Narrative:

Center pointed out traffic which we found on TCASII and acquired visually. Center cleared us to climb past the VFR small plane, and we did so, turning into it slightly to comply with the SID. We had a good rate of climb going when the TCASII directed us to descend immediately. There was no way to descend without climbing through the VFR aircraft's altitude anyway, (especially considering the people in the cabin) so I increased the rate of climb instead to minimize time at target's altitude. Safety was not compromised since I kept the other aircraft in sight and the miss distance was about 1000 ft as I passed through its altitude. Although I am a proponent of TCASII, I must comment that it appears to be programmed without respect to aircraft capability. My best judgement told me to do just the opposite of the TCASII command, even knowing that the other aircraft might be responding to his TCASII and my actions might be thwarting the coordination between system. Of course, in IMC conditions I would have followed the TCASII commands, but it is scary to know that it might actually increase exposure to mid-air risk.

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Original NASA ASRS Text

Title: CAPT OF AN MLG INCREASED THE RATE OF CLB IN RESPONSE TO OBSERVATION OF A CONFLICTING TFC, TCASII AND AN ATC ADVISORY.

Narrative: CTR POINTED OUT TFC WHICH WE FOUND ON TCASII AND ACQUIRED VISUALLY. CTR CLRED US TO CLB PAST THE VFR SMALL PLANE, AND WE DID SO, TURNING INTO IT SLIGHTLY TO COMPLY WITH THE SID. WE HAD A GOOD RATE OF CLB GOING WHEN THE TCASII DIRECTED US TO DSND IMMEDIATELY. THERE WAS NO WAY TO DSND WITHOUT CLBING THROUGH THE VFR ACFT'S ALT ANYWAY, (ESPECIALLY CONSIDERING THE PEOPLE IN THE CABIN) SO I INCREASED THE RATE OF CLB INSTEAD TO MINIMIZE TIME AT TARGET'S ALT. SAFETY WAS NOT COMPROMISED SINCE I KEPT THE OTHER ACFT IN SIGHT AND THE MISS DISTANCE WAS ABOUT 1000 FT AS I PASSED THROUGH ITS ALT. ALTHOUGH I AM A PROPONENT OF TCASII, I MUST COMMENT THAT IT APPEARS TO BE PROGRAMMED WITHOUT RESPECT TO ACFT CAPABILITY. MY BEST JUDGEMENT TOLD ME TO DO JUST THE OPPOSITE OF THE TCASII COMMAND, EVEN KNOWING THAT THE OTHER ACFT MIGHT BE RESPONDING TO HIS TCASII AND MY ACTIONS MIGHT BE THWARTING THE COORD BTWN SYS. OF COURSE, IN IMC CONDITIONS I WOULD HAVE FOLLOWED THE TCASII COMMANDS, BUT IT IS SCARY TO KNOW THAT IT MIGHT ACTUALLY INCREASE EXPOSURE TO MID-AIR RISK.

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.