Flight Crew Flight Instructor; Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Commercial
Flight Crew Last 90 Days 160; Flight Crew Total 450; Flight Crew Type 200
Communication Breakdown
Aircraft Equipment Problem Less Severe
Air Traffic Control Provided Assistance; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Landed As Precaution
Human Factors; Aircraft
On a training flight with a student; we had alternator failure an hour into our lesson. I did not notice the ammeter reading negative until the transponder began to flicker on and off. When I was troubleshooting; I asked the student to look at the ammeter; since it was on his side; and he told me that it was showing a negative reading; and that there was a red light. I immediately turned towards ZZZ1 and began to reduce the electrical load; hoping to lengthen the amount of time that we would have a working radio. At this point I checked into our traffic avoidance system; and noticed that there was heavy traffic at my airport of intended landing. I queued up Approach and told them the nature of my situation. I told them I wasn't sure if I would have enough battery to safely make calls to get into the traffic pattern; considering my transponder was dying. A few minutes later; right after they transferred us to Tower; who quickly cleared us to land; we lost all ability to communicate. We were unable to use our electric flaps on the landing. I taxied back to the ramp and gave Tower a call to see if I needed to fill out any paperwork; and they told me that they had taken care of it. In retrospect; I should have caught the failed alternator sooner. My student had noticed the light; but did not know what it meant; and his yoke was in the way for me to notice it. During our cruise checklist; that is one of the items that we check; and I did not notice anything wrong when we did the checklist 20 minutes prior. Additionally; after noticing the issue I could have just completely turned off the master switch and used pilotage to get us close to [the airport]; after which I could have turned the master back on and then used my radio. I had never had this happen before; so I was trying to make quick; confident decisions.
C172 Instructor Pilot reported returning to departure airport after experiencing alternator failure.