Narrative:

The ARTS iie software cannot maintain the identity of targets when they merge, in many instances one or both data tags will drop from the local system completely (no longer displayed on the radar screen). These tags, once lost, can occasionally be re-acquired via the ARTS force fdio/ARTS keyboard function, but in many cases they cannot be re-acquired by any means. The problem lies in that the software is supposed to 'freeze' a data tag that it cannot track and never drop it from the radar display. Callback conversation with reporter revealed the following information: reporter stated that facility tracked targets will frequently drop from their tracked target status as the ARTS tags merge. Normally the dropped tag should default into the controller's 'CST' (coast) list. The reporter stated that when this happens, the controller can usually start, or force, tracking to the target. But in certain observed cases, the controller alleges that the dropped tag is not in his 'CST' list and can not be manually started. The data tag apparently has been dropped from the entire ARTS system. The controller advised that his facility has an ASR-8 installed system and that their aos support facility is san diego, ca. Reporter states that the facility aos specialist has advised that the anomaly has been identified as a 'disassociate problem message content.' apparently the facility ARTS iie software parameters are such that when two ARTS tags merge, and if the sum of their combined altitudes exceed the facility filter limits, the computer drops one or both tags as being out of system parameters, and therefore tracking is not required. Aos has advised that a fix is in the development in which facility altitude filter limit parameters will be changed from the low: 1000 ft to 100 ft, the maximum altitude: from 45000 ft to 99900 ft, and the radar radius changed from 55 NM to 57 NM. Site adaptation is expected within 30 days.

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Original NASA ASRS Text

Title: EVV TRACON ARTS IIE EXPERIENCING UNCOORDINATED UNPLANNED TRACK DROPS.

Narrative: THE ARTS IIE SOFTWARE CANNOT MAINTAIN THE IDENTITY OF TARGETS WHEN THEY MERGE, IN MANY INSTANCES ONE OR BOTH DATA TAGS WILL DROP FROM THE LOCAL SYSTEM COMPLETELY (NO LONGER DISPLAYED ON THE RADAR SCREEN). THESE TAGS, ONCE LOST, CAN OCCASIONALLY BE RE-ACQUIRED VIA THE ARTS FORCE FDIO/ARTS KEYBOARD FUNCTION, BUT IN MANY CASES THEY CANNOT BE RE-ACQUIRED BY ANY MEANS. THE PROB LIES IN THAT THE SOFTWARE IS SUPPOSED TO 'FREEZE' A DATA TAG THAT IT CANNOT TRACK AND NEVER DROP IT FROM THE RADAR DISPLAY. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT FAC TRACKED TARGETS WILL FREQUENTLY DROP FROM THEIR TRACKED TARGET STATUS AS THE ARTS TAGS MERGE. NORMALLY THE DROPPED TAG SHOULD DEFAULT INTO THE CTLR'S 'CST' (COAST) LIST. THE RPTR STATED THAT WHEN THIS HAPPENS, THE CTLR CAN USUALLY START, OR FORCE, TRACKING TO THE TARGET. BUT IN CERTAIN OBSERVED CASES, THE CTLR ALLEGES THAT THE DROPPED TAG IS NOT IN HIS 'CST' LIST AND CAN NOT BE MANUALLY STARTED. THE DATA TAG APPARENTLY HAS BEEN DROPPED FROM THE ENTIRE ARTS SYSTEM. THE CTLR ADVISED THAT HIS FAC HAS AN ASR-8 INSTALLED SYSTEM AND THAT THEIR AOS SUPPORT FAC IS SAN DIEGO, CA. RPTR STATES THAT THE FAC AOS SPECIALIST HAS ADVISED THAT THE ANOMALY HAS BEEN IDENTIFIED AS A 'DISASSOCIATE PROB MESSAGE CONTENT.' APPARENTLY THE FAC ARTS IIE SOFTWARE PARAMETERS ARE SUCH THAT WHEN TWO ARTS TAGS MERGE, AND IF THE SUM OF THEIR COMBINED ALTS EXCEED THE FAC FILTER LIMITS, THE COMPUTER DROPS ONE OR BOTH TAGS AS BEING OUT OF SYS PARAMETERS, AND THEREFORE TRACKING IS NOT REQUIRED. AOS HAS ADVISED THAT A FIX IS IN THE DEVELOPMENT IN WHICH FAC ALT FILTER LIMIT PARAMETERS WILL BE CHANGED FROM THE LOW: 1000 FT TO 100 FT, THE MAX ALT: FROM 45000 FT TO 99900 FT, AND THE RADAR RADIUS CHANGED FROM 55 NM TO 57 NM. SITE ADAPTATION IS EXPECTED WITHIN 30 DAYS.

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.