Narrative:

Aircraft was level at FL410 when ATC asked if we were deviating from course. I increased the scale of the map and noticed that we were off course by approximately 2.5 NM and that the aircraft was in heading mode instead of LNAV. The pm let ATC know we were intercepting back on course and that's what we did. I was the PF and we initially climbed out from elp on heading mode up to about FL230 and then were given 'direct peq and then on course.' I thought I had selected the LNAV mode but can only guess that I either didn't select it or it didn't take when I selected the LNAV button. In either case; I should have cross checked the scoreboard to make sure LNAV was selected. I failed to notice if we were off course because the first heading we were given by ATC sent us very close to the peq VOR and my map scale was selected to the 160 NM scale. It could have been prevented by simply crossing checking your actions. Instead of just selecting the LNAV button and seeing the light illuminate; the PF should check the 'scoreboard' to make sure the green LNAV mode is selected as well.supplemental information from acn 707807: on frequency handoff; I asked if there were any problems; the controller indicated there were none; but that ZFW's airspace was close by to the north and a correction was needed. How did this happen? We are both experienced and disciplined pilots; and work well together. We are both aware of the correct LNAV course intercept procedures; and are aware of the duties of the PF and PNF in this regard. I watched the PF make the move to engage LNAV out of the heading mode but did not notice the button failed to engage the system. It had been an eventful start to the day earlier at elp with two mels; one of which had not been listed on the release; requiring a phone call to maintenance and dispatch; then a loadsheet error; followed by a last minute runway change due to shifting winds. Finally airborne; we were settling down to what looked like a fairly benign leg. I believe a measure of complacency set in. I accept responsibility for not properly cross checking the navigation actions of the PF.

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Original NASA ASRS Text

Title: A B737-700 FLT CREW FAILED TO ENSURE LNAV ENGAGED PROPERLY AND MISSED A RTE FIX IN THE HDG MODE.

Narrative: ACFT WAS LEVEL AT FL410 WHEN ATC ASKED IF WE WERE DEVIATING FROM COURSE. I INCREASED THE SCALE OF THE MAP AND NOTICED THAT WE WERE OFF COURSE BY APPROX 2.5 NM AND THAT THE ACFT WAS IN HDG MODE INSTEAD OF LNAV. THE PM LET ATC KNOW WE WERE INTERCEPTING BACK ON COURSE AND THAT'S WHAT WE DID. I WAS THE PF AND WE INITIALLY CLBED OUT FROM ELP ON HDG MODE UP TO ABOUT FL230 AND THEN WERE GIVEN 'DIRECT PEQ AND THEN ON COURSE.' I THOUGHT I HAD SELECTED THE LNAV MODE BUT CAN ONLY GUESS THAT I EITHER DIDN'T SELECT IT OR IT DIDN'T TAKE WHEN I SELECTED THE LNAV BUTTON. IN EITHER CASE; I SHOULD HAVE CROSS CHKED THE SCOREBOARD TO MAKE SURE LNAV WAS SELECTED. I FAILED TO NOTICE IF WE WERE OFF COURSE BECAUSE THE FIRST HDG WE WERE GIVEN BY ATC SENT US VERY CLOSE TO THE PEQ VOR AND MY MAP SCALE WAS SELECTED TO THE 160 NM SCALE. IT COULD HAVE BEEN PREVENTED BY SIMPLY CROSSING CHKING YOUR ACTIONS. INSTEAD OF JUST SELECTING THE LNAV BUTTON AND SEEING THE LIGHT ILLUMINATE; THE PF SHOULD CHK THE 'SCOREBOARD' TO MAKE SURE THE GREEN LNAV MODE IS SELECTED AS WELL.SUPPLEMENTAL INFO FROM ACN 707807: ON FREQ HANDOFF; I ASKED IF THERE WERE ANY PROBS; THE CTLR INDICATED THERE WERE NONE; BUT THAT ZFW'S AIRSPACE WAS CLOSE BY TO THE N AND A CORRECTION WAS NEEDED. HOW DID THIS HAPPEN? WE ARE BOTH EXPERIENCED AND DISCIPLINED PLTS; AND WORK WELL TOGETHER. WE ARE BOTH AWARE OF THE CORRECT LNAV COURSE INTERCEPT PROCS; AND ARE AWARE OF THE DUTIES OF THE PF AND PNF IN THIS REGARD. I WATCHED THE PF MAKE THE MOVE TO ENGAGE LNAV OUT OF THE HDG MODE BUT DID NOT NOTICE THE BUTTON FAILED TO ENGAGE THE SYSTEM. IT HAD BEEN AN EVENTFUL START TO THE DAY EARLIER AT ELP WITH TWO MELS; ONE OF WHICH HAD NOT BEEN LISTED ON THE RELEASE; REQUIRING A PHONE CALL TO MAINT AND DISPATCH; THEN A LOADSHEET ERROR; FOLLOWED BY A LAST MINUTE RWY CHANGE DUE TO SHIFTING WINDS. FINALLY AIRBORNE; WE WERE SETTLING DOWN TO WHAT LOOKED LIKE A FAIRLY BENIGN LEG. I BELIEVE A MEASURE OF COMPLACENCY SET IN. I ACCEPT RESPONSIBILITY FOR NOT PROPERLY CROSS CHKING THE NAVIGATION ACTIONS OF THE PF.

Data retrieved from NASA's ASRS site as of January 2009 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.