Narrative:

We were cleared via the snshn 3 RNAV departure for the first time for both the first officer and I. We briefed the departure thoroughly including terrain considerations and the two speed restrictions shown in magenta. We were given a revised 6000 ft restriction for traffic shortly after departure. After the 8000 ft restriction we continued to climb via the SID but were given a second altitude restriction of 11;000 ft for VFR traffic at 11;500 ft. It looked like a RA was a real possibility and we were both looking outside for the traffic. In the meantime the autopilot in VNAV accelerated out of 10;000 ft for the next speed restriction of 280 knots at livvi. Shortly thereafter we were given direct to xbbox and the autopilot began to accelerate to in excess of 300 knots per the climb page in the CDU. While we were discussing whether or not this new clearance allowed us to fly faster than 280 knots; ATC graciously gave us normal speed. At this point we realized that they were probably expecting us to [be] at 250 knots here per the first magenta note on the SID.looking back to the briefing at the gate; I don't think we fully understood what two magenta notes for two different speed restrictions meant as neither of us had seen something presented like this before. They seemed to almost be contradictory the way we interpreted them. Additionally; the distraction of the potential traffic conflict and terrain considerations caused us to overlook the speed restrictions.

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Original NASA ASRS Text

Title: B737NG Captain reported conflicting and confusing speed restrictions on the chart for the SNSHN THREE SID.

Narrative: We were cleared via the SNSHN 3 RNAV Departure for the first time for both the First Officer and I. We briefed the departure thoroughly including terrain considerations and the two speed restrictions shown in magenta. We were given a revised 6000 ft restriction for traffic shortly after departure. After the 8000 ft restriction we continued to climb via the SID but were given a second altitude restriction of 11;000 ft for VFR traffic at 11;500 ft. It looked like a RA was a real possibility and we were both looking outside for the traffic. In the meantime the autopilot in VNAV accelerated out of 10;000 ft for the next speed restriction of 280 knots at LIVVI. Shortly thereafter we were given direct to XBBOX and the autopilot began to accelerate to in excess of 300 knots per the climb page in the CDU. While we were discussing whether or not this new clearance allowed us to fly faster than 280 knots; ATC graciously gave us normal speed. At this point we realized that they were probably expecting us to [be] at 250 knots here per the first magenta note on the SID.Looking back to the briefing at the gate; I don't think we fully understood what two magenta notes for two different speed restrictions meant as neither of us had seen something presented like this before. They seemed to almost be contradictory the way we interpreted them. Additionally; the distraction of the potential traffic conflict and terrain considerations caused us to overlook the speed restrictions.

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.