Narrative:

I was working D76 at ZJX when a DA01 said he had engine problem. (I am a pilot, the radar controller was not.) so I asked pilot on frequency if he was declaring an emergency, or had to shut it down. He said no, but he waited to change destination to tlh. I decided to descend to a lower altitude. Radar controller then gave him FL350 and direct tlh which turned him directly over an air carrier MD80 northbound on J81. About 5 mi east of the air carrier, the DA01 said he had to shut down the engine and had to have a lower altitude and could not maintain altitude. After being told to maintain FL350 he came back and said again he could not maintain altitude now at FL345. The air carrier interrupts and says he has a TCASII alert and he is descending. Both targets are on a perfect merger course. Radar controller froze, so I took frequency and told the air carrier not to descend and to turn left to 090 degrees immediately, if he descends it would put him with the DA10 who had lost an engine and was descending. The 2 aircraft got each other in sight and missed in very close proximity. TCASII almost put these 2 aircraft together! I only reacted to what at the time seemed to be the best solution.

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Original NASA ASRS Text

Title: OPERROR OCCURRED WHEN A DA10 COULD NOT HOLD ALT AFTER LOSING AN ENG AND DSNDED THROUGH THE ALT OF THE ACR MD80. THE MD80 RECEIVED A TCASII RA AND BEGAN DSCNT. THE RPTR SAYS THE RADAR CTLR FROZE. THE RPTR TOOK ACTION TO STOP THE DSCNT AND TURNED THE ACFT AWAY FROM THE DA10.

Narrative: I WAS WORKING D76 AT ZJX WHEN A DA01 SAID HE HAD ENG PROB. (I AM A PLT, THE RADAR CTLR WAS NOT.) SO I ASKED PLT ON FREQ IF HE WAS DECLARING AN EMER, OR HAD TO SHUT IT DOWN. HE SAID NO, BUT HE WAITED TO CHANGE DEST TO TLH. I DECIDED TO DSND TO A LOWER ALT. RADAR CTLR THEN GAVE HIM FL350 AND DIRECT TLH WHICH TURNED HIM DIRECTLY OVER AN ACR MD80 NBOUND ON J81. ABOUT 5 MI E OF THE ACR, THE DA01 SAID HE HAD TO SHUT DOWN THE ENG AND HAD TO HAVE A LOWER ALT AND COULD NOT MAINTAIN ALT. AFTER BEING TOLD TO MAINTAIN FL350 HE CAME BACK AND SAID AGAIN HE COULD NOT MAINTAIN ALT NOW AT FL345. THE ACR INTERRUPTS AND SAYS HE HAS A TCASII ALERT AND HE IS DSNDING. BOTH TARGETS ARE ON A PERFECT MERGER COURSE. RADAR CTLR FROZE, SO I TOOK FREQ AND TOLD THE ACR NOT TO DSND AND TO TURN L TO 090 DEGS IMMEDIATELY, IF HE DSNDS IT WOULD PUT HIM WITH THE DA10 WHO HAD LOST AN ENG AND WAS DSNDING. THE 2 ACFT GOT EACH OTHER IN SIGHT AND MISSED IN VERY CLOSE PROX. TCASII ALMOST PUT THESE 2 ACFT TOGETHER! I ONLY REACTED TO WHAT AT THE TIME SEEMED TO BE THE BEST SOLUTION.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.