Narrative:

Tower just opened. I was working tower, local control. I cleared small aircraft X for takeoff. I previously cleared small aircraft Y to land runway 7R. I looked at runway 7R and observed an small aircraft clearing the active. I took this to be the small aircraft Y I cleared to land. It was not. Another small aircraft Z, which did not have transponder set to 7600, landed without communicating. This caused small aircraft Y to go around. Small aircraft Y came in close proximity to small aircraft X. The failure of small aircraft Z pilot to communicate to ATC or advise intentions on CTAF along with his failure to have his transponder on and on 7600 caused an unsafe condition. The pilot also failed to follow lost communication procedures.

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Original NASA ASRS Text

Title: SMA X UNAUTHORIZED LNDG CAUSED SMA Y TO GAR AND COME IN CLOSE PROX OF ACFT TO SMA X. PLTDEV. SEE AND AVOID CONCEPT.

Narrative: TWR JUST OPENED. I WAS WORKING TWR, LCL CTL. I CLRED SMA X FOR TKOF. I PREVIOUSLY CLRED SMA Y TO LAND RWY 7R. I LOOKED AT RWY 7R AND OBSERVED AN SMA CLRING THE ACTIVE. I TOOK THIS TO BE THE SMA Y I CLRED TO LAND. IT WAS NOT. ANOTHER SMA Z, WHICH DID NOT HAVE TRANSPONDER SET TO 7600, LANDED WITHOUT COMMUNICATING. THIS CAUSED SMA Y TO GAR. SMA Y CAME IN CLOSE PROX TO SMA X. THE FAILURE OF SMA Z PLT TO COMMUNICATE TO ATC OR ADVISE INTENTIONS ON CTAF ALONG WITH HIS FAILURE TO HAVE HIS TRANSPONDER ON AND ON 7600 CAUSED AN UNSAFE CONDITION. THE PLT ALSO FAILED TO FOLLOW LOST COM PROCS.

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.