIR AIRSPACE BY DSNDING BELOW THE OUTER SHELF. OUR RADIO WAS CONFIRMED TO BE BROKEN ON THE GND, BUT JUST ON 2 FREQS SHV APCH 119.9 AND GGG ATIS 119.65. OP ON GGG TWR FREQ OF 119.2 WAS FINE. THE OFFENDING RADIO WAS A BENDIX KING KX155 TSO. I BELIEVE MY RELATIVELY LOW LEVEL OF EXPERIENCE AS A FLT INSTRUCTOR WAS PART OF THE CAUSE. STAYING AHEAD OF THE PLANE AND THE STUDENT SEEMS TO BE THE KEY. ALSO, I DIDN'T KNOW THAT A DIGITAL RADIO COULD FAIL ON JUST 1 OR 2 FREQS AND LEARNING THAT FACT USED UP WHAT LITTLE TIME I HAD GIVEN US TO ESTABLISH COM BEFORE ENTERING CLASS C AIRSPACE.

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.