Medium Large Transport; Low Wing; 2 Turbojet Eng
Flight Crew Last 90 Days 264
Confusion; Human-Machine Interface
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
Human Factors
While I was initializing the FMC; I left the runway blank due to the fact I was unsure of the active runway at that time.  Once I completed my cockpit preflight; and was verifying the route; I mistook NEVJO SUMMA (16L) on the LEGS page instead of NEZUG SUMMA (34R).  After takeoff; while switching to Departure and selecting LNAV; the FD started a right turn.  Pilot flying initially started the turn; but we quickly notice the error and started correcting back.  At that time ATC gave us a vector to join the SUMMA7.
Flight crew entered the wrong takeoff runway in the FMC resulting in an incorrect initial turn after takeoff.