SMA PERFORMS A MISSED APCH AND EVASIVE ACTION DIVE TURN TO AVOID WAKE TURB ENCOUNTER WITH ACR MLG WHO JUST EXPERIENCED A HDG TRACK DEV IN FRONT AND ABOVE HIM DURING AN OVERSHOOT APCH TO WRONG RWY.

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PRACTICE NDB APCH TO 16R AT SACRAMENTO METROPOLITAN; SACRAMENTO; CA; ON R BASE AT 1800 FT WHEN AIR CARRIER CALLED 5 MI OUT AT 5000 FT ON L BASE FOR APCH. TWR/APCH (I'M NOT SURE IF WE'D BEEN HANDED OFF TO TWR YET; DON'T THINK SO) RPTED US TO EACH OTHER AND WE BOTH RPTED OTHER IN SIGHT. AIR CARRIER HAD ARPT IN SIGHT AND WAS CLRED FOR VISUAL TO 16L. APCH ASKED CARRIER IF HE WAS TOO HIGH TO MAKE RWY FROM HIS POS; CARRIER SAID NO; WAS OK. AS WE TURNED FINAL ON APCH FOR 16R CARRIER DISAPPEARED ABOVE AND BEHIND US. WE SWITCHED TO TWR AND RPTED ON APCH. I LEANED FORWARD AND LOOKED UP AND AS FAR BACK AS I COULD THROUGH THE TOP OF THE WINDSHIELD OF OUR SMA TO SPOT AIR CARRIER; EXPECTED HIM OFF TO L LINED UP FOR 16L. HE APPEARED DIRECTLY ABOVE US; DSNDING RAPIDLY DIRECTLY IN FRONT OF US (ESTIMATED 1500 FT) FOR 16R (OUR RWY!) TWR CALLED HIM AT THIS TIME -- NO RESPONSE. I TOOK THE ACFT (STUDENT UNDER HOOD) AND DSNDED RAPIDLY TO 600 FT IN A R TURN TO AVOID WAKE TURB FROM ACR. ABOUT THIS TIME HE TURNED L FOR 16L AND LANDED. I TOLD TWR WE WERE GOING TO STAY TO THE W OF THE FIELD ON OUR MISSED APCH. NO COMMENT FROM AIR CARRIER OR TWR ON SITUATION. I BELIEVE THE AIR CARRIER LOST US IN THEIR DSCNT AND LINED UP N WRONG RWY DUE TO RUSH OF DSCNT. GLAD I WAS WATCHING OUT FOR HIM! YOU'RE NEVER TOO EXPERIENCED TO MAKE MISTAKES.