Narrative:

Planning on a backcourse approach to runway 23 at clt, we had set up our ILS frequencys and front course heading as well as selecting backcourse 23 approach on our RNAV to use as a backup. In the RNAV system we have, the approach selected is on a menu of approach choices for various runways. They are preprogrammed and include several fixes listed on the approach plate. The problem began when we were turned inbound to intercept the final approach course inside the first fix on the RNAV preplanned approach package. From that point on, we received false distance readings from the RNAV display and by the time we realized the problem, we were too high to continue the approach. A missed approach was initiated and a subsequent approach was flown to landing with no further problems incurred.

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Original NASA ASRS Text

Title: FLC OF ACR MLG ACFT EXPERIENCED FALSE DISTANT READINGS DURING A PREPROGRAMMED RNAV BACK-COURSE APCH RESULTING IN A MAP.

Narrative: PLANNING ON A BACKCOURSE APCH TO RWY 23 AT CLT, WE HAD SET UP OUR ILS FREQS AND FRONT COURSE HDG AS WELL AS SELECTING BACKCOURSE 23 APCH ON OUR RNAV TO USE AS A BACKUP. IN THE RNAV SYS WE HAVE, THE APCH SELECTED IS ON A MENU OF APCH CHOICES FOR VARIOUS RWYS. THEY ARE PREPROGRAMMED AND INCLUDE SEVERAL FIXES LISTED ON THE APCH PLATE. THE PROBLEM BEGAN WHEN WE WERE TURNED INBOUND TO INTERCEPT THE FINAL APCH COURSE INSIDE THE FIRST FIX ON THE RNAV PREPLANNED APCH PACKAGE. FROM THAT POINT ON, WE RECEIVED FALSE DISTANCE READINGS FROM THE RNAV DISPLAY AND BY THE TIME WE REALIZED THE PROBLEM, WE WERE TOO HIGH TO CONTINUE THE APCH. A MISSED APCH WAS INITIATED AND A SUBSEQUENT APCH WAS FLOWN TO LNDG WITH NO FURTHER PROBLEMS INCURRED.

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.