Narrative:

Our original ATC clearance was via the mountain 2 departure to maintain 9000 ft. About 4 mi after takeoff from runway 34L, seattle departure control told us to maintain 5000 ft due to traffic at 12 O'clock at 6000 ft. At about the same time, the TCASII called out 'traffic, traffic' which was for another target to the west of us. That target had no altitude readout, therefore we made no effort to find it visually. We still had not seen the 6000 ft traffic, when the TCASII sounded 'traffic, traffic' once again. In fact, within the next min, there were at least 4 more TCASII prompts for other targets. As it turns out, those targets probably were associated with boeing field. While this was going on, we did not turn at the 8 DME point on the departure, but continued on and at about the 13 DME point, as I was about to start a turn to the east, departure control asked if we had received the mountain 2 departure. We responded that we had, and were then instructed to turn to a heading of 110 degrees for vectors en route. TCASII is a very useful tool, and has in my experience played a very important role in flight safety, however this time it almost overloaded our crew and was very distracting at a critical time of our flight.

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Original NASA ASRS Text

Title: CAPT OF ACR LGT ACFT DEV FROM THE TRACK OF A SID DUE TO LOOKING FOR TFC WARNINGS OF ACFT TCASII.

Narrative: OUR ORIGINAL ATC CLRNC WAS VIA THE MOUNTAIN 2 DEP TO MAINTAIN 9000 FT. ABOUT 4 MI AFTER TKOF FROM RWY 34L, SEATTLE DEP CTL TOLD US TO MAINTAIN 5000 FT DUE TO TFC AT 12 O'CLOCK AT 6000 FT. AT ABOUT THE SAME TIME, THE TCASII CALLED OUT 'TFC, TFC' WHICH WAS FOR ANOTHER TARGET TO THE W OF US. THAT TARGET HAD NO ALT READOUT, THEREFORE WE MADE NO EFFORT TO FIND IT VISUALLY. WE STILL HAD NOT SEEN THE 6000 FT TFC, WHEN THE TCASII SOUNDED 'TFC, TFC' ONCE AGAIN. IN FACT, WITHIN THE NEXT MIN, THERE WERE AT LEAST 4 MORE TCASII PROMPTS FOR OTHER TARGETS. AS IT TURNS OUT, THOSE TARGETS PROBABLY WERE ASSOCIATED WITH BOEING FIELD. WHILE THIS WAS GOING ON, WE DID NOT TURN AT THE 8 DME POINT ON THE DEP, BUT CONTINUED ON AND AT ABOUT THE 13 DME POINT, AS I WAS ABOUT TO START A TURN TO THE E, DEP CTL ASKED IF WE HAD RECEIVED THE MOUNTAIN 2 DEP. WE RESPONDED THAT WE HAD, AND WERE THEN INSTRUCTED TO TURN TO A HDG OF 110 DEGS FOR VECTORS ENRTE. TCASII IS A VERY USEFUL TOOL, AND HAS IN MY EXPERIENCE PLAYED A VERY IMPORTANT ROLE IN FLT SAFETY, HOWEVER THIS TIME IT ALMOST OVERLOADED OUR CREW AND WAS VERY DISTRACTING AT A CRITICAL TIME OF OUR FLT.

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.