Narrative:

We were level at 10000 ft on autoplt with altitude hold engaged on the moxee arrival into pdx. We had just received a frequency change from ZSE to portland approach when the TCASII gave us a TA. The intruding aircraft was 11:30 to 12 O'clock on our TCASII display and 500 ft below us. As the other aircraft approached, the vertical separation decreased to 200 ft and the TCASII issued an RA and commanded a climb. We complied with the TCASII command and climbed to 11200 ft when we received a clear of conflict. I notified ZSE immediately and then switched to portland approach control and advised them of the TCASII RA. We then resumed the arrival with no further problems. As we passed the other aircraft I saw it at our 9 O'clock position and slightly lower. We were advised it was an small aircraft. The initial TCASII alert occurred at about the same time as the frequency change and distracted us from changing frequencys immediately which prevented us from getting approach control advisories. However, the most concerning factor was that the intruding aircraft appeared to be climbing to our altitude on a collision course. Another factor in visually acquiring a small aircraft at our 12 O'clock position is the deck angle of our aircraft at 250 KTS, which does not allow good forward visibility without physically trying to look over the glare shield.

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Original NASA ASRS Text

Title: LGT HAS TCASII RA, COMPLIES WITH CLB.

Narrative: WE WERE LEVEL AT 10000 FT ON AUTOPLT WITH ALT HOLD ENGAGED ON THE MOXEE ARR INTO PDX. WE HAD JUST RECEIVED A FREQ CHANGE FROM ZSE TO PORTLAND APCH WHEN THE TCASII GAVE US A TA. THE INTRUDING ACFT WAS 11:30 TO 12 O'CLOCK ON OUR TCASII DISPLAY AND 500 FT BELOW US. AS THE OTHER ACFT APCHED, THE VERT SEPARATION DECREASED TO 200 FT AND THE TCASII ISSUED AN RA AND COMMANDED A CLB. WE COMPLIED WITH THE TCASII COMMAND AND CLBED TO 11200 FT WHEN WE RECEIVED A CLR OF CONFLICT. I NOTIFIED ZSE IMMEDIATELY AND THEN SWITCHED TO PORTLAND APCH CTL AND ADVISED THEM OF THE TCASII RA. WE THEN RESUMED THE ARR WITH NO FURTHER PROBS. AS WE PASSED THE OTHER ACFT I SAW IT AT OUR 9 O'CLOCK POS AND SLIGHTLY LOWER. WE WERE ADVISED IT WAS AN SMA. THE INITIAL TCASII ALERT OCCURRED AT ABOUT THE SAME TIME AS THE FREQ CHANGE AND DISTRACTED US FROM CHANGING FREQS IMMEDIATELY WHICH PREVENTED US FROM GETTING APCH CTL ADVISORIES. HOWEVER, THE MOST CONCERNING FACTOR WAS THAT THE INTRUDING ACFT APPEARED TO BE CLBING TO OUR ALT ON A COLLISION COURSE. ANOTHER FACTOR IN VISUALLY ACQUIRING A SMALL ACFT AT OUR 12 O'CLOCK POS IS THE DECK ANGLE OF OUR ACFT AT 250 KTS, WHICH DOES NOT ALLOW GOOD FORWARD VISIBILITY WITHOUT PHYSICALLY TRYING TO LOOK OVER THE GLARE SHIELD.

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.