NMAC BETWEEN 2 GA-SMA'S AND LOW FLT BY ONE GA-SMA.

Narrative

THE INCIDENT OCCURRED IN 2/88 AT APPROX XXOO LCL TIME AT THE PLATTSMOUTH MUNI ARPT. A STUDENT PLT AND MYSELF; A CFI; WERE PRACTICING TKOFS; PATTERNS AND LNDGS AT PLATTMOUTH. 1 ADDITIONAL ACFT WAS IN THE TFC PATTERN. WE WERE ON A LEFT BASE LEG TO RWY 16; DSNDING TO LAND; AND HAD TRANSMITTED OUR POS. WE WERE ABOUT 2000' MSL; 800' AGL; WHEN AN SMA Y STARTLED MY STUDENT. WHEN I SPOTTED THE SMA Y IT WAS JUST OFF OF OUR NOSE AND QUICKLY PASSED FROM RIGHT TO LEFT. THE SMA Y WAS VISIBLE THROUGH THE LOWER LEFT PORTION OF THE WINDSCREEN AND WINDOW; NEAR THE LINE BTWN THE PLEXIGLAS AND THE METAL. THE SMA Y PASSED AT APPROX 4 WING LENGTHS DISTANCE; AND WAS HDG APPROX 110. HE APPARENTLY WAS ON A XCOUNTRY FLT. THE SMA Y HDG TO BE WITHIN 500' OF EITHER THE GND; US OR BOTH BASED UPON OUR ALT AND HIS RELATIVE POS TO US. SUCH PROXS MAY BE IN VIOLATION OF FAR'S 91.79 AND 91.65. THE REGISTRATION NUMBER WAS XXXX. CONTINUING WITH THE INCIDENT; I EXECUTED A CLBING RIGHT HAND TURN TO AVOID ANY COLLISION HAZARDS. I ROLLED OUT TO WITNESS THE SMA Y GND TRACK AND REGISTRATION NUMBER. I WAS WELL OUTSIDE OF 10 WING LENGTHS DURING THE WITNESSING. MY OPINION IS THAT A SAFETY MINDED PLT SHOULD NOT FLY NEAR ARPTS AT OR BELOW THE RECOMMENDED TFC PATTERN ALT OF 1000'. THE PLT EXERCISED POOR JUDGEMENT AND NEARLY CREATED AN ACCIDENT BY FLYING WITHIN THE PLATTSMOUTH TFC PATTERN. UNFORTUNATELY; FAR'S DO NOT PROHIBIT SUCH CONDUCT AT UNCTLED ARPTS; SUCH AS PLATTSMOUTH MUNI. MAYBE SOME SORT OF AN ARPT TFC AREA SHOULD BE ESTABLISHED BY UNCTLED ARPTS.