Narrative:

We were told to maintain visual separation behind an light transport Y which was just departing. We were cleared for takeoff at what I would estimate was the minimum required separation of 6000 ft between us and the light transport Y. I was not familiar with the performance characteristics of the light transport Y, but believed it would easily outrun our light transport X. I climbed out at the recommended profile speeds, but was surprised to find that we were rapidly overtaking the light transport Y. We had both been assigned a 270 degree heading, and I began a turn to the right to overtake the light transport Y on the right side. I also started to climb faster when the light transport Y suddenly began a right turn. The light transport Y pilot told ATC that his TCASII had shown a target closing rapidly from the rear, 200 ft below and 'climbing at an extraordinary rate,' so he elected to turn right and clear our path. However, at the time he turned, I was already at least 200 ft above him and on his right side. The light transport Y pilot stated that he did not believe that I ever had him in sight, but it was apparent that once he was cleared for takeoff, he lost all situational awareness of what was happening behind him. Contributing factors: 1) ATC's failure to assign diverging headings, 2) failure of the light transport Y pilot to realize that we had him in sight, 3) inadequate or misinterpreted TCASII RA, 4) my assumption that the bigger airplane would be faster.

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Original NASA ASRS Text

Title: 2 ACR LTTS CHOSE TO SEPARATE THEMSELVES USING TCASII.

Narrative: WE WERE TOLD TO MAINTAIN VISUAL SEPARATION BEHIND AN LTT Y WHICH WAS JUST DEPARTING. WE WERE CLRED FOR TKOF AT WHAT I WOULD ESTIMATE WAS THE MINIMUM REQUIRED SEPARATION OF 6000 FT BTWN US AND THE LTT Y. I WAS NOT FAMILIAR WITH THE PERFORMANCE CHARACTERISTICS OF THE LTT Y, BUT BELIEVED IT WOULD EASILY OUTRUN OUR LTT X. I CLBED OUT AT THE RECOMMENDED PROFILE SPDS, BUT WAS SURPRISED TO FIND THAT WE WERE RAPIDLY OVERTAKING THE LTT Y. WE HAD BOTH BEEN ASSIGNED A 270 DEG HDG, AND I BEGAN A TURN TO THE R TO OVERTAKE THE LTT Y ON THE R SIDE. I ALSO STARTED TO CLB FASTER WHEN THE LTT Y SUDDENLY BEGAN A R TURN. THE LTT Y PLT TOLD ATC THAT HIS TCASII HAD SHOWN A TARGET CLOSING RAPIDLY FROM THE REAR, 200 FT BELOW AND 'CLBING AT AN EXTRAORDINARY RATE,' SO HE ELECTED TO TURN R AND CLR OUR PATH. HOWEVER, AT THE TIME HE TURNED, I WAS ALREADY AT LEAST 200 FT ABOVE HIM AND ON HIS R SIDE. THE LTT Y PLT STATED THAT HE DID NOT BELIEVE THAT I EVER HAD HIM IN SIGHT, BUT IT WAS APPARENT THAT ONCE HE WAS CLRED FOR TKOF, HE LOST ALL SITUATIONAL AWARENESS OF WHAT WAS HAPPENING BEHIND HIM. CONTRIBUTING FACTORS: 1) ATC'S FAILURE TO ASSIGN DIVERGING HDGS, 2) FAILURE OF THE LTT Y PLT TO REALIZE THAT WE HAD HIM IN SIGHT, 3) INADEQUATE OR MISINTERPRETED TCASII RA, 4) MY ASSUMPTION THAT THE BIGGER AIRPLANE WOULD BE FASTER.

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.