Narrative:

LNAV departure deviation. First officer's leg. On departure out of las, LNAV was engaged at 400 ft, and the first officer started a left turn at approximately 1000 ft. I asked 'where are we going?' he said 'I'm following the LNAV.' I asked what departure we were given. We had checked and briefed in accordance with company procedure at the gate, but I wanted to be sure. He said aaces. I directed him to return to runway heading to 4.7 DME. When I checked the FMC, the departure was not in. The first fix was aaces, which is where the LNAV was trying to take us. At 4.7 DME, we started a left turn, and at that time, departure control gave us vectors. We reintercepted the LNAV when given direct chipz by departure. At some point after verifying the route in the FMC at the gate, a keystroke error occurred or the FMC dropped the departure out. We do not check this during the pretkof checklist, and there is no backup. I have never been comfortable not having the radials, vors or DME as a backup on the LNAV departure or arrs. Although I do not think this 'south' turn after takeoff was a problem for ATC, it did probably put us a little south of course between the end of the runway and the first fix at 4.7 DME. Please give us a backup. Put the VOR frequency radials and DME's on the LNAV plates. Callback conversation with reporter revealed the following information: the concern is that there is no backup for the RNAV routing from any other navigation system. Until vectors could be given by ATC, dead reckoning was used to fly the approximately route. The first officer was relatively new, and may have miskeyed the FMS, and the missing fixes on the route were not caught before it was executed. The SOP includes a check of the legs page for accuracy, but for takeoff, the takeoff reference page is displayed precluding any chance to catch errors just prior to takeoff. Supplemental information from acn 572583: after takeoff at 400 ft, LNAV was engaged for aaces 2 LNAV departure. At about 1000 ft AGL, the flight director was commanding a left turn. I was hand flying and gently started turning into the flight director. The captain asked me where I was going. I told him I was following the LNAV. He then told me to turn back towards 250 degree heading, which I did, and kept the heading to 4.7 DME from las VOR. He also told departure that we were correcting to the right. After the turn, we were given heading 180 degrees expect hitme, then we were cleared left direct chipz. The captain pulled up the legs page on the FMC and entered chipz, and told me that some of the fixes were missing on the aaces 2 departure, and he corrected the departure in the FMC. From that point on, the flight was uneventful. In cruise, we talked about the deviation and concluded that during the pretkof checklist, when I activated the flight plan, the FMC lost the information on the departure fixes, and there was no way to back up the RNAV departure as no VOR radials were published for the departure. We should have rechked the flight plan in the FMC after it was activated, and the runway was selected.

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Original NASA ASRS Text

Title: A COURSE DEV JUST AFTER TKOF FROM LAS, NV. THE AACES RNAV 2 DEP HAD BEEN PLANNED, BUT ALL THE REQUIRED FIXES WERE NOT THERE.

Narrative: LNAV DEP DEV. FO'S LEG. ON DEP OUT OF LAS, LNAV WAS ENGAGED AT 400 FT, AND THE FO STARTED A L TURN AT APPROX 1000 FT. I ASKED 'WHERE ARE WE GOING?' HE SAID 'I'M FOLLOWING THE LNAV.' I ASKED WHAT DEP WE WERE GIVEN. WE HAD CHKED AND BRIEFED IN ACCORDANCE WITH COMPANY PROC AT THE GATE, BUT I WANTED TO BE SURE. HE SAID AACES. I DIRECTED HIM TO RETURN TO RWY HDG TO 4.7 DME. WHEN I CHKED THE FMC, THE DEP WAS NOT IN. THE FIRST FIX WAS AACES, WHICH IS WHERE THE LNAV WAS TRYING TO TAKE US. AT 4.7 DME, WE STARTED A L TURN, AND AT THAT TIME, DEP CTL GAVE US VECTORS. WE REINTERCEPTED THE LNAV WHEN GIVEN DIRECT CHIPZ BY DEP. AT SOME POINT AFTER VERIFYING THE RTE IN THE FMC AT THE GATE, A KEYSTROKE ERROR OCCURRED OR THE FMC DROPPED THE DEP OUT. WE DO NOT CHK THIS DURING THE PRETKOF CHKLIST, AND THERE IS NO BACKUP. I HAVE NEVER BEEN COMFORTABLE NOT HAVING THE RADIALS, VORS OR DME AS A BACKUP ON THE LNAV DEP OR ARRS. ALTHOUGH I DO NOT THINK THIS 'S' TURN AFTER TKOF WAS A PROB FOR ATC, IT DID PROBABLY PUT US A LITTLE S OF COURSE BTWN THE END OF THE RWY AND THE FIRST FIX AT 4.7 DME. PLEASE GIVE US A BACKUP. PUT THE VOR FREQ RADIALS AND DME'S ON THE LNAV PLATES. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE CONCERN IS THAT THERE IS NO BACKUP FOR THE RNAV ROUTING FROM ANY OTHER NAV SYS. UNTIL VECTORS COULD BE GIVEN BY ATC, DEAD RECKONING WAS USED TO FLY THE APPROX RTE. THE FO WAS RELATIVELY NEW, AND MAY HAVE MISKEYED THE FMS, AND THE MISSING FIXES ON THE RTE WERE NOT CAUGHT BEFORE IT WAS EXECUTED. THE SOP INCLUDES A CHK OF THE LEGS PAGE FOR ACCURACY, BUT FOR TKOF, THE TKOF REF PAGE IS DISPLAYED PRECLUDING ANY CHANCE TO CATCH ERRORS JUST PRIOR TO TKOF. SUPPLEMENTAL INFO FROM ACN 572583: AFTER TKOF AT 400 FT, LNAV WAS ENGAGED FOR AACES 2 LNAV DEP. AT ABOUT 1000 FT AGL, THE FLT DIRECTOR WAS COMMANDING A L TURN. I WAS HAND FLYING AND GENTLY STARTED TURNING INTO THE FLT DIRECTOR. THE CAPT ASKED ME WHERE I WAS GOING. I TOLD HIM I WAS FOLLOWING THE LNAV. HE THEN TOLD ME TO TURN BACK TOWARDS 250 DEG HDG, WHICH I DID, AND KEPT THE HDG TO 4.7 DME FROM LAS VOR. HE ALSO TOLD DEP THAT WE WERE CORRECTING TO THE R. AFTER THE TURN, WE WERE GIVEN HDG 180 DEGS EXPECT HITME, THEN WE WERE CLRED L DIRECT CHIPZ. THE CAPT PULLED UP THE LEGS PAGE ON THE FMC AND ENTERED CHIPZ, AND TOLD ME THAT SOME OF THE FIXES WERE MISSING ON THE AACES 2 DEP, AND HE CORRECTED THE DEP IN THE FMC. FROM THAT POINT ON, THE FLT WAS UNEVENTFUL. IN CRUISE, WE TALKED ABOUT THE DEV AND CONCLUDED THAT DURING THE PRETKOF CHKLIST, WHEN I ACTIVATED THE FLT PLAN, THE FMC LOST THE INFO ON THE DEP FIXES, AND THERE WAS NO WAY TO BACK UP THE RNAV DEP AS NO VOR RADIALS WERE PUBLISHED FOR THE DEP. WE SHOULD HAVE RECHKED THE FLT PLAN IN THE FMC AFTER IT WAS ACTIVATED, AND THE RWY WAS SELECTED.

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.