Flight Lesson: Radio silence

I was a student pilot with 30 hours in a Cessna 172. I had decided to fly to Livermore, California (LVK), from Oakland (OAK), do some air work in the practice area, then perform touch and goes on the shorter runway. The first two patterns went without a hitch, but when turning downwind after the third touch and go, I realized I hadn’t heard radio chatter since my last crosswind. I saw the mic button on the intercom panel and the frequency on the radio stack display blinking, but I had no idea what that meant. I tried to call the tower several times, but all I heard was radio silence.

I re-plugged the headset. The intercom panel and radio stack seemed fine—except that blinking light. I switched to com 2 to try and hear the automatic terminal information service (ATIS). Still nothing. By this time, I was splitting my attention between flying the pattern (already overshot my descent point) and troubleshooting, and I was pretty sure something was wrong with the radio.

I squawked 7600. I knew it would not change a thing in the airplane but putting in an emergency squawk and getting absolutely no response was underwhelming. Abandoning all hope of fixing the radio in the air, I broadcast my intention on the tower frequency to land full stop. I exited onto the taxiway, stopped, and did my after-landing checklist. The radio was still not working, but I dialed in ground frequency anyway, put the tower on com 2, and listened to both. Somehow, I heard radio transmissions, either ground or tower telling me to wiggle my rudder if I could hear the transmission, so I did. I followed the light gun signals and returned to the ramp.

At the fuel pump, I called my instructor, who suggested plugging in the headset to the co-pilot side. It was like magic! Suddenly I heard the chatter, and radio check with ground was great. Maybe it’s just the circuit on my side that’s the issue, I thought. I shut down the airplane and refueled.

The problem seemed to return after I restarted the engine. I could hear the radio being cut off intermittently. I looked at the radio stack when the reception was flickering, and the transmit “T” symbol was flashing on and off. I wiggled the co-pilot side push-to-talk button again. The transmission stopped for three seconds, and then the intermittent transmission started again. I wiggled the button again, but now no matter what I did, the microphone was stuck in the On position.

Turns out I had a hot microphone the whole time. No wonder I couldn’t hear anything. I switched the headset back to the pilot side and hit the intercom system pilot isolation, and everything was working fine. I later learned that the push-to-talk button and headset jacks were newly installed after a recent avionics upgrade, and I was the first one who encountered this problem.

I flew back to Oakland after apologizing to Livermore ground and tower for hogging the channel. I learned that many indications on the panel are subtle, so I need to be extra detailed when troubleshooting. Second, there is nothing shameful about an emergency squawk. And troubleshooting and flying at the same time is hard, and distracted flying is dangerous. Now I understand why the instructor says: “Fly the airplane first.”

Xin “Frank” Qi is a student pilot who lives in Berkeley, California.