INSTRUCTOR PLT WITH PLT DOING REAR SEAT TRAINING IN AN AERONCA HAS LOSS OF ENG PWR. USING CARB HEAT HE IS ABLE TO CORRECT THE PROB WHILE TURNING TO REMAIN IN PATTERN AND NEAR THE ARPT. HE OVERFLIES A RADIO CTLED ACFT OP AT LOW ALT.

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MY WIFE AND I WERE DEPARTING FROM 1K3; DERBY; KS; IN AN AERONCA 7DC CHAMP. AFTER WARMING UP THE ENG AND DOING THE STANDARD RUN-UP; INCLUDING A CHK OF THE MAGNETOS AND CARB HEAT; WE TOOK OFF TO THE S. MY WIFE WAS OCCUPYING THE REAR SEAT; AND WAS AT THE CTLS DURING THE INITIAL TKOF. SHE IS A PVT PLT; CURRENT AND QUALIFIED IN THE ACFT. THE PURPOSE OF THE FLT WAS TO BEGIN TRAINING HER IN TKOFS AND LNDGS FROM THE REAR SEAT. SHORTLY AFTER BREAKING GND THE ENG BEGAN TO LOSE PWR; BY 150 RPM OR SO; WITH FLUCTUATIONS. I TOOK THE CTLS WITH THE STANDARD 'I HAVE THE AIRPLANE' VERBAL HDOF. I DID THIS BECAUSE; AS THE INSTRUCTOR AND FRONT SEAT OCCUPANT; I HAD BETTER FORWARD VISIBILITY AND WAS THUS IN A BETTER POS TO MAKE AN EMER LNDG; SHOULD IT BECOME NECESSARY. I APPLIED FULL CARB HEAT; WHICH RESULTED IN FURTHER FLUCTUATIONS IN PWR. I LEFT IT IN FULL-HOT; HOWEVER; RECALLING THAT IT USUALLY TAKES TIME FOR CARB HEAT TO CLR AN ICE BUILD-UP. WITH THE TACH HOVERING AROUND 2100-2200 RPM AT FULL THROTTLE; I STILL HAD ENOUGH PWR TO STAY AIRBORNE; ALTHOUGH THE CLB RATE WAS SLOW. AFTER CLBING TO APPROX 200-300 FT; I MADE AN EARLY XWIND TURN TO REMAIN IN A TIGHT L-HAND PATTERN; WHICH I KNEW WOULD KEEP THE AIRPLANE POINTED IN THE DIRECTION OF THE CLEAREST; LEAST-POPULATED AREAS IN THE VICINITY OF THE ARPT; AND WHICH WOULD GIVE ME THE OPTION TO MAKE A XFIELD LNDG TO THE NW; SHOULD THAT BECOME NECESSARY. I CONTINUED THE CLB AND MADE A TURN TO DOWNWIND APPROX 1/4 MI SE OF THE RWY. BY THE TIME I WAS ABEAM THE APCH END ON DOWNWIND THE PROB BEGAN TO CLR. I CLOSED THE CARB HEAT AND GOT BACK FULL PWR. I MADE A FULL; CLBING CIRCLE OVER THE ARPT; ALTERNATELY OPENING AND CLOSING THE CARB HEAT VALVE. SATISFIED THAT THE PROB WAS INDEED CARB ICE; AND THAT IT WAS RESOLVED; WE CONTINUED OUR FLT TO OUR PRACTICE AREA SE OF THE ARPT. ONLY LATER DID I REALIZE THAT MY XWIND TURN MAY HAVE TAKEN ME OVER; OR NEAR; A MODEL AIRPLANE OPS AREA; IN USE AT THE TIME; AT AN ALT OF LESS THAN 500 FT. THEIR FLAG WAS UP (DUE TO THEIR PROX TO THE ARPT; THEY RAISE A RED FLAG WHENEVER THEIR AREA IS IN USE); BUT I DIDN'T SEE IT. BY THE TIME I WAS IN POS TO SEE IT; I WAS ALREADY DEEPLY INVOLVED IN MY OWN SIT. IT SOUNDS SO SELF-SERVING; SO CONVENIENT; TO RELY ON EMER AUTH TO SAY 'I HAD CARB ICE UNTIL I WAS ON DOWNWIND' AS A WAY TO EXPLAIN AWAY A VIOLATION OF ALT RESTRS. I'VE READ NTSB CASES WHERE PEOPLE ATTEMPTED TO USE THAT EXCUSE; TO NO AVAIL. BUT WHAT IF IT'S REALLY TRUE? WHAT IF THAT REALLY DID HAPPEN; AS IT DID IN MY CASE? SHOULD I HAVE LANDED? THE PROB WAS OVER BY THE TIME I WAS IN POS FOR A NORMAL LNDG. I EVEN CIRCLED TO MAKE SURE BEFORE GOING ON. SHOULD I HAVE POINTED THE AIRPLANE IN SOME OTHER DIRECTION? EVERY MOVE I MADE PUT ME IN A BETTER POS TO AVOID HARM AND MINIMIZE DAMAGE SHOULD THE ENG FAIL OUTRIGHT. EVEN IF I HAD KNOWN THAT THE MODEL AIRPLANE FIELD WAS IN USE; I MIGHT HAVE DONE THE SAME THING. LNDG OVER THEM INTO THE HARD; FLAT FIELD BEYOND THEM WOULD HAVE BEEN PREFERABLE TO GOING DOWN INTO TREES; HOUSES; OR A SOGGY; PLOWED FARM FIELD (DIRECTLY AHEAD); A HEAVILY WOODED AREA WITH A PWR LINE RUNNING THROUGH IT; A SCHOOL YARD; OR DENSELY POPULATED AREA (TO THE R) OR DOING A 180 DEG AT LOW ALT. I'M NOT SURE WHAT I WOULD HAVE DONE DIFFERENTLY; A LONGER RUN-UP; MAYBE; WITH THE CARB HEAT ON UNTIL FULL PWR IS APPLIED. AND I HAVE TO ADMIT; I WOULD PROBABLY GO AHEAD AND LAND; NOT BECAUSE IT'S SAFER; AFTER ALL; THE PROB HAD CLRED (AND THERE WERE POSITIVELY NO OTHER INDICATIONS); BUT BECAUSE IT WOULD ADD TO MY CREDIBILITY BEFORE AN ADMINISTRATIVE LAW JUDGE. PARANOIA. NOW; THAT'S A HELL OF A THING TO THINK ABOUT DURING AN EMER; AND A HELL OF A THING TO HAVE TO ADMIT.