Narrative:

Captain inadvertently created a course reversal between 2 waypoints along a straight course line. Although I checked my programming I missed the error. The course reversal artificially added distance to top of descent to cross 15 NM north of balance at 12000 ft. Consequently, I started down late with controller prompting, fessed up my error, and was vectored for descent. Curiously, I was xchking my descent versus the raw data and everything seemed ok. I was well within the parameters for a normal descent (from 20000 ft) to lose 8000 ft of altitude. I calculated a 3 to 1 descent profile and figured I'd need 24 NM to descend to 12000 ft. I couldn't understand initially why there was a problem. The raw data backed up the erroneous FMS computed touchdown point. Then, I realized I had made 2 errors simultaneously. I had just changed to dca VOR. I was checking my distance to destination and unknowingly neglected to retune balance. When I realized the controller was correct I felt a momentary sense of confusion. I knew I had made an error but it took a while to figure what I'd done. I'd made 2 concurrent errors.

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Original NASA ASRS Text

Title: FLC OF MLG MISSES XING RESTR DUE TO PROGRAMMING A COURSE REVERSAL ERROR.

Narrative: CAPT INADVERTENTLY CREATED A COURSE REVERSAL BTWN 2 WAYPOINTS ALONG A STRAIGHT COURSE LINE. ALTHOUGH I CHKED MY PROGRAMMING I MISSED THE ERROR. THE COURSE REVERSAL ARTIFICIALLY ADDED DISTANCE TO TOP OF DSCNT TO CROSS 15 NM N OF BAL AT 12000 FT. CONSEQUENTLY, I STARTED DOWN LATE WITH CTLR PROMPTING, FESSED UP MY ERROR, AND WAS VECTORED FOR DSCNT. CURIOUSLY, I WAS XCHKING MY DSCNT VERSUS THE RAW DATA AND EVERYTHING SEEMED OK. I WAS WELL WITHIN THE PARAMETERS FOR A NORMAL DSCNT (FROM 20000 FT) TO LOSE 8000 FT OF ALT. I CALCULATED A 3 TO 1 DSCNT PROFILE AND FIGURED I'D NEED 24 NM TO DSND TO 12000 FT. I COULDN'T UNDERSTAND INITIALLY WHY THERE WAS A PROB. THE RAW DATA BACKED UP THE ERRONEOUS FMS COMPUTED TOUCHDOWN POINT. THEN, I REALIZED I HAD MADE 2 ERRORS SIMULTANEOUSLY. I HAD JUST CHANGED TO DCA VOR. I WAS CHKING MY DISTANCE TO DEST AND UNKNOWINGLY NEGLECTED TO RETUNE BAL. WHEN I REALIZED THE CTLR WAS CORRECT I FELT A MOMENTARY SENSE OF CONFUSION. I KNEW I HAD MADE AN ERROR BUT IT TOOK A WHILE TO FIGURE WHAT I'D DONE. I'D MADE 2 CONCURRENT ERRORS.

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.