HEADING DEVIATION.

Narrative

FLT DEPARTED RWY 26R AT ONTARIO ARPT AT XXXX FLEW PRADO ONE DEP. LEFT TURN IMMEDIATELY AFTER TKOF DIRECT TO PDZ VOR. WE STARTED A LEFT TURN DIRECT TO PDZ VOR; BUT VOR NEEDLE WAS FLUCTUATING ABOUT 30 DEG LEFT AND RIGHT. STOPPED TURN AND ROLLED OUT TO FIGURE OUT WHERE PDZ WAS. CREW GOT BUSY DURING THIS TIME WITH NORMAL PROC; IE; GEAR RETRACTION; FLAP RETRACTION; SLAT RETRACTION; TFC WATCH. THIS DEP IS A VERY QUICK ONE. EVERYTHING HAPPENS VERY QUICKLY. THE F/O HAD HIS NAV RADIO TUNED TO SLI. WHEN CAPT'S NEEDLE FINALLY SETTLED DOWN; IT WAS POINTING TO PDZ; ABOUT 50 DEG TO THE LEFT OF OUR HDG. THE OTHER NEEDLE; HOWEVER; WAS STRAIGHT AHEAD. WE INADVERTENTLY FLEW TOWARD THE WRONG NEEDLE WHICH WAS POINTING TOWARD SLI. WE DID REALIZE AFTER A FEW SEC WHAT WE HAD DONE; AND IMMEDIATELY TURNED LEFT BACK TOWARDS PDZ. WE NEVER GOT BACK ON COURSE. WE PASSED 3 MI W OF PDZ VOR. THE REASON THIS HAPPENED WAS AT FIRST THE FLUCTUATION OF OUR COURSE NEEDLE. HOWEVER; IT LOCKED ON COURSE SHORTLY THEREAFTER AND WE DID NOT PICK THIS UP AS SOON AS WE SHOULD HAVE. GETTING DISTRACTED IN THE COCKPIT WAS MAIN CAUSE FOR THIS DEVIATION. WE SHOULD HAVE NOTICED THE COURSE DEVIATION SOONER. WE TALKED TO THE SUPVR ON DUTY BY PHONE AND THEY TOLD US THERE WAS NO CONFLICT AND THIS WAS NO PROB. CLOSER ATTN TO OUR NAV INSTRUMENTS PROBABLY WOULD HAVE AVOIDED THIS COURSE DEV.