Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 8; Flight Crew Total 21000; Flight Crew Type 250
Communication Breakdown; Confusion; Training / Qualification
Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued New Clearance
Human Factors
After filing IFR; I got an email (Foreflight) stating 'Expected Route Received' of 'BFI TAOMA J5 SUMMA J54 BKE BYI BEARR5 ZZZ. BFI clearance delivery gave me a verbal clearance of NRVNA1 TAOMA fly 135; climb via SID. The SID has a climb limit of 2;000 feet. Tower cleared me for takeoff and (I believe)135 heading. After takeoff; I checked in with Seattle Departure and a few seconds later; they asked me what my heading was. I replied 135 then direct NRVNA which is what the SID says. They asked me again and now I was SURE I was not doing what I was supposed to be doing. They gave me a 30deg LEFT turn followed shortly by a climb; so I believe I flew farther to the west than what they expected of me. I am still confused by what I would term a sort of 'hybrid' clearance. Was I cleared to fly the NRVNA SID or was I supposed to maintain 135 deg heading until further notice. It was the combination of 'fly 135' and 'climb via SID' that seemed contradictory. I should have been more forceful in querying the controller; but the freq was very busy. A simple solution; in my opinion; would have been for Tower to say 'Fly 135; climb and maintain 2;000 feet; cleared for takeoff'. Then it would have been clear to me that the NRVNA SID was not expected right after takeoff.
Pilot reported a heading deviation after takeoff that was caused by confusing pre-takeoff clearance instructions.