C172 Pilot reported on base another C172 appeared in conflict requiring both aircraft taking evasive action which resulted in a NMAC. C172 Pilot reported transmitting on incorrect frequency.
Synopsis
C172 Pilot reported on base another C172 appeared in conflict requiring both aircraft taking evasive action which resulted in a NMAC. C172 Pilot reported transmitting on incorrect frequency.
Narrative
I was flying circuits in the pattern for ZZZ Runway XX. It was my third circuit. Conditions were clear with unlimited visibility; with moderate turbulence near the ground. I was flying a Cessna 172; which was a new airframe to me. I completed my previous touch and go from ZZZ Runway XX as normal. I made my call for left crosswind; then left downwind. I reached TPA of 5700 ft. in the midfield left downwind. I was not hearing any other aircraft making radio calls (on ZZZ CTAF XXX.X); and I did not see any other aircraft on either my ADS-B in receiver or my iPad. To my knowledge I was the only aircraft in the pattern. I reached a beam the touchdown zone and began to configure for landing. I then made a left turn for the base leg and made an accompanying call. I then looked inside the aircraft to put down the second notch of flaps (20°) as this aircraft required that I hold the flap switch and release it when it was at 20 degrees; instead of 'set and forget' like all the other aircraft I've flown. When I looked back outside; the other aircraft (another C172) was almost directly in front of me; on final for Runway XX; coming from my right at approximately the same altitude. I was startled and momentarily continued straight. The aircraft in front of my then turned sharply to its right; away from me. Seeing it was turning to its right; I then turned to my left; onto a final approach course; as that direction would then give us the most separation. I estimate that the closest we came was approximately 200-300 ft. Although the aircraft and my iPad were both configured to deliver traffic alerts; I never received a traffic alert. I then made a call on CTAF XXX.X that I was turning final and that another aircraft had just crossed directly in front of me. That aircraft then came over the radio and stated that they had accidentally been making their radio calls on Guard and had not seen or heard me until I turned my base. I acknowledged this call and continued my approach; performing a touch and go without further incident. The other aircraft circled back to the right and made an uneventful approach; and terminated their flight. While it is true that the other aircraft was not making proper radio calls; this was in class E airspace and they were not required to make those calls. I had two sources of ADSB-in and did not see them; although I am confident that they had ADSB-out. This may have been because I was zoomed too far in on my ADS-B displays and did not have the opportunity to see them until they were very close. I also did not see them at all on the downwind or initial base turn. My attention was initially focused outside the plane; looking at the runway to make sure that I was lining the turn up properly. Then; once established on base; I was focused inside the plane making sure my speed was correct and that I was selecting the correct flaps. I was very focused on the flaps because if I just left the flap switch on; it would go through 20 degrees all the way to full flaps; which I did not want. I needed to watch the indicator and turn it off when it reached 20 degrees. At no point did I loom to my right; to the final approach course; before turning base or while on base until I saw the other aircraft suddenly 'appear' in front of me. I had erroneously assumed that all relevant traffic would be making radio calls. This is not the case; as this airspace did not require it. The other aircraft; regardless of the fact that they were on the wrong frequency; was not required to have ADS-B nor were they required to be making those calls. I failed to clear the final approach course before turning base; and focusing inside the cockpit and on the runway distracted me from basic see-and-avoid principles at this uncontrolled field. I do not think that fatigue played a part in this incident; although being my third circuit I was possibly complacent; assuming that the same traffic-free conditions would persist through my subsequent circuits. This opportunity reminds me to be much more aware in the traffic pattern. I plan to review AC 90-48 as well as AC 90-66 to expand my tools etc for collision avoidance in the traffic pattern. Before making any turn; I plan to look both ways and not to assume that any traffic is clear of me or aware of me. I am also more acutely aware of the startle effect and how it can inhibit my own reaction time in a situation like this. I am also much more aware of the dangers of in-cockpit distractions; especially in high-workload environments such as the pattern.
Second reporter narrative
On Day 0 I flew the long solo cross-country requirement of private pilot training in a C172. While in the traffic pattern to land at the second airport; uncontrolled class E ZZZ; my airplane came close to another C172 in the base to final turn of Runway XX. I was arriving from the South at 6500 MSL and made position reports at 15; 10; and 5 miles away on CTAF using COM1 while monitoring Guard on COM2. I reported that I would be entering at midfield for left downwind of Runway XX. The only other aircraft in the pattern at ZZZ was another C172. I heard the radio calls of that pilot; as well as radio calls of pilots at nearby ZZZ1; which shares the same CTAF frequency. When I turned onto the downwind I visually observed the other airplane on the left crosswind of Runway XX and heard the pilot's position call on CTAF. Upon reaching abeam the XX numbers I began a normal landing descent process. At this time everything appeared normal and proper as both airplanes in the pattern were making position reports and I could also see the other airplane behind me via Foreflight and I assumed that pilot heard me and saw me visually and most likely on ADS-B as well and would not by a traffic factor. However; as I made the radio call that I was turning base for Runway XX I quickly learned that something was wrong as another pilot stated they were hearing those calls on guard. Confused and concerned; I continued the base leg while verifying the radio was on the proper frequency; which it was so I concluded I was indeed on the proper frequencies and that other pilot was incorrect or possibly hearing traffic elsewhere that I could not. As I was about to make the radio call and enter the base to final turn I observed the audio panel was incorrectly on 'COM2 MIC' and I was in fact not broadcasting on CTAF and the other airplane in the pattern might not be aware of my presence. I quickly pressed 'COM1 MIC' and made my call; and glanced at Foreflight and noticed the other airplane had turned base inside of my path and was about 300 ft. higher with their base leg already about halfway complete. At that same time the other airplane announced they just saw me in front of them and assumed I had entered the pattern on a straight in to final cutting them off. To reduce the risk of a collision I discontinued my left turn and exited the final approach leg to the right; made a radio call to that effect; and began a climbing right turn. The other airplane continued the approach and conducted a touch and go while I circled to the right then landed uneventfully. Lessons learned. As part of verifying that a given radio is set to the proper frequency it is equally important to check that the audio panel is properly set to transmit on COM1. Additionally; it is critical to not assume that traffic behind you has you in sight and will not fly faster decreasing separation in the pattern and to not initiate their turn in front yours thereby cutting in front of you. It is important to not assume other traffic will fly as you expect them to fly. In the future when entering a non-towered traffic pattern or when a new airplane joins a pattern that I'm already in behind me; I'll make radio calls asking if they have me in sight. This; however; will not account for any traffic that is not using ADS-B Out or is without radios and diligence must always be heightened at uncontrolled fields. Finally; remember to aviate before communicating. While it was important to figure out the radio setting issues it was more important to stay focused on flying the airplane; especially at low altitude in the traffic pattern. As a solo student pilot that distraction at that stage of flight had the ability to result in getting slow resulting in a stall in the pattern. The following day I debriefed this situation with my CFI. We discussed the above lessons learned.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.