Medium Transport; Low Wing; 2 Turbojet Eng
Flight Crew Air Transport Pilot (ATP)
Confusion; Distraction
Deviation - Speed All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance; Flight Crew FLC complied w / Automation / Advisory; Flight Crew Returned To Clearance
Chart Or Publication; Airport; Procedure
We were cleared to descend via the HAWKZ3 RNAV landing north transition [Runway] 34L. Ahead of time I had briefed the arrival and approach. In addition; I carefully checked; against my iPad's Charts; all the fixes in the FMS for altitudes and speed restrictions. My First Officer; as well checked the same against the paper charts. We both missed the box indicating the transition from MACH number to 280 KTS. We were descending at 310 KTS when the SEA Center Controller asked us the speed. After she advised us that we had to be at 280 KTS; I slowed to 280 KTS. We were so surprised that we went back searching in the arrival chart where the 280 was. We were honestly convinced that the controller was making a mistake. It took us a few seconds before we saw the note and realized that she was right.Since the first time I flew into SEA (back in June 2013) I completely missed the general note even if since then I came back several times and I always checked every fix. (The other times we must have accidentally complied with the 280 KTS due to other reasons like weather/speed assigned ahead by ATC etc). By enlarging the electronic chart the note tends to disappear in the left corner.  I would have expected to see a number referring to the note in proximity of both arrival transitions (LMT/LKV) or that same note/box located next to the two transitions or better to the right of BTG VOR where we would have not missed it.I have certainly learned the lesson of looking over at the whole chart (whether it be electronic or paper) to make sure I don't miss an important note like that anymore. A chart design with that important note in a better place would have certainly helped.
An air carrier Captain and First Officer did not see the SEA HAWKZ 3 RNAV MACH number to 280 KTS speed transition note and were surprised by ATC's request that they slow. The SPEED RESTRICTION note is too far separated from its application.