A C310 LNDG ON RWY 35 CONFUSES RWY 35 WITH RWY 32 AND PASSES DIRECTLY OVER B727 HOLDING ON RWY 32 AWAITING CLRNC FOR TKOF. THE B727 FO OBSERVED THE ACFT LINING UP ON THE WRONG RWY AND FLASHES ACFT LIGHTS AND INSTRUCTS THE C310 TO GAR. THE C310 CROSSED APPROX 50 FT ABOVE.

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WE WERE ACR; SLC DIRECT LAX; JAN/XX/98. IT WAS NIGHT; LOW CEILING (BUT VFR) AND FAIR VISIBILITY (MORE THAN 3 MI); WIND FROM N. ATIS RPTED USING RWYS 34L/34R AND 35. WE WERE CLRED TO TAXI TO RWY 35; XING RWY 34R AT TXWY H6; THEN (FOLLOWING A B737) VIA RWY 14; TO HOLD SHORT OF RWY 35. WHILE HOLDING SHORT ON RWY 32; A CIVILIAN CLRED TO LAND ON RWY 35 ATTEMPTED TO LAND ON RWY 32. I PUT ON ALL EXTERNAL LIGHTS AND DIRECTED A GAR ON TWR FREQ. THE CIVILIAN FLEW DIRECTLY OVER OUR B727; AND I ESTIMATE AT A HT OF LESS THAN 50 FT. A FALCON JET HOLDING SHORT ON THE OTHER SIDE OF RWY 35 CONFIRMED THE CIVILIAN'S FLT PATH. THE CIVILIAN APPEARED TO BE A LATE MODEL CESSNA TWIN. I BELIEVE SEVERAL FACTORS CONTRIBUTED TO THIS NEAR TRAGEDY. SLC TWR USES A RWY AS A TXWY. ESPECIALLY AT NIGHT; AND LESS THAN CLR WX; AND WITH RWY LIGHTS (VERSUS TXWY LIGHTS); THIS IS DANGEROUS. SLC TWR HAS NO PROC TO NOTIFY THE LNDG ACFT THAT ANOTHER ACFT IS ON NEARBY RWY 32; NOR DO THEY NOTIFY ACFT ON RWY 32 THAT THERE IS AN ACFT FLYING AN APCH TO NEARBY RWY 35. I DON'T BELIEVE THE TWR IS IN A POS PHYSICALLY TO MONITOR AND EVALUATE THE POS OF ACFT IN OUR SIT. WHEN I ASKED THE CTLR IF HE SAW WHAT JUST HAPPENED; I GOT NO RESPONSE. I SUGGEST: CHANGE TWR'S PROC TO NOTIFY ACFT OF OTHER ACFT WHEN OUR SIT ARISES. DO NOT ILLUMINATE A TXWY WITH RWY LIGHTS (HENCE; AT NIGHT; DON'T USE A RWY AS A TXWY). SUPPLEMENTAL INFO FROM ACN 391509: THE B737 WAS CLRED FOR TKOF. ON THE OTHER SIDE OF RWY 35 HOLDING SHORT WERE SEVERAL GA ACFT WAITING TO TKOF. A C172 WAS CLRED INTO POS AND HOLD RWY 35. IN THE MEAN TIME AN ACFT TURNING A VISUAL BASE TO RWY 35 APCH 1 1/2 MI WAS CLRED TO LAND RWY 35. DUE TO HIS CLOSENESS THE TWR INSTRUCTED THE C172 HOLDING; TO TAXI CLR OF RWY 35 ASAP. HE DID THIS BY TAXIING DOWN THE RWY TO THE FIRST INTXN APPROX 500 FT DOWN ASKING TWR WHICH WAY THEY WANTED HIM TO TURN L OR R. TWR SAID IT DIDN'T MATTER CALL CLR. THE TWR ASKED AGAIN IF THEY (C172) WAS CLR AND THEY ACKNOWLEDGED AFFIRMATIVE. AGAIN THE ACFT TURNING FINAL ON A R BASE ROLLED OUT ON FINAL FOR RWY 32. I WAS WATCHING OUT THE AFT SIDE AT THE CESSNA CLRING DOWN THE RWY. FORTUNATELY THE FO WAS WATCHING THE ACFT AND AS I TURNED BACK AND SAW WHAT WAS ABOUT TO HAPPEN (ACFT ON A 3/4 MI FINAL TO RWY 32). THE FO HAD A FEW MORE SECONDS TO DECIDE WHAT TO DO AND IMMEDIATELY TURNED ON ALL OUR TAXI AND LDNG LIGHTS; AND TOLD THE ACFT TO GAR. THE TWR WAS ASKED IF THEY SAW WHAT TOOK PLACE AND SAID NO. A FALCON JET ON THE PARALLEL TXWY CONFIRMED THE ACFT WENT DIRECTLY OVERHEAD AT A LOW ALT MY GUESS IS BTWN 50-100 FT. THIS WAS A REAL POTENTIAL FOR DISASTER. RWY 32 SHOULD NOT BE USED TO TAXI OUT TO RWY 35 AT NIGHT.