Narrative:

While being vectored for ILS runway 36L at clt, we were advised of the other aircraft west of our position that was being vectored for the ILS runway 36R. He was at 3600 ft and we were cleared to 4600 ft. First officer was flying the aircraft on autoplt. At approximately +/-4700 ft, I diverted my attention to the TCASII. I queried the first officer that we were going to the left side and the other aircraft was going to the right side. He responded with an affirmative. I watched the TCASII as our flight paths grew closer. Unaware, the first officer continued the descent through 4600 ft. I continued to focus on the TCASII. We received a TA and I responded that this does not look right. At that time approach control called to confirm our altitude at 4600 ft. Realizing our error (I saw us down to 4200 ft) we immediately climbed back up to 4600 ft. During the correction we received an RA to 'climb.' we leveled off at 4600 ft and completed the flight without further incident. Some contributing factors: 1) one pilot must fly the aircraft at all times while the PNF must continue to monitor all aspects of the flight. 2) I think crossing the approach paths of 2 different aircraft in IMC diverted our attention to the TCASII. 3) even unaware of the altitude deviation I should have reacted quicker to what I was seeing on the TCASII. In the future I will be careful not to channelize my attention on 1 area (TCASII) and monitor the flight. Supplemental information from acn 359627: RA sounded as recovery was initiated. During the conflict we were IFR and never saw other aircraft. Reviewing conflict I cannot believe I broke rule #1: fly the airplane! I allowed myself to be distraction. This is especially frustrating to me as I had briefed the unusual pattern we would be doing (right base for runway 36L) and the potential for conflict with possible traffic on runway 36R.

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Original NASA ASRS Text

Title: NMAC BTWN XING TFC DURING RADAR VECTORING FOR AN IAP ILS APCH.

Narrative: WHILE BEING VECTORED FOR ILS RWY 36L AT CLT, WE WERE ADVISED OF THE OTHER ACFT W OF OUR POS THAT WAS BEING VECTORED FOR THE ILS RWY 36R. HE WAS AT 3600 FT AND WE WERE CLRED TO 4600 FT. FO WAS FLYING THE ACFT ON AUTOPLT. AT APPROX +/-4700 FT, I DIVERTED MY ATTN TO THE TCASII. I QUERIED THE FO THAT WE WERE GOING TO THE L SIDE AND THE OTHER ACFT WAS GOING TO THE R SIDE. HE RESPONDED WITH AN AFFIRMATIVE. I WATCHED THE TCASII AS OUR FLT PATHS GREW CLOSER. UNAWARE, THE FO CONTINUED THE DSCNT THROUGH 4600 FT. I CONTINUED TO FOCUS ON THE TCASII. WE RECEIVED A TA AND I RESPONDED THAT THIS DOES NOT LOOK RIGHT. AT THAT TIME APCH CTL CALLED TO CONFIRM OUR ALT AT 4600 FT. REALIZING OUR ERROR (I SAW US DOWN TO 4200 FT) WE IMMEDIATELY CLBED BACK UP TO 4600 FT. DURING THE CORRECTION WE RECEIVED AN RA TO 'CLB.' WE LEVELED OFF AT 4600 FT AND COMPLETED THE FLT WITHOUT FURTHER INCIDENT. SOME CONTRIBUTING FACTORS: 1) ONE PLT MUST FLY THE ACFT AT ALL TIMES WHILE THE PNF MUST CONTINUE TO MONITOR ALL ASPECTS OF THE FLT. 2) I THINK XING THE APCH PATHS OF 2 DIFFERENT ACFT IN IMC DIVERTED OUR ATTN TO THE TCASII. 3) EVEN UNAWARE OF THE ALTDEV I SHOULD HAVE REACTED QUICKER TO WHAT I WAS SEEING ON THE TCASII. IN THE FUTURE I WILL BE CAREFUL NOT TO CHANNELIZE MY ATTN ON 1 AREA (TCASII) AND MONITOR THE FLT. SUPPLEMENTAL INFO FROM ACN 359627: RA SOUNDED AS RECOVERY WAS INITIATED. DURING THE CONFLICT WE WERE IFR AND NEVER SAW OTHER ACFT. REVIEWING CONFLICT I CANNOT BELIEVE I BROKE RULE #1: FLY THE AIRPLANE! I ALLOWED MYSELF TO BE DISTR. THIS IS ESPECIALLY FRUSTRATING TO ME AS I HAD BRIEFED THE UNUSUAL PATTERN WE WOULD BE DOING (R BASE FOR RWY 36L) AND THE POTENTIAL FOR CONFLICT WITH POSSIBLE TFC ON RWY 36R.

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.