Narrative:

Our clearance after takeoff was to fly runway heading to 1500 ft then turn left to 180 degrees magnetic (not sure of exact heading) and climb to 4000 ft. We were cleared for takeoff and immediately entered rain and turbulence. WX radar showed returns on all sides with purple doppler returns throughout. The captain and I were both observing WX radar and coast approach was very 'busy.' we remained on runway heading to 4000 when coast asked us if we had started our turn. At this point realizing our mistake I immediately turned to our assigned heading. I believe we missed making our assigned turn at 1500 due to heavy workload in cockpit at the time along with focusing our attention on radar for WX avoidance. Additionally, I had been used to hearing 'maintain runway heading for vectors' and when we received this particular clearance, the turn at 1500 was a trap that we fell into. Sometimes, I believe, when you get used to a 'pattern' and you get thrown a 'curve' it's easy to miss. In summary, or to recap, I think that 3 factors aided us in our mistake. Turbulence and WX caused us to focus more on radar screen than to flying the aircraft. High volume of communications in this phase of our flight helped add to overall 'stimulus' in cockpit. The turn at 1500 was a slight change in my mind from either 'maintain runway heading' or a turn immediately after takeoff that we are more normally accustomed to. The time to climb to 1500 gave us a chance to forget making our turn -- and we did.

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Original NASA ASRS Text

Title: FLC OF MLG MISSED TURN AT 1500 MSL PER SID WHILE DEPARTING LGB.

Narrative: OUR CLRNC AFTER TKOF WAS TO FLY RWY HDG TO 1500 FT THEN TURN L TO 180 DEGS MAGNETIC (NOT SURE OF EXACT HDG) AND CLB TO 4000 FT. WE WERE CLRED FOR TKOF AND IMMEDIATELY ENTERED RAIN AND TURB. WX RADAR SHOWED RETURNS ON ALL SIDES WITH PURPLE DOPPLER RETURNS THROUGHOUT. THE CAPT AND I WERE BOTH OBSERVING WX RADAR AND COAST APCH WAS VERY 'BUSY.' WE REMAINED ON RWY HDG TO 4000 WHEN COAST ASKED US IF WE HAD STARTED OUR TURN. AT THIS POINT REALIZING OUR MISTAKE I IMMEDIATELY TURNED TO OUR ASSIGNED HDG. I BELIEVE WE MISSED MAKING OUR ASSIGNED TURN AT 1500 DUE TO HVY WORKLOAD IN COCKPIT AT THE TIME ALONG WITH FOCUSING OUR ATTN ON RADAR FOR WX AVOIDANCE. ADDITIONALLY, I HAD BEEN USED TO HEARING 'MAINTAIN RWY HDG FOR VECTORS' AND WHEN WE RECEIVED THIS PARTICULAR CLRNC, THE TURN AT 1500 WAS A TRAP THAT WE FELL INTO. SOMETIMES, I BELIEVE, WHEN YOU GET USED TO A 'PATTERN' AND YOU GET THROWN A 'CURVE' IT'S EASY TO MISS. IN SUMMARY, OR TO RECAP, I THINK THAT 3 FACTORS AIDED US IN OUR MISTAKE. TURB AND WX CAUSED US TO FOCUS MORE ON RADAR SCREEN THAN TO FLYING THE ACFT. HIGH VOLUME OF COMS IN THIS PHASE OF OUR FLT HELPED ADD TO OVERALL 'STIMULUS' IN COCKPIT. THE TURN AT 1500 WAS A SLIGHT CHANGE IN MY MIND FROM EITHER 'MAINTAIN RWY HDG' OR A TURN IMMEDIATELY AFTER TKOF THAT WE ARE MORE NORMALLY ACCUSTOMED TO. THE TIME TO CLB TO 1500 GAVE US A CHANCE TO FORGET MAKING OUR TURN -- AND WE DID.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.