Narrative:

Descending via the tmbrs 2 RNAV arrival to pdx. I was the pm and we were cleared direct to tmbrs intersection and to descend. About 30 miles prior to tmbrs ATC asked our speed. 320 kts. We were advised there is a 280 KIAS speed restriction but because we were cleared direct to tmbrs and not yet on a descend via clearance we did not think this speed restriction applied. Actually; the speed restriction note on the STAR is new to both the crew members. Usually a ball note or speed limiting procedure is noted near to the mapped routing or intersection but this speed restriction small box was to the side of the route...a new convention to both of us. I am still not clear that we needed to abide by this restriction as we were not cleared to descend via that arrival and; in fact; had not yet begun any portion of the arrival as we were still flying direct to a fix on the STAR; but the controller was agitated nonetheless. Then; just as we were recovering from that episode and I was saying it myself to focus and do not be distracted by the incident and pay attention so as not to make another error...we made another error. We were now cleared to descend via the tmbrs 2 arrival 'landing west' and the FMS was programmed and all the database altitude and speed restrictions were confirmed with the chart. I then put my head down to work on another task and soon the PF let out a 'what's it doing?' he had descended about 1500 ft below the lowest altitude over portl intersection..11000 ft..and then quickly climbed back up to 11000 ft. ATC did not mention anything nor was any request made for us to contact anyone when on the ground.this vertical excursion was due to the fact that the PF had the autopilot in vs mode to control descent rate and should have had it in VNAV mode to track the tmbrs descent profile properly. The PF's lack of attention to the vertical profile and my lack of monitoring for a couple of minutes caught us both by surprise.in future I will read all unfamiliar sids and stars carefully taking note of any unusual speed restrictions and will brief that before we start the procedure.also; this particular PF has surprised me in the past with other things similar to this when I have 'let my guard down'. Not to lay all blame on him but to remind myself that I must continue to be especially vigilant when flying with that crew member.

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Original NASA ASRS Text

Title: BD700 Flight Crew reported not detecting a 280 knot speed restriction on the TMBRS2 RNAV to PDX. Once pointed out they believed it did not apply since they were proceeding direct to a fix on the arrival but not actually on the arrival. The crossing restriction at PORTL was missed due to descending in V/S instead of VNAV and misinterpreting the chart.

Narrative: Descending via the TMBRS 2 RNAV arrival to PDX. I was the PM and we were cleared Direct to TMBRS intersection and to descend. About 30 miles prior to TMBRS ATC asked our speed. 320 kts. We were advised there is a 280 KIAS speed restriction but because we were cleared direct to TMBRS and not yet on a Descend Via clearance we did not think this speed restriction applied. Actually; the Speed Restriction note on the STAR is new to both the crew members. Usually a Ball Note or speed limiting procedure is noted near to the mapped routing or intersection but this Speed Restriction small box was to the side of the route...a new convention to both of us. I am still not clear that we needed to abide by this restriction as we were not cleared to descend via that arrival and; in fact; had not yet begun any portion of the arrival as we were still flying direct to a fix on the STAR; but the controller was agitated nonetheless. Then; just as we were recovering from that episode and I was saying it myself to focus and do not be distracted by the incident and pay attention so as not to make another error...we made another error. We were NOW cleared to descend via the TMBRS 2 arrival 'Landing West' and the FMS was programmed and all the database altitude and speed restrictions were confirmed with the chart. I then put my head down to work on another task and soon the PF let out a 'what's it doing?' He had descended about 1500 FT below the lowest altitude over PORTL intersection..11000 FT..and then quickly climbed back up to 11000 FT. ATC did not mention anything nor was any request made for us to contact anyone when on the ground.This vertical excursion was due to the fact that the PF had the autopilot in VS mode to control descent rate and should have had it in VNAV mode to track the TMBRS descent profile properly. The PF's lack of attention to the vertical profile and my lack of monitoring for a couple of minutes caught us both by surprise.In future I will read ALL unfamiliar SIDs and STARs carefully taking note of any unusual speed restrictions and will brief that before we start the procedure.Also; this particular PF has surprised me in the past with other things similar to this when I have 'let my guard down'. Not to lay all blame on him but to remind myself that I must continue to be especially vigilant when flying with that crew member.

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.