Narrative:

I was in the traffic pattern in a C172 with a student pilot; teaching pattern work. I announced 45 degree entry to right downwind runway xx at ZZZ. When we reached the downwind leg; I announced downwind leg. I was startled to hear from aircraft Y that he too was downwind runway xx. I immediately asked him to state your position. He said he was over the freeway. The freeway is about 3 miles from the runway. I told him that the freeway was not in the pattern.moments later; once abeam the numbers to runway xx; I was startled to see aircraft Y go directly underneath us toward the runway; then make a 360 and join the pattern below us.I asked him: 'aircraft Y; what are you doing?' he said; 'I saw you in the pattern so I decided to go below you.' this is highly unsafe practice. He nearly collided with us. Later; he landed on runway xx while we were still on the runway in our landing roll. Someone should reach out to this pilot and provide remedial training. A FAA report has been filed.

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Original NASA ASRS Text

Title: Flight instructor reported that while on the downwind leg of the traffic pattern; another aircraft flew directly below the instructor's aircraft; performed a 360-degree turn and joined the pattern. That aircraft then proceeded to land on the runway while the instructor was on the landing roll.

Narrative: I was in the traffic pattern in a C172 with a student pilot; teaching pattern work. I announced 45 degree entry to right downwind Runway XX at ZZZ. When we reached the downwind leg; I announced downwind leg. I was startled to hear from Aircraft Y that he too was downwind Runway XX. I immediately asked him to state your position. He said he was over the freeway. The freeway is about 3 miles from the runway. I told him that the freeway was not in the pattern.Moments later; once abeam the numbers to Runway XX; I was startled to see Aircraft Y go directly underneath us toward the runway; then make a 360 and join the pattern below us.I asked him: 'Aircraft Y; what are you doing?' He said; 'I saw you in the pattern so I decided to go below you.' This is highly unsafe practice. He nearly collided with us. Later; he landed on Runway XX while we were still on the runway in our landing roll. Someone should reach out to this pilot and provide remedial training. A FAA report has been filed.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.