Narrative:

Dsr track ball enter key frequently interps a single push as 2 pushes. Aircraft #1's data block was overlapping aircraft #2's data block. Controller adjusted the data block offset via keyboard number keystroke between 1 and 9, followed by slewing the track ball to aircraft #1's position symbol and pushing track ball enter. The computer accepted the initial entry as intended, but then accepted the additional enter keystroke. Aircraft #1 was already handed off to the next sector, thus this additional keystroke caused the data block to drop off of the scope. The controller conducted his traffic search and saw that aircraft #2 had no traffic below him and cleared him lower. Aircraft #1's target displayed no mode C for 2 hits because the computer hadn't updated the scope. Only a slash and history was presented. This display was identical to aircraft below or above the sector altitude limits, but whose code was in the code list. So for 12 seconds, the controller would not recognize aircraft #1 as traffic for aircraft #2. Fortunately, the 2 aircraft flashed with each other when aircraft #2's temporary altitude was removed from the data block. Fortunately, aircraft #2 was at FL339 descending to FL310 and could be safely stopped again at FL330. At the very least, controllers should be made aware of this fault in the equipment to be overly sensitive to our inputs. Most controllers are not even aware that our dsr track balls are making random and sometimes dangerous entries. Ideally, the programming for the dsr would be reviewed to eliminate this double-click feature. Too many of my slant zeroes are dropping data blocks off of my scope prematurely and unintentionally. This does not always get noticed and would be easy to fix.

Google
 

Original NASA ASRS Text

Title: ZID CTLR EXPRESSED CONCERN REGARDING DSR TRACK BALL ANOMALY.

Narrative: DSR TRACK BALL ENTER KEY FREQUENTLY INTERPS A SINGLE PUSH AS 2 PUSHES. ACFT #1'S DATA BLOCK WAS OVERLAPPING ACFT #2'S DATA BLOCK. CTLR ADJUSTED THE DATA BLOCK OFFSET VIA KEYBOARD NUMBER KEYSTROKE BTWN 1 AND 9, FOLLOWED BY SLEWING THE TRACK BALL TO ACFT #1'S POS SYMBOL AND PUSHING TRACK BALL ENTER. THE COMPUTER ACCEPTED THE INITIAL ENTRY AS INTENDED, BUT THEN ACCEPTED THE ADDITIONAL ENTER KEYSTROKE. ACFT #1 WAS ALREADY HANDED OFF TO THE NEXT SECTOR, THUS THIS ADDITIONAL KEYSTROKE CAUSED THE DATA BLOCK TO DROP OFF OF THE SCOPE. THE CTLR CONDUCTED HIS TFC SEARCH AND SAW THAT ACFT #2 HAD NO TFC BELOW HIM AND CLRED HIM LOWER. ACFT #1'S TARGET DISPLAYED NO MODE C FOR 2 HITS BECAUSE THE COMPUTER HADN'T UPDATED THE SCOPE. ONLY A SLASH AND HISTORY WAS PRESENTED. THIS DISPLAY WAS IDENTICAL TO ACFT BELOW OR ABOVE THE SECTOR ALT LIMITS, BUT WHOSE CODE WAS IN THE CODE LIST. SO FOR 12 SECONDS, THE CTLR WOULD NOT RECOGNIZE ACFT #1 AS TFC FOR ACFT #2. FORTUNATELY, THE 2 ACFT FLASHED WITH EACH OTHER WHEN ACFT #2'S TEMPORARY ALT WAS REMOVED FROM THE DATA BLOCK. FORTUNATELY, ACFT #2 WAS AT FL339 DSNDING TO FL310 AND COULD BE SAFELY STOPPED AGAIN AT FL330. AT THE VERY LEAST, CTLRS SHOULD BE MADE AWARE OF THIS FAULT IN THE EQUIP TO BE OVERLY SENSITIVE TO OUR INPUTS. MOST CTLRS ARE NOT EVEN AWARE THAT OUR DSR TRACK BALLS ARE MAKING RANDOM AND SOMETIMES DANGEROUS ENTRIES. IDEALLY, THE PROGRAMMING FOR THE DSR WOULD BE REVIEWED TO ELIMINATE THIS DOUBLE-CLICK FEATURE. TOO MANY OF MY SLANT ZEROES ARE DROPPING DATA BLOCKS OFF OF MY SCOPE PREMATURELY AND UNINTENTIONALLY. THIS DOES NOT ALWAYS GET NOTICED AND WOULD BE EASY TO FIX.

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.