Narrative:

Phx primary radar does not display a target unless associated with a beacon splat and full data block. Agreeing to a test, aircraft X departed on jun/sat/02 at XA38Z, off of runway 25R, with transponder off. 2 mi off departure end, no radar target, asked altitude -- 2800 ft climbing. Panel is set up correctly. Line of sight -- no factor. Filter limits -- correct. This occurs often. Size of aircraft is not a factor, as we have held helicopters, GA, and air carrier fit this problem. Possibly, this could be a software problem, or fine tuning is needed at the sight. You can't call traffic that you aren't displaying, and with a transponder turned off, that aircraft is in visible. Callback conversation with reporter revealed the following information: reporter advised that he has observed again this problem on his last work shift. The situation was addressed with the supervisor, who alerted maintenance. Later, maintenance advised the supervisor that it is a 'known problem' with 'no immediate solution available.'

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Original NASA ASRS Text

Title: P50 DEP CTLR IDENTS RADAR PROB. WHEN AN ACFT'S XPONDER IS OFF OR INOP, A PRIMARY RADAR RETURN IS NOT DISPLAYED.

Narrative: PHX PRIMARY RADAR DOES NOT DISPLAY A TARGET UNLESS ASSOCIATED WITH A BEACON SPLAT AND FULL DATA BLOCK. AGREEING TO A TEST, ACFT X DEPARTED ON JUN/SAT/02 AT XA38Z, OFF OF RWY 25R, WITH XPONDER OFF. 2 MI OFF DEP END, NO RADAR TARGET, ASKED ALT -- 2800 FT CLBING. PANEL IS SET UP CORRECTLY. LINE OF SIGHT -- NO FACTOR. FILTER LIMITS -- CORRECT. THIS OCCURS OFTEN. SIZE OF ACFT IS NOT A FACTOR, AS WE HAVE HELD HELIS, GA, AND ACR FIT THIS PROB. POSSIBLY, THIS COULD BE A SOFTWARE PROB, OR FINE TUNING IS NEEDED AT THE SIGHT. YOU CAN'T CALL TFC THAT YOU AREN'T DISPLAYING, AND WITH A XPONDER TURNED OFF, THAT ACFT IS IN VISIBLE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR ADVISED THAT HE HAS OBSERVED AGAIN THIS PROB ON HIS LAST WORK SHIFT. THE SIT WAS ADDRESSED WITH THE SUPVR, WHO ALERTED MAINT. LATER, MAINT ADVISED THE SUPVR THAT IT IS A 'KNOWN PROB' WITH 'NO IMMEDIATE SOLUTION AVAILABLE.'

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.