Narrative:

I was on the VOR runway 6 approach into cable airport (ccb). Upon termination of IFR I switched to the cable CTAF to make a 5 mi position report. I had the airport in sight and proceeded to descend to a traffic pattern altitude of 2300 ft MSL. When reaching 2 mi from the airport; I made a position report stating that I was setting up for a left downwind for runway 24. Another aircraft (C152) made his crosswind report and I quickly idented the traffic and turned left to allow the traffic to cross safely while telling him my intention of letting him go ahead of me in the traffic pattern on the radio. At this time I noticed another airplane (unidented low wing single engine) which took off shortly after the C152 that was making a climbing left turn right into my flight path. At this time; I pulled power and made an immediate descent to allow more room between myself and the unidented traffic. After the incident; I made another position report and heard no response from the target aircraft; which departed the pattern. The unidented aircraft must have missed my aircraft in his/her scan prior to turning; as I had made numerous position reports as a force of habit. I also certainly wasn't expecting another aircraft to take off so shortly after the C152. I am not aware of any evasive action taken by the unidented aircraft; since I heard no radio call. This issue may have been exacerbated by the fact that cable airport is located in a small hole on the edge of the ontario international airport (ont) class C airspace; which means that all departing VFR aircraft must turn left to use the traffic pattern for a north departure free of twred airspace after takeoff; as well as with the brackett airport (poc) class D airspace to the west.

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Original NASA ASRS Text

Title: C172 PLT ENTERING THE PATTERN AT CCB HAS AN NMAC WITH A DEPARTING LOW WING SEL NOT UTILIZING CTAF COM PROCEDURES.

Narrative: I WAS ON THE VOR RWY 6 APCH INTO CABLE ARPT (CCB). UPON TERMINATION OF IFR I SWITCHED TO THE CABLE CTAF TO MAKE A 5 MI POS RPT. I HAD THE ARPT IN SIGHT AND PROCEEDED TO DSND TO A TFC PATTERN ALT OF 2300 FT MSL. WHEN REACHING 2 MI FROM THE ARPT; I MADE A POS RPT STATING THAT I WAS SETTING UP FOR A L DOWNWIND FOR RWY 24. ANOTHER ACFT (C152) MADE HIS XWIND RPT AND I QUICKLY IDENTED THE TFC AND TURNED L TO ALLOW THE TFC TO CROSS SAFELY WHILE TELLING HIM MY INTENTION OF LETTING HIM GO AHEAD OF ME IN THE TFC PATTERN ON THE RADIO. AT THIS TIME I NOTICED ANOTHER AIRPLANE (UNIDENTED LOW WING SINGLE ENG) WHICH TOOK OFF SHORTLY AFTER THE C152 THAT WAS MAKING A CLBING L TURN RIGHT INTO MY FLT PATH. AT THIS TIME; I PULLED PWR AND MADE AN IMMEDIATE DSCNT TO ALLOW MORE ROOM BTWN MYSELF AND THE UNIDENTED TFC. AFTER THE INCIDENT; I MADE ANOTHER POS RPT AND HEARD NO RESPONSE FROM THE TARGET ACFT; WHICH DEPARTED THE PATTERN. THE UNIDENTED ACFT MUST HAVE MISSED MY ACFT IN HIS/HER SCAN PRIOR TO TURNING; AS I HAD MADE NUMEROUS POS RPTS AS A FORCE OF HABIT. I ALSO CERTAINLY WASN'T EXPECTING ANOTHER ACFT TO TAKE OFF SO SHORTLY AFTER THE C152. I AM NOT AWARE OF ANY EVASIVE ACTION TAKEN BY THE UNIDENTED ACFT; SINCE I HEARD NO RADIO CALL. THIS ISSUE MAY HAVE BEEN EXACERBATED BY THE FACT THAT CABLE ARPT IS LOCATED IN A SMALL HOLE ON THE EDGE OF THE ONTARIO INTL ARPT (ONT) CLASS C AIRSPACE; WHICH MEANS THAT ALL DEPARTING VFR ACFT MUST TURN L TO USE THE TFC PATTERN FOR A N DEP FREE OF TWRED AIRSPACE AFTER TKOF; AS WELL AS WITH THE BRACKETT ARPT (POC) CLASS D AIRSPACE TO THE W.

Data retrieved from NASA's ASRS site as of May 2009 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.