Flight Crew Commercial; Flight Crew Flight Instructor; Flight Crew Instrument
Flight Crew Last 90 Days 35; Flight Crew Total 1900; Flight Crew Type 600
Communication Breakdown; Confusion; Distraction
Conflict NMAC; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural FAR; Inflight Event / Encounter Other / Unknown
Flight Crew Took Evasive Action
Equipment / Tooling; Human Factors; Procedure; Chart Or Publication
Aircraft X flying a primary student training mission at the non-towered field MQJ. The entire flight took place in the RWY 25 pattern and we had completed 3 TOL's [Take Off and Landings]. On the 4th approach; we were on short final at approximately 400' AGL and 1/4 to 1/2 NM from the threshold on what I would characterize as a stable approach. A second aircraft that I believe was Aircraft Y intercepted the final approach at a 45 degree angle from our left and approximately 200' below us (200' AGL). The second aircraft made no radio calls on the CTAF. I took the controls from the student and made a sharp turn to the right (away from the 2nd aircraft) and a slight climb. I called the 2nd aircraft on CTAF but received no response. We climbed away from the pattern; returned and made an uneventful landing. The student was bothered by the incident enough that we called it a day for training.A second trainer aircraft turning downwind to base and a Bonanza waiting to depart on 25 witnessed the encounter. Both commented on the CTAF about the near miss.Someone at the FBO asked the pilot of the 2nd aircraft about the encounter and he showed them his ForeFlight Sectional map that indicated the CTAF frequency was 122.70. His Sectional was current. (I verified his statement on my copy of ForeFlight). He indicated he made appropriate radio calls on that frequency. The MQJ CTAF frequency was changed from 122.70 to 122.97 approximately three months ago and was reasonably well publicized. Transition to the new frequency has been mostly trouble free. The fact that the old frequency was still shown on a very popular electronic source is troubling.I would strongly suggest that frequency changes be coordinated with Sectional updates. In this case; a transient pilot would have no way of knowing about the frequency change without looking up old; canceled NOTAM's. I would also suggest that a voice recording be added to the end of the AWOS transmission noting a frequency change. This should be left in place for several months.
Small aircraft instructor reported a NMAC on final due to the second aircraft not having the correct frequency for CTAF. The second pilot was using a sectional chart that displayed the incorrect frequency.