Narrative:

During darc only operations, aircraft X was en route from phx to oma on an assigned beacon code of XXXX. A shift change had occurred at XA30. At approximately XA45, I initiated a search of all aircraft that were unaccounted for. A search for aircraft X initially resulted in no full data block or limited data block being observed. The radar controller initiated a beacon code entry resulting in a full data block display of aircraft X approximately 20 mi west of lamar, co. The radar controller verified the position of aircraft X by asking the flight crew to identify, no data has been collected from either our darc tapes or adjacent ctrs (ZAB, ZKC) NAS radar data. Additionally no interviews have been conducted with any other controllers. The full data block when acquired indicated track control had been xferred. We reacquired track control at this time. The flight progress strip and computer entries suggest that this flight was entered correctly in the flight list and that at some time a data block, either full or limited, was observed by the previous crew. The xfer of track control would suggest that the aircraft had successfully handed off to the next sector prior to loss of radar data. This occurrence was an apparent failure of the darc system to track the transponder data of aircraft X. The darc tape in use was loaded on jul/xa/98. To our knowledge all other aircraft were tracked normally. A NAS action request was initiated on this incident.

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Original NASA ASRS Text

Title: ZDV ARTCC RADAR CTLR INITIATES ACTIONS TO LOCATE ACR FOUND IN HIS STRIP BAY. ZAB CTLR FINDS ACR IN HIS AIRSPACE AND EFFECTS KEYBOARD FUNCTIONS TO ACCEPT AND TAKE CTL OF DATA BLOCK. ZDV CTLR SUBMITS NAS DARC SYS RPT TO ASCERTAIN WHAT HAPPENED DURING DARC TRANSITION.

Narrative: DURING DARC ONLY OPS, ACFT X WAS ENRTE FROM PHX TO OMA ON AN ASSIGNED BEACON CODE OF XXXX. A SHIFT CHANGE HAD OCCURRED AT XA30. AT APPROX XA45, I INITIATED A SEARCH OF ALL ACFT THAT WERE UNACCOUNTED FOR. A SEARCH FOR ACFT X INITIALLY RESULTED IN NO FULL DATA BLOCK OR LIMITED DATA BLOCK BEING OBSERVED. THE RADAR CTLR INITIATED A BEACON CODE ENTRY RESULTING IN A FULL DATA BLOCK DISPLAY OF ACFT X APPROX 20 MI W OF LAMAR, CO. THE RADAR CTLR VERIFIED THE POS OF ACFT X BY ASKING THE FLC TO IDENT, NO DATA HAS BEEN COLLECTED FROM EITHER OUR DARC TAPES OR ADJACENT CTRS (ZAB, ZKC) NAS RADAR DATA. ADDITIONALLY NO INTERVIEWS HAVE BEEN CONDUCTED WITH ANY OTHER CTLRS. THE FULL DATA BLOCK WHEN ACQUIRED INDICATED TRACK CTL HAD BEEN XFERRED. WE REACQUIRED TRACK CTL AT THIS TIME. THE FLT PROGRESS STRIP AND COMPUTER ENTRIES SUGGEST THAT THIS FLT WAS ENTERED CORRECTLY IN THE FLT LIST AND THAT AT SOME TIME A DATA BLOCK, EITHER FULL OR LIMITED, WAS OBSERVED BY THE PREVIOUS CREW. THE XFER OF TRACK CTL WOULD SUGGEST THAT THE ACFT HAD SUCCESSFULLY HANDED OFF TO THE NEXT SECTOR PRIOR TO LOSS OF RADAR DATA. THIS OCCURRENCE WAS AN APPARENT FAILURE OF THE DARC SYS TO TRACK THE XPONDER DATA OF ACFT X. THE DARC TAPE IN USE WAS LOADED ON JUL/XA/98. TO OUR KNOWLEDGE ALL OTHER ACFT WERE TRACKED NORMALLY. A NAS ACTION REQUEST WAS INITIATED ON THIS INCIDENT.

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.