Narrative:

I was flying the dryheat 2 departure out of phx to tul. The MCP was on autoplt 'a' with LNAV selected. The HSI select switch was on 'navigation.' the airplane was cleared direct to bayta intersection then the dryheat 2 departure. The LNAV took us to bayta, then chopr, then gilaa, then adyan just like it was supposed to do. Then it flew the 055 degree heading as depicted on the SID. It continued on this heading to dryht. Our clearance from phx clearance delivery had us cleared after dryht, J74, corona, which was programmed into the FMC. At dryht, the aircraft did not turn on course for J74. We subsequently went north of course a few mi before I caught it, figured it out and corrected back. We advised ZAB and the controller did not seem too concerned. He subsequently had us roll out on a 075 degree heading for traffic and shortly cleared us direct to irw airport. Also while flying the 055 degree toward dryht on the SID we never receiver a vector for dryht from ZAB. What I learned from this is that the FMC might not make the turn when you expect it to, so this will have to be monitored extremely close. If I had to do it over again, I would have questioned ZAB for route clearance while on the 055 degree heading on the SID. I am still researching why the aircraft did not turn down J74 after passing dryht.

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Original NASA ASRS Text

Title: A B737-300 CREW USING LNAV NOTES THAT THE ACFT DID NOT TURN AS EXPECTED AT THE DRYHT INTXN ON THE DRYHEAT 2 DEP OUT OF PHX, AZ.

Narrative: I WAS FLYING THE DRYHEAT 2 DEP OUT OF PHX TO TUL. THE MCP WAS ON AUTOPLT 'A' WITH LNAV SELECTED. THE HSI SELECT SWITCH WAS ON 'NAV.' THE AIRPLANE WAS CLRED DIRECT TO BAYTA INTXN THEN THE DRYHEAT 2 DEP. THE LNAV TOOK US TO BAYTA, THEN CHOPR, THEN GILAA, THEN ADYAN JUST LIKE IT WAS SUPPOSED TO DO. THEN IT FLEW THE 055 DEG HDG AS DEPICTED ON THE SID. IT CONTINUED ON THIS HDG TO DRYHT. OUR CLRNC FROM PHX CLRNC DELIVERY HAD US CLRED AFTER DRYHT, J74, CORONA, WHICH WAS PROGRAMMED INTO THE FMC. AT DRYHT, THE ACFT DID NOT TURN ON COURSE FOR J74. WE SUBSEQUENTLY WENT N OF COURSE A FEW MI BEFORE I CAUGHT IT, FIGURED IT OUT AND CORRECTED BACK. WE ADVISED ZAB AND THE CTLR DID NOT SEEM TOO CONCERNED. HE SUBSEQUENTLY HAD US ROLL OUT ON A 075 DEG HDG FOR TFC AND SHORTLY CLRED US DIRECT TO IRW ARPT. ALSO WHILE FLYING THE 055 DEG TOWARD DRYHT ON THE SID WE NEVER RECEIVER A VECTOR FOR DRYHT FROM ZAB. WHAT I LEARNED FROM THIS IS THAT THE FMC MIGHT NOT MAKE THE TURN WHEN YOU EXPECT IT TO, SO THIS WILL HAVE TO BE MONITORED EXTREMELY CLOSE. IF I HAD TO DO IT OVER AGAIN, I WOULD HAVE QUESTIONED ZAB FOR RTE CLRNC WHILE ON THE 055 DEG HDG ON THE SID. I AM STILL RESEARCHING WHY THE ACFT DID NOT TURN DOWN J74 AFTER PASSING DRYHT.

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.