CE560 FLIGHT CREW EXPERIENCES A COURSE DEVIATION ON THE BANYO FOUR SID FROM SDL; AZ.

Narrative

DEPARTING RWY 21 AT SDL; OUR CLRNC WAS THE BANYO4 DEP. WE HAD THE FMS SET UP AND THE FLT DIRECTOR FOLLOWING THE DEP ON INITIAL CLB ON THE 300 DEG HDG AS PUBLISHED. WE EVEN MADE SURE BEFORE DEP TO DISPLAY THE BEARING POINTER NEEDLE OF VOR 1 AND MADE SURE THAT BOTH OF US HAD PXR DISPLAYED IN OUR RESPECTIVE NAV FREQS. THE AUTOPLT WAS ON AS I WANTED TO BE ABLE TO SCAN FOR WX ON THE RADAR AS THERE WERE QUITE A FEW BUILDUPS IN THE AREA DURING OUR APCH 1 HR EARLIER; AND HVY RAIN SHOWERS WERE DURING OUR TURNAROUND TIME ON THE GND. WE WERE LEVELING AT 5000 FT AS ASSIGNED AND ATC GAVE US A R TURN HDG OF 340 DEGS. I BEGAN SCANNING THE RADAR FOR PRECIP IN THE VICINITY. AFTER A VERY SHORT WHILE; ATC TURNED US BACK (AND I AM NOT SURE IF THEY GAVE US ANOTHER CLB TO ADD TO THE WORKLOAD) TO A HDG OF 270 DEGS TO INTERCEPT THE 321 DEG RADIAL FROM PXR. IN TALKING ABOUT IT TOGETHER; WE BOTH (THE FLT CREW) WERE IN AGREEMENT THAT WE BOTH THOUGHT HE SAID THE 321 DEG RADIAL TO BANYO BUT NOT SURE IF HE ACTUALLY DID OR NOT. THE LNAV WAS ARMED ON THE FLT DIRECTOR BECAUSE I DID NOT WANT TO OVERSHOOT THE COURSE BECAUSE I NOTICED THAT THE COURSE WAS ALIVE. I IMMEDIATELY ASKED THE PNF FO IF THE 321 DEG RADIAL WENT TO BANYO; BECAUSE THE FMS COURSE WAS SHOWING 336 DEGS. AS THE FO PNF LOOKED DOWN AT THE PLATE TO CONFIRM; THE ACFT SIMULTANEOUSLY BEGAN THE TURN TO 336 DEGS ON THE LNAV COURSE. HE WAS LOOKING AT THE PLATE FOR ONLY A SECOND TO TRY TO CONFIRM WHAT I WAS SEEING AND DID NOT DELAY IN HIS RESPONSE BUT EVERYTHING WAS HAPPENING QUICKLY. HE STARTED TO REPLY LESS THAN A SECOND LATER WHILE THE ACFT SIMULTANEOUSLY ROLLED WINGS LEVEL. I IMMEDIATELY NOTICED THAT THERE TFC ON THE TCAS ABOVE US AND I STARTED TO SAY SOMETHING BUT ATC INTERRUPTED AS WE SIMULTANEOUSLY ROLLED WINGS LEVEL AND TOLD US TO MAKE AN IMMEDIATE TURN TO HDG 210 DEGS; TURN IMMEDIATELY TO HDG 210 DEGS. I DISCONNECTED THE AUTOPLT AND HAND FLEW THE TURN TO 210 DEGS AND THEN THE SUBSEQUENT VECTOR OF 240 DEGS. I RE-ENGAGED THE AUTOPLT AT THIS TIME AND THERE WAS A BREAK WHERE THINGS WERE NOT HAPPENING ONE RIGHT AFTER ANOTHER; SO I HAD SOME TIME TO LOOK BACK OVER THE BANYO DEP AND REALIZED WHAT HAPPENED. WE DISCUSSED IT BTWN THE TWO OF US AND THE REST OF THE FLT PROCEEDED WITHOUT INCIDENT. I BELIEVE WHAT CONTRIBUTED TO THE EVENT WAS THE HIGH WORKLOAD ON DEP COMBINED WITH THE RELIANCE OF AUTOMATION (FMS) WHEN MY CONCERN WAS WX AVOIDANCE. IN HINDSIGHT; I REALIZED THAT I DID NOT BRIEF THOROUGHLY THE RADIALS THAT DEFINED THE COURSE; BUT I ACTUALLY ONLY BRIEFED THE RADIAL TO BANYO AND THEN RADAR VECTORS TO THE INTXNS THAT DEFINED OUR COURSE. (CORRECTIVE ACTION: I WILL CHANGE MY BRIEFING TO INCLUDE GND BASED NAVAID RADIALS INSTEAD OF SOLELY FMS COURSES.) I NEVER BRIEFED THE RADIAL THAT DEFINED THE COURSE. MY BRIEF EMPHASIZED THE FACT THAT WE WERE BELOW CLASS B AIRSPACE; OUR INITIAL HDG TO INTERCEPT OUR COURSE WAS 300 DEGS; THE COURSE TO BANYO WAS THE 336 DEG RADIAL OFF OF PXR; EXPECT VECTORS ON COURSE TO ZEPER AND KARLO. I NEVER BRIEFED THAT ZEPER AND KARLO WERE ON THE 321 RADIAL FROM PXR.