Skyhawk 172/Cutlass 172
Flight Crew Commercial; Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Flight Instructor
Flight Crew Last 90 Days 85; Flight Crew Total 661; Flight Crew Type 416
Communication Breakdown; Confusion; Distraction
Conflict NMAC
Flight Crew Took Evasive Action
Human Factors; Procedure
Departing from ZZZ. Initial Climb on runway heading with intention to remain in pattern. Aircraft Y was crossing ZZZ VOR before our takeoff and had announced on CTAF that he was going to cross midfield; make a teardrop entry to the left downwind for the runway. He specifically stated that he was going to enter downwind behind us. When climbing through 600 feet; I received a traffic warning from ADS-B stating that traffic (Aircraft Y) was nearly overhead with 500 feet vertical separation. Upon reaching 800 feet the traffic (Aircraft Y) was directly overhead with 300 feet vertical separation. This event caused us to temporarily suspend the climb until Aircraft Y had passed. Aircraft Y was below pattern altitude; 1;200 feet; by 100 feet when he was closest to us. This aircraft flew nearly the entire teardrop maneuver off the departure end of the runway at pattern altitude and below. Then proceeded to cut across the upwind portion of the pattern to join the downwind from the inside; rather than the intended 45-degree entry.
C172 flight Instructor providing training at a non-towered airport reported an NMAC with an aircraft that did not fly the pattern they stated on CTAF.