Narrative:

Departed melbourne, fl, in clear WX on scheduled flight to atl. Mlb departure cleared us directly to orl and handed us off to mco approach/departure control. We were then given a heading of 330 degrees to intercept J53 north of orl and a climb to 14000 ft. After a few mins, we were issued a new intercept heading of 320 degrees. We were also asked our airspeed which was 335 KIAS out of 10000 ft. Shortly, we sighted a departure out of mco at about our 11 O'clock position heading approximately north at perhaps 10 mi. I thought that the 320 degree vector was to pass us behind him. Then I saw him start a slight left turn which I knew was meant to intercept J53. Our TCASII showed him to be lower than us, but climbing. As we left 13000 ft mco departure control handed us off to ZJX. I reported into ZJX, noticing that we had a high rate of overtake on the traffic. We were leveling at 14000 ft and we were going to pass directly over him in the same direction. He was still climbing, now 2500 ft lower than us. I asked ZJX at what altitude that aircraft would level. ZJX was not controling him and did not know. I told ZJX that we were uncomfortable with the situation and wanted a turn. ZJX said no to the turn, but gave us 15000 ft. We started our climb as the air carrier Y jet began to pass under our nose. It looked like we were set up for a carrier landing on his back. He was still climbing, now 1500 ft lower than us and closing. As I lost sight of him under our nose, I told the first officer to break right immediately. I told ZJX what we were doing, as simultaneously, our TCASII conflict alert went off. ZJX told us they could not authority/authorized the turn. I acknowledged and told them of the TCASII warning. We turned approximately 30 degrees to the right of course for 2 mins or less and then corrected back to course. Conclusions: I remember hearing mco departure talking to an air carrier Y heavy jet. I could not see that aircraft visually or on the TCASII and didn't pay a lot of attention to the xmissions. Mco departure never mentioned the jet to us. In retrospect, if I had been more cognizant of mco departure's instructions to air carrier Y and if mco had told me about the Y jet, I would have been aware of his clearance and intentions. This could have helped to defuse a very unnerving event.

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Original NASA ASRS Text

Title: HDG TRACK DEV EXECUTED BY ACR WHEN CLBING TFC SIGHTED.

Narrative: DEPARTED MELBOURNE, FL, IN CLR WX ON SCHEDULED FLT TO ATL. MLB DEP CLRED US DIRECTLY TO ORL AND HANDED US OFF TO MCO APCH/DEP CTL. WE WERE THEN GIVEN A HDG OF 330 DEGS TO INTERCEPT J53 N OF ORL AND A CLB TO 14000 FT. AFTER A FEW MINS, WE WERE ISSUED A NEW INTERCEPT HDG OF 320 DEGS. WE WERE ALSO ASKED OUR AIRSPD WHICH WAS 335 KIAS OUT OF 10000 FT. SHORTLY, WE SIGHTED A DEP OUT OF MCO AT ABOUT OUR 11 O'CLOCK POS HDG APPROX N AT PERHAPS 10 MI. I THOUGHT THAT THE 320 DEG VECTOR WAS TO PASS US BEHIND HIM. THEN I SAW HIM START A SLIGHT L TURN WHICH I KNEW WAS MEANT TO INTERCEPT J53. OUR TCASII SHOWED HIM TO BE LOWER THAN US, BUT CLBING. AS WE LEFT 13000 FT MCO DEP CTL HANDED US OFF TO ZJX. I RPTED INTO ZJX, NOTICING THAT WE HAD A HIGH RATE OF OVERTAKE ON THE TFC. WE WERE LEVELING AT 14000 FT AND WE WERE GOING TO PASS DIRECTLY OVER HIM IN THE SAME DIRECTION. HE WAS STILL CLBING, NOW 2500 FT LOWER THAN US. I ASKED ZJX AT WHAT ALT THAT ACFT WOULD LEVEL. ZJX WAS NOT CTLING HIM AND DID NOT KNOW. I TOLD ZJX THAT WE WERE UNCOMFORTABLE WITH THE SIT AND WANTED A TURN. ZJX SAID NO TO THE TURN, BUT GAVE US 15000 FT. WE STARTED OUR CLB AS THE ACR Y JET BEGAN TO PASS UNDER OUR NOSE. IT LOOKED LIKE WE WERE SET UP FOR A CARRIER LNDG ON HIS BACK. HE WAS STILL CLBING, NOW 1500 FT LOWER THAN US AND CLOSING. AS I LOST SIGHT OF HIM UNDER OUR NOSE, I TOLD THE FO TO BREAK R IMMEDIATELY. I TOLD ZJX WHAT WE WERE DOING, AS SIMULTANEOUSLY, OUR TCASII CONFLICT ALERT WENT OFF. ZJX TOLD US THEY COULD NOT AUTH THE TURN. I ACKNOWLEDGED AND TOLD THEM OF THE TCASII WARNING. WE TURNED APPROX 30 DEGS TO THE R OF COURSE FOR 2 MINS OR LESS AND THEN CORRECTED BACK TO COURSE. CONCLUSIONS: I REMEMBER HEARING MCO DEP TALKING TO AN ACR Y HVY JET. I COULD NOT SEE THAT ACFT VISUALLY OR ON THE TCASII AND DIDN'T PAY A LOT OF ATTN TO THE XMISSIONS. MCO DEP NEVER MENTIONED THE JET TO US. IN RETROSPECT, IF I HAD BEEN MORE COGNIZANT OF MCO DEP'S INSTRUCTIONS TO ACR Y AND IF MCO HAD TOLD ME ABOUT THE Y JET, I WOULD HAVE BEEN AWARE OF HIS CLRNC AND INTENTIONS. THIS COULD HAVE HELPED TO DEFUSE A VERY UNNERVING EVENT.

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.