Narrative:

I remember the controller stating, 'turn right 120 degrees, vectors to thermal' and both the first officer and myself (this was initial IOE for first officer on the so panel for last 3 yrs). A minute later, thought the controller said 'proceed to thermal when able.' at the same time of this turn/climb, a rogue screen appeared on the FMC legs page which diverted our attention. It was relevant because the first officer was trying to select the 'legs' page so he could engage the LNAV computer to proceed direct to thermal. When the first officer successfully selected the LNAV direct to thermal, the controller asked our heading. When we told him '095 degrees' he stated we were cleared heading 120 degrees. We both thought we had been cleared direct to thermal. The first officer was engrossed in completing the turn to thermal after questioning the appearance (uncommanded) of an unusual technical visual screen on his side. Shortly thereafter, the controller cleared us again direct to thermal. If we misinterpreted his instructions, it was because of the newness (first flight series) of the first officer in the copilot's seat and mine for not listening intently enough and not slowing down the first officer's nimble fingers on the FMC. No other aircraft were sighted during this period in VMC.

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Original NASA ASRS Text

Title: FLC PROCEEDED DIRECT, INSTEAD OF MAINTAINING ASSIGNED HDG.

Narrative: I REMEMBER THE CTLR STATING, 'TURN R 120 DEGS, VECTORS TO THERMAL' AND BOTH THE FO AND MYSELF (THIS WAS INITIAL IOE FOR FO ON THE SO PANEL FOR LAST 3 YRS). A MINUTE LATER, THOUGHT THE CTLR SAID 'PROCEED TO THERMAL WHEN ABLE.' AT THE SAME TIME OF THIS TURN/CLB, A ROGUE SCREEN APPEARED ON THE FMC LEGS PAGE WHICH DIVERTED OUR ATTN. IT WAS RELEVANT BECAUSE THE FO WAS TRYING TO SELECT THE 'LEGS' PAGE SO HE COULD ENGAGE THE LNAV COMPUTER TO PROCEED DIRECT TO THERMAL. WHEN THE FO SUCCESSFULLY SELECTED THE LNAV DIRECT TO THERMAL, THE CTLR ASKED OUR HDG. WHEN WE TOLD HIM '095 DEGS' HE STATED WE WERE CLRED HDG 120 DEGS. WE BOTH THOUGHT WE HAD BEEN CLRED DIRECT TO THERMAL. THE FO WAS ENGROSSED IN COMPLETING THE TURN TO THERMAL AFTER QUESTIONING THE APPEARANCE (UNCOMMANDED) OF AN UNUSUAL TECHNICAL VISUAL SCREEN ON HIS SIDE. SHORTLY THEREAFTER, THE CTLR CLRED US AGAIN DIRECT TO THERMAL. IF WE MISINTERPRETED HIS INSTRUCTIONS, IT WAS BECAUSE OF THE NEWNESS (FIRST FLT SERIES) OF THE FO IN THE COPLT'S SEAT AND MINE FOR NOT LISTENING INTENTLY ENOUGH AND NOT SLOWING DOWN THE FO'S NIMBLE FINGERS ON THE FMC. NO OTHER ACFT WERE SIGHTED DURING THIS PERIOD IN VMC.

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.