Small Aircraft; High Wing; 1 Eng; Fixed Gear
Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Flight Instructor
Flight Crew Last 90 Days 142; Flight Crew Total 687; Flight Crew Type 660
Communication Breakdown; Situational Awareness
Conflict NMAC; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Took Evasive Action
Aircraft; Environment - Non Weather Related; Human Factors
It was a busy day in the pattern at LMO and BJC was closed for pattern work. I had already done one lap in the pattern at LMO and was in the downwind for another lap. In the downwind; the skydiving operation announced a few times; 'Jumpers away'. I saw them and told my student to make a slightly wider pattern to accommodate them. Just as we made a slight deviation; an aircraft; Aircraft Y; entered the pattern mid field downwind and my ADS-B indicated they were the same altitude as us. Aircraft Y announced they had 'downwind traffic in sight' but it was likely another plane. They cut us off not only in the downwind; but also headed straight for the jump zone. The jump plane announced frantically 'parachutes have been deployed'. I was careful not to climb or descend while I did not have Aircraft Y in sight because ADS-B indicated they were same altitudes. We did not see them until they were passing just under us. Once I saw them; I asked their intentions with no response. I decided it was best to depart the airport back to BJC. Upon returning to BJC; I spoke with many instructors from different flight schools in the area and it seems like the traffic pattern at LMO has become increasingly dangerous. Many instructors have had near misses with other pilots not making calls or entering the pattern however they wish.
Pilot reported a NMAC with an aircraft that cut off reporter's aircraft while on the downwind.  This happened LMO airport which is reportedly known for parachuting and had jumpers in the air at the time.