Flight Crew Air Transport Pilot (ATP)
Human-Machine Interface; Situational Awareness
Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance; Flight Crew Became Reoriented; Flight Crew Returned To Clearance
Human Factors
Prior to departure I loaded the FMS with the first fix on the PDC that was 'PUMKN.' I inadvertently entered the fix as 'PMPKN.' When told to go direct to 'PUMKN' we started to turn towards the wrong Pumpkin (hundreds of miles away in the wrong direction.) ATC noticed the deviation and gave us a vector towards the right Pumpkin. I entered the correct identifier and started tracking. ATC had no further comment. I think 'my' pumpkin spelling seemed more logical to me. I somehow changed the spelling from the PDC because I was not attentive to the PDC spelling. Be more attentive to similar sounding fixes.
After being cleared direct to 'PUMKN' crew incorrectly typed 'PMPKN' resulting in aircraft track error.