ACR AND SPC ACFT WERE HEAD ON AT THE SAME ALT. THE SPC DECLARED AN EMER CAUSING THE CTLR TO AVERT HIS ATTN FROM THE IMPENDING CONFLICT. TCASII IN THE ACR ACFT MADE CONFUSING AND CONFLICTING COMMANDS THAT FURTHER COMPLICATED THE SITUATION. ATC GAVE THE SPC A TURN THAT; IN CONJUNCTION WITH THE ALT DEVS OF THE ACR; RESOLVED THE CONFLICT.

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WE HAD JUST SWITCHED TO DEP CTL AND LEVELED AT 5000 FT; 250 KTS (AUTOPLT ON). I NOTICED ANOTHER ACFT ON TCASII AT 12 O'CLOCK; ABOUT 5 MI; SAME ALT; CONSTANT BEARING; DECREASING RANGE. SPC HAD JUST DECLARED AN EMER FOR SHUTDOWN OF #4 ENG (LOSS OF OIL PRESSURE). THE CTLR WAS BUSY WITH FOB; SOULS; ETC; AND WE WERE UNABLE TO TELL HIM OF THE TFC CONFLICT. TCASII ANNOUNCED 'TFC; TFC.' THE FO AND I BOTH ACQUIRED THE OTHER ACFT VISUALLY BUT VISIBILITY WAS RESTR TO LESS THAN 5 MI IN HAZE. (ALL OF THIS HAPPENED IN A MATTER OF SECONDS.) THE TCASII COMMANDED 'DSND; DSND.' IN MY OPINION WE WERE GOING TO BE VERY CLOSE (OR WORSE) IF WE CONTINUED ON PRESENT ALT AND HDG. I DISCONNECTED THE AUTOPLT; PULLED THE PWR TO IDLE AND BEGAN AN IMMEDIATE 1500 FPM DSCNT. AT 4700 FT THE TCASII SAID 'CLR OF CONFLICT.' WE STARTED A SLOW CLB BACK TOWARD 5000 FT. AT THIS TIME THE CTLR TURNED THE SPC AND COMMANDED US TO CLB TO 6000 FT. THE TCASII THEN COMMANDED 'CLB; CLB.' WE BEGAN A 2000 FPM CLB. UPON PASSING 5000 FT; TCASII REVERSED AND SAID 'DSND; DSND.' AS WE WERE ALREADY PASSING THROUGH THE SPC'S ALT; HAD HIM VISUALLY; HAD BEEN ISSUED A CLB CLRNC; AND WERE NOT GOING TO COLLIDE; I IGNORED THE 'DSND' COMMAND (WHICH QUICKLY CHANGED TO 'CLR OF CONFLICT') AND CONTINUED TO CLB. I AM CONCERNED ABOUT THE 1) 'DSND'; 2) 'ALL CLR'; 3) 'CLB' AND THEN; 4) 'DSND' COMMANDS. TCASII AVERTED A POSSIBLE NEAR MISS (OR WORSE).