B737-800
Flight Crew Air Transport Pilot (ATP)
Training / Qualification; Situational Awareness; Communication Breakdown
Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued New Clearance; Flight Crew Became Reoriented; Flight Crew Returned To Clearance
Manuals; Human Factors
Departing SEA; we were flight planned the Mountain 6 SID. PDC had a 'Revised Segment' (-SEA J70 MLP KU15M). We mistook that for a change to the SEATL4 SID. We intercepted the 161 degree radial; and missed the turn to 070 degree. SEA Departure Control then cleared us direct to NORMY.
[Narrative #2 had no additional information.]
A B737 crew misread a 'Revised Segment' departing SEA and had a track deviation when they started flying the SEATL4 which was not on the PDC.