Narrative:

We were inbound VFR to sql and reported to the sql tower 2 mi southeast stanford university at 2500 ft MSL. This is approximately 8 mi southeast of sql. Sql tower replied 'radar contact overhead slac (stanford linear accelerator center)' which at that point was about 3 mi away. That seemed close enough to me, so I replied, 'roger.' shortly thereafter, tower asked if I was 'identing 1200.' since I was flying VFR and squawking 1200, I replied 'affirmative.' shortly after that, the tower asked me to confirm I was over slac. At this point I figured something was up and said, 'negative' and repeated I was southeast of stanford. Tower then gave me a 12 O'clock, 1/2 mi, same altitude TA, and we crossed right behind a cessna bound for pao. Standard procedure for pao is to report over slac and identify. Pao is approximately 5 mi east of slac. I was cutting directly across this path. I should have reported 'negative identify' when asked. It did not occur to me that the tower was trying to distinguish me from another target. I should have queried the tower when they gave an incorrect position on initial radar contact. Towers in close proximity might consider assigning different transponder codes to inbound VFR traffic, eg, 1201 for pao and 1202 for sql.

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Original NASA ASRS Text

Title: C172 PLT GAVE POS RPT TO TWR INBOUND FOR LNDG, TWR IDENTED A RADAR TARGET AND QUERIED RPTR IF IT WAS HIM TO WHICH HE AFFIRMED. ACTUALLY IT WAS ANOTHER ACFT GOING TO A NEIGHBORING ARPT AND TWR AGAIN QUESTIONED RPTR WHO THEN REALIZED THE TARGET WAS A DIFFERENT ACFT AS TWR GAVE RPTR TFC ALERT ON THAT TFC.

Narrative: WE WERE INBOUND VFR TO SQL AND RPTED TO THE SQL TWR 2 MI SE STANFORD UNIVERSITY AT 2500 FT MSL. THIS IS APPROX 8 MI SE OF SQL. SQL TWR REPLIED 'RADAR CONTACT OVERHEAD SLAC (STANFORD LINEAR ACCELERATOR CTR)' WHICH AT THAT POINT WAS ABOUT 3 MI AWAY. THAT SEEMED CLOSE ENOUGH TO ME, SO I REPLIED, 'ROGER.' SHORTLY THEREAFTER, TWR ASKED IF I WAS 'IDENTING 1200.' SINCE I WAS FLYING VFR AND SQUAWKING 1200, I REPLIED 'AFFIRMATIVE.' SHORTLY AFTER THAT, THE TWR ASKED ME TO CONFIRM I WAS OVER SLAC. AT THIS POINT I FIGURED SOMETHING WAS UP AND SAID, 'NEGATIVE' AND REPEATED I WAS SE OF STANFORD. TWR THEN GAVE ME A 12 O'CLOCK, 1/2 MI, SAME ALT TA, AND WE CROSSED RIGHT BEHIND A CESSNA BOUND FOR PAO. STANDARD PROC FOR PAO IS TO RPT OVER SLAC AND IDENT. PAO IS APPROX 5 MI E OF SLAC. I WAS CUTTING DIRECTLY ACROSS THIS PATH. I SHOULD HAVE RPTED 'NEGATIVE IDENT' WHEN ASKED. IT DID NOT OCCUR TO ME THAT THE TWR WAS TRYING TO DISTINGUISH ME FROM ANOTHER TARGET. I SHOULD HAVE QUERIED THE TWR WHEN THEY GAVE AN INCORRECT POS ON INITIAL RADAR CONTACT. TWRS IN CLOSE PROX MIGHT CONSIDER ASSIGNING DIFFERENT XPONDER CODES TO INBOUND VFR TFC, EG, 1201 FOR PAO AND 1202 FOR SQL.

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.