Narrative:

I was captain and monitoring pilot. During departure approaching 10;000 feet on the RNAV SID; we received a TCAS traffic alert in red with the target of interest at approximately 2 o'clock; 600 feet above; level; within 7 miles. I called out the details to the first office (pilot flying) hand flying; and within a short time; observed that the TCAS target was now 400 feet above and converging. At that point we received a TCAS resolution advisory; emitting a descend command; followed about 5 seconds later by level off. I observed the first officer immediately respond in accordance with the TCAS visual cues and aural commands; resulting in a reversal of the climb from approximately 10;300 feet to approximately 9;800 feet. The aircraft exceeded 250 knots below 10;000 during the evasive action. I acquired the target visually; a cirrus-type directly above; crossing from our 1 o'clock to 5 o'clock. We were shortly thereafter clear of conflict; and resumed the climb. I reported to ATC that we had responded to a TCAS RA; and were continuing the climb.the cirrus appeared to be above the ceiling of the las vegas class B; westbound; apparently level at 10;500 feet. We were flying the SID as cleared. There was no traffic advisory from ATC. The most likely probable cause is a momentary loss of situational awareness on the part of the corresponding departure control sector. The controller mentioned merged data blocks from returning helicopters. Secondary radar technology should be improved to eliminate merger or overlapping data blocks.

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Original NASA ASRS Text

Title: B737-800 Captain reported an NMAC and complied with a TCAS RA to avoid traffic not issued by ATC.

Narrative: I was Captain and monitoring pilot. During departure approaching 10;000 feet on the RNAV SID; we received a TCAS Traffic Alert in red with the target of interest at approximately 2 o'clock; 600 feet above; level; within 7 miles. I called out the details to the First Office (pilot flying) hand flying; and within a short time; observed that the TCAS target was now 400 feet above and converging. At that point we received a TCAS Resolution Advisory; emitting a descend command; followed about 5 seconds later by level off. I observed the First Officer immediately respond in accordance with the TCAS visual cues and aural commands; resulting in a reversal of the climb from approximately 10;300 feet to approximately 9;800 feet. The aircraft exceeded 250 Knots below 10;000 during the evasive action. I acquired the target visually; a Cirrus-type directly above; crossing from our 1 o'clock to 5 o'clock. We were shortly thereafter clear of conflict; and resumed the climb. I reported to ATC that we had responded to a TCAS RA; and were continuing the climb.The Cirrus appeared to be above the ceiling of the Las Vegas Class B; westbound; apparently level at 10;500 feet. We were flying the SID as cleared. There was no traffic advisory from ATC. The most likely probable cause is a momentary loss of situational awareness on the part of the corresponding departure control sector. The controller mentioned merged data blocks from returning helicopters. Secondary radar technology should be improved to eliminate merger or overlapping data blocks.

Data retrieved from NASA's ASRS site 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.