INSTRUCTOR PLT OF A PA38 TOOK OVER THE CTLS FROM THE TRAINEE WHEN ANOTHER ACFT WAS OBSERVED MAKING A MISSED APCH FROM THE OPPOSITE END (OR DEP END) OF THE RWY ON WHICH THEY WERE ABOUT TO CROSS. NMAC.

Narrative

AFTER CONDUCTING A TOUCH-AND-GO ON RWY 29 WITH MY STUDENT FLYING THE ACFT (A PA38-112); WE WERE INSTRUCTED TO REMAIN IN L TFC. WHILE ON DOWNWIND; WE WERE CLRED FOR THE 'OPTION' ON RWY 29. WE CONDUCTED A NORMAL TOUCH-AND-GO. WHILE ON DEP I HEARD THE TWR INSTRUCT MTR (A C26); WHICH HAD BEEN CONDUCTING PRACTICE INST APCHS TO THE ARPT; TO TAKE IMMEDIATE EVASIVE ACTION TO AVOID ANOTHER ACFT. BELIEVING THAT ACFT TO BE US; AND SINCE MTR PREVIOUS APCH HAD BEEN TO RWY 29; I FIRST LOOKED BEHIND US. NOT SEEING HIM; I LOOKED FORWARD AGAIN AND OBSERVED MTR INITIATING A GAR FROM THE APCH END OF RWY 17. I TOOK OVER CTL OF THE ACFT AND TOOK IMMEDIATE EVASIVE ACTION (A R TURN TO PASS BEHIND THE C26). ALTHOUGH I PRACTICE THOROUGH COLLISION AVOIDANCE TECHNIQUES; THIS INCIDENT INDICATES TO ME THAT THERE'S ALWAYS ROOM FOR IMPROVEMENT! ADDITIONALLY; AS A SATCS; THIS INDICATES TO ME THE IMPORTANCE OF MAINTAINING A THOROUGH SCAN OF THE PATTERN AREA; EVEN DURING PERIODS OF SLOW TFC. FINALLY; IT APPEARED TO ME THAT THE C26 PLT(S) WERE PREOCCUPIED WITH THE INST APCH PROC. I DID NOT HEAR THEM RPT DORSY (THE FAF) AND I BELIEVE THEY WERE NOT CLRED TO USE RWY 17.