Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 50; Flight Crew Total 8450; Flight Crew Type 800
Communication Breakdown; Situational Awareness
Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued New Clearance; Flight Crew Became Reoriented; Flight Crew Returned To Clearance
Human Factors
Copied clearance prior to departure [from APC] was 'MERLO1 then Cleared as Filed'. That filed route was SAC.SWR. During climb; ATC had previously issued vector heading 030 followed by 'Cleared direct Truck'. Because TRUCK did not appear in our FMS flight plan; I instructed PNF to enter TRK in FMS and temporarily go direct as I assumed there was a TRK VOR located near the airport TRK. The FMS recognized the TRK WPT and proceeded in what seemed a reasonable direction. The controller soon after asked if we were headed direct TRUCK and we responded 'yes'. He then confirmed the spelling of the intended WPT as 'TRUCK' (not TRK). We requested a vector until we got the WPT sorted out. The controller issued a 'turn right heading 270.' We then had corrected the FMS WPT to TRUCK and advised and were cleared direct.A mistake on my part was assuming WPT spelling and not verifying w/ ATC when they issued something that was not in our flight plan. This is also the second time that our departure clearance from APC has been different or in error. Short of requesting a full route clearance; there isn't anyway to know that what is being issued as '..then cleared as filed' matches what was actually filed.
BE30 Captain reported a track deviation after departing APC when he was cleared to TRUCK; but navigated toward TRK.