Narrative:

While in cruise, flying from the west to east coast, the first officer left the flight deck to use the restroom. I now became the PF during his absence. Shortly thereafter ATC cleared us direct to rod VOR. I selected rod on the FMC to go direct. Shortly thereafter the first officer returned to the flight deck. ATC then again asked us to go direct to rod, which was still 10 degrees to our left. At this time I realized that the mode control panel was still in the heading mode from a prior clearance. I then engaged the LNAV function on the mode control panel and we continued on direct to rod. This was a situation where I had allowed myself to get out of the loop as a PNF. When I suddenly had to transition to the PF, I forgot which mode the FMC was in. Additionally, now I didn't have the benefit of my first officer as a backup. Fortunately, our deviation was minor and presented no conflict with other aircraft, but the potential was certainly there. The moral to my story is 'check and rechk' with every clearance, especially when by yourself. Additionally, stay in the loop with the PF/PNF at all times. While it's easy to become complacent when fling long-haul flts, we have to keep ourselves aware of every and any change on the flight deck, in all phases of flight.

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Original NASA ASRS Text

Title: HEADING DEV BY B737-300 NEAR ROD.

Narrative: WHILE IN CRUISE, FLYING FROM THE W TO E COAST, THE FO LEFT THE FLT DECK TO USE THE RESTROOM. I NOW BECAME THE PF DURING HIS ABSENCE. SHORTLY THEREAFTER ATC CLRED US DIRECT TO ROD VOR. I SELECTED ROD ON THE FMC TO GO DIRECT. SHORTLY THEREAFTER THE FO RETURNED TO THE FLT DECK. ATC THEN AGAIN ASKED US TO GO DIRECT TO ROD, WHICH WAS STILL 10 DEGS TO OUR L. AT THIS TIME I REALIZED THAT THE MODE CTL PANEL WAS STILL IN THE HEADING MODE FROM A PRIOR CLRNC. I THEN ENGAGED THE LNAV FUNCTION ON THE MODE CTL PANEL AND WE CONTINUED ON DIRECT TO ROD. THIS WAS A SIT WHERE I HAD ALLOWED MYSELF TO GET OUT OF THE LOOP AS A PNF. WHEN I SUDDENLY HAD TO TRANSITION TO THE PF, I FORGOT WHICH MODE THE FMC WAS IN. ADDITIONALLY, NOW I DIDN'T HAVE THE BENEFIT OF MY FO AS A BACKUP. FORTUNATELY, OUR DEV WAS MINOR AND PRESENTED NO CONFLICT WITH OTHER ACFT, BUT THE POTENTIAL WAS CERTAINLY THERE. THE MORAL TO MY STORY IS 'CHK AND RECHK' WITH EVERY CLRNC, ESPECIALLY WHEN BY YOURSELF. ADDITIONALLY, STAY IN THE LOOP WITH THE PF/PNF AT ALL TIMES. WHILE IT'S EASY TO BECOME COMPLACENT WHEN FLING LONG-HAUL FLTS, WE HAVE TO KEEP OURSELVES AWARE OF EVERY AND ANY CHANGE ON THE FLT DECK, IN ALL PHASES OF FLT.

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.