Narrative:

While descending to 7000 ft, our cleared altitude, at about 7200 ft we got a 'TA' from the TCASII. I observed a target on the TCASII screen at 12 O'clock and quite close. I T had no altitude reporting. Both pilots immediately began searching outside for the traffic. Suddenly, the 'altitude alert' went off. We had gone through 7000 ft while looking for the traffic. We leveled off about 250 ft below 7000 ft and climbed back to 7000 ft. At the same time, I looked at the TCASII screen and the 'TA' target was gone. It is almost impossible for a pilot to not search outside for a 'TA' from TCASII. Even though you have been watching for traffic, this can cause a distraction from flying the airplane. I have noticed that at times, TCASII targets suddenly appear and disappear. Maybe caused by the airframe blanking transponder signals from certain angles. The target in this report suddenly appeared, caused a 'TA' and distracted the crew just as we should have been leveling off. I don't know the answer to the problem of possible distrs caused by TCASII. It can be a problem and seems to be a normal human reaction to a warning. I have over 1 yr of experience flying with TCASII installed in my airplane. This specific traffic was never sighted visually. Supplemental information from acn 215432: I believe the advantages of TCASII far outweigh the distraction it can occasionally cause.

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Original NASA ASRS Text

Title: MLG FLC HAS TCASII TA. LOOKING OUTSIDE, THEY NEGLECT TO LEVEL OFF. ALT ALERT GOES OFF, RETURN TO ASSIGNED.

Narrative: WHILE DSNDING TO 7000 FT, OUR CLRED ALT, AT ABOUT 7200 FT WE GOT A 'TA' FROM THE TCASII. I OBSERVED A TARGET ON THE TCASII SCREEN AT 12 O'CLOCK AND QUITE CLOSE. I T HAD NO ALT RPTING. BOTH PLTS IMMEDIATELY BEGAN SEARCHING OUTSIDE FOR THE TFC. SUDDENLY, THE 'ALT ALERT' WENT OFF. WE HAD GONE THROUGH 7000 FT WHILE LOOKING FOR THE TFC. WE LEVELED OFF ABOUT 250 FT BELOW 7000 FT AND CLBED BACK TO 7000 FT. AT THE SAME TIME, I LOOKED AT THE TCASII SCREEN AND THE 'TA' TARGET WAS GONE. IT IS ALMOST IMPOSSIBLE FOR A PLT TO NOT SEARCH OUTSIDE FOR A 'TA' FROM TCASII. EVEN THOUGH YOU HAVE BEEN WATCHING FOR TFC, THIS CAN CAUSE A DISTR FROM FLYING THE AIRPLANE. I HAVE NOTICED THAT AT TIMES, TCASII TARGETS SUDDENLY APPEAR AND DISAPPEAR. MAYBE CAUSED BY THE AIRFRAME BLANKING TRANSPONDER SIGNALS FROM CERTAIN ANGLES. THE TARGET IN THIS RPT SUDDENLY APPEARED, CAUSED A 'TA' AND DISTRACTED THE CREW JUST AS WE SHOULD HAVE BEEN LEVELING OFF. I DON'T KNOW THE ANSWER TO THE PROBLEM OF POSSIBLE DISTRS CAUSED BY TCASII. IT CAN BE A PROBLEM AND SEEMS TO BE A NORMAL HUMAN REACTION TO A WARNING. I HAVE OVER 1 YR OF EXPERIENCE FLYING WITH TCASII INSTALLED IN MY AIRPLANE. THIS SPECIFIC TFC WAS NEVER SIGHTED VISUALLY. SUPPLEMENTAL INFO FROM ACN 215432: I BELIEVE THE ADVANTAGES OF TCASII FAR OUTWEIGH THE DISTR IT CAN OCCASIONALLY CAUSE.

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.