Flight Instructor reported NMAC with aircraft in the traffic pattern of JZP airport.
Synopsis
Flight Instructor reported NMAC with aircraft in the traffic pattern of JZP airport.
Narrative
My student was working in the traffic pattern and practicing landings; using Runway 34 in a northerly wind. As we were at midfield of the downwind leg; the other pilot announced a six-mile final from an IFR waypoint I did not know. I made a radio call announcing that we were on the left downwind leg and asking the Aircraft X their ETA; but received no response. We began looking for the traffic as we proceeded on the downwind leg and went through the standard landing configuration procedures. We still had no visual contact nor further radio contact as we turned and my student announced 'left base Runway 34'. At that point the other pilot announced; emphasizing that they were a jet; which they were on final. I replied thanking the pilot for the confirmation and reporting that we had been looking for the traffic since the mid-field point and still did not see them. Aircraft X replied that they were on short final and wanted to know if we were going to break off or if they needed to. I looked at my student and saw that full power was already applied and was executing a go-around to the upwind leg. I replied that we would divert to the left upwind leg and give them the runway. The Aircraft X pilot called that we 'need to climb'; but I refrained from replying that we were a piston single already at full power. As we crossed the center line at approximately 700 ft. AGL I saw the jet at our right rear quarter and disappearing behind us.Had the jet pilot made their first call at a more reasonable 15 or even 10 miles; we would have had time to evaluate the aircraft speed and ETA purely from their subsequent radio calls. Had they been monitoring their ADS-B In returns; presuming that equipment is installed; Aircraft X would have seen us doing pattern work even if they did not yet have visual contact. Had they replied to our request for their ETA; we could have planned to extend our downwind leg and land after the Aircraft X. And; finally; had they not presumed a straight-in final to a non-towered airport with extensive student training; as advertised by NOTAM; they would have been able to better plan an integrated entry into the traffic pattern. Confirmation bias allowed me to persuade myself that I heard a more normal '15-mile' rather than '6-mile' in the pilot's cluttered transmission; which set us up for being in the wrong place at the wrong time. I should have kept calling the other aircraft until we established communications and could positively confirm each other's location or anticipated earlier an event and put us in a better position.
Second reporter narrative
My student was working in the traffic pattern and practicing landings; using Runway 34 in a northerly wind. As we were taking off; the other aircraft made a CTAF call announcing position to the east and intention to enter the left downwind leg for Runway 34. I made a radio call asking the Aircraft Y pilot if they planned to 'go over the top' or enter left downwind directly but received no response. My student announced left crosswind and 'looking for traffic' and then left downwind and 'looking for the Aircraft Y'. As we were drawing even with the north end of the runway I saw the Aircraft Y come across at midfield and turn directly onto the downwind leg right in front of us. It was by my estimate some 300 ft. below traffic pattern altitude; and I imagine the pilot did not look up enough see us. A contributing factor may have been that JZP currently has no AWOS available and so a pilot might have an incorrect altimeter setting; and without sufficient experience to recognize pattern altitude purely visually the pilot might fly above or below the proper elevation. The pilot did not announce that they were crossing over the field but did announce that they were 'turning left downwind'.I made a radio call announcing that we were approaching mid-field of the left downwind leg and had the Aircraft Y in sight cutting us off low; and I asked if the pilot was going to extend their downwind leg or if we needed to work around them. The pilot replied that they would extend and follow us in. The pilot proceeded southward at what I considered a significantly low altitude; reinforcing my belief that they likely had an incorrect altimeter setting. We landed without conflict and then they landed without incident. This is a perfect example of why; despite its being an approved procedure; we strongly recommend against crossing the field at pattern altitude and turning directly onto the downwind leg. This is our fourth [direct and personal] experience being cut off by entering traffic failing to yield right of way; one of which was a near miss; and an illustration of how easy it can be to miss traffic when either aircraft is not at the expected altitude. Awareness of this aircraft via the pilot's radio calls was helpful even though they did not respond to communications which could have prevented the conflict. We were prepared to orbit on the west side of the airport to allow for separation had they not advised us of their intentions; but with communication established and a landing order agreed all were able to ensure traffic separation.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.