Narrative:

Cleared to sea via olympia 1 arrival, to cross olm at 12000 ft then descend to 10000 ft. Outbound from the olm VOR on the 019 degree radial descending to 10000 ft, a TCASII TA alert indicated traffic at 12 O'clock, 6 mi at 10000 ft. After only 1 TA alert, a TCASII RA alert immediately followed with a 2000 FPM pull up commanded. An emergency pull up was begun at 10200 ft. During the pull-up a white mdt aircraft passed directly under our nose on a reciprocal heading at an indicated 10000 ft. Miss distance 500 vertical ft or less. TCASII clear of traffic sounded at 11200 ft and arrival to sea was continued. Entire TCASII event lasted less than 1 min. The approach controller was informed of the incident and was told that a 'near miss' had occurred. He replied that he had not previously seen the traffic but he now saw the traffic. He stated that he was not controling the traffic, nor was the traffic on his frequency. He also made a statement that he had been distraction from his control duties by an equipment failure of some kind. It is my opinion that the TCASII RA command and the execution of SOP procedures saved this aircraft from a midair collision.

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Original NASA ASRS Text

Title: LGT HAS NMAC WITH MDT DURING DSCNT. TCASII RA SAVES THE DAY.

Narrative: CLRED TO SEA VIA OLYMPIA 1 ARR, TO CROSS OLM AT 12000 FT THEN DSND TO 10000 FT. OUTBOUND FROM THE OLM VOR ON THE 019 DEG RADIAL DSNDING TO 10000 FT, A TCASII TA ALERT INDICATED TFC AT 12 O'CLOCK, 6 MI AT 10000 FT. AFTER ONLY 1 TA ALERT, A TCASII RA ALERT IMMEDIATELY FOLLOWED WITH A 2000 FPM PULL UP COMMANDED. AN EMER PULL UP WAS BEGUN AT 10200 FT. DURING THE PULL-UP A WHITE MDT ACFT PASSED DIRECTLY UNDER OUR NOSE ON A RECIPROCAL HDG AT AN INDICATED 10000 FT. MISS DISTANCE 500 VERT FT OR LESS. TCASII CLR OF TFC SOUNDED AT 11200 FT AND ARR TO SEA WAS CONTINUED. ENTIRE TCASII EVENT LASTED LESS THAN 1 MIN. THE APCH CTLR WAS INFORMED OF THE INCIDENT AND WAS TOLD THAT A 'NEAR MISS' HAD OCCURRED. HE REPLIED THAT HE HAD NOT PREVIOUSLY SEEN THE TFC BUT HE NOW SAW THE TFC. HE STATED THAT HE WAS NOT CTLING THE TFC, NOR WAS THE TFC ON HIS FREQ. HE ALSO MADE A STATEMENT THAT HE HAD BEEN DISTR FROM HIS CTL DUTIES BY AN EQUIP FAILURE OF SOME KIND. IT IS MY OPINION THAT THE TCASII RA COMMAND AND THE EXECUTION OF SOP PROCS SAVED THIS ACFT FROM A MIDAIR COLLISION.

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.