Narrative:

What happened today is a superb example of confusion and misunderstanding during radio communication. The first factor contributing was unusual bay departure frequency assignments for my training flight (I am a cfii) from sjc to mer. The second contributing factor was that the runway in use was runway 11 (it is usually 29) at sjc. The third contributing factor was that 3 cessna's on the same bay frequency had similar sounding call signs (xya, xyb, and xyz (my aircraft)). The ATC controller on 121.3 had quite a time trying to get the correct airplane to respond, assuming he was talking to the airplane he thought he was talking to. The 3 airplanes (including my student) had a difficult time understanding which calls were for them and, more importantly, which calls were not for them. This letter is written not as a complaint, but as an example of the very good advice in aim to listen carefully and speak clearly. The way that my aircraft got mixed up in this appears to have been a result of an ATC mix-up whose source I cannot determine. The direct route from sjc to atwater is magnetic course 075 degrees. We (my student and I) expected our departure control frequency to be 121.3. But when we called sjc clearance delivery for our clearance 'VFR atwater,' the controller assigned 120.1. We asked for confirmation (actually, my student wrongly read back 121.3). The controller repeated 120.1. When cleared for takeoff we asked for and got a departure left turn (from runway 11) to heading 060 degrees. Then the tower controller told us 'aircraft xyz contact bay departure, 121.3,' and we complied. When we tried to check in on 121.3, the controller did not acknowledge our call, but was already talking to aircraft xyz among others. Then, shortly after we checked in, cessna aircraft xyb checked in, and he was a student pilot, solo. So imagine the poor controller. He's got: aircraft xya -- who is trying to get through sjc class C to pao. Aircraft xyb -- a student pilot pop-up just leaving sjc going toward the north. Aircraft xyz -- my flight with a student pilot who is just learning to talk on the radio and, he was not expecting us, but we thought he was expecting us. No violations occurred and everybody got where they were going ok, but you can see the potential for danger. Again, a great lesson in the importance of listening carefully first! I still don't know, and can't figure out why, the frequency assignment mix-up for my flight, but at least it gave me a great real world example to teach my student and object lesson.

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Original NASA ASRS Text

Title: C172 INSTRUCTOR, WITH STUDENT, BECAME INVOLVED WITH DEP CLRNC CONFUSION DUE TO 3 ACFT WITH SIMILAR SOUNDING CALL SIGNS.

Narrative: WHAT HAPPENED TODAY IS A SUPERB EXAMPLE OF CONFUSION AND MISUNDERSTANDING DURING RADIO COM. THE FIRST FACTOR CONTRIBUTING WAS UNUSUAL BAY DEP FREQ ASSIGNMENTS FOR MY TRAINING FLT (I AM A CFII) FROM SJC TO MER. THE SECOND CONTRIBUTING FACTOR WAS THAT THE RWY IN USE WAS RWY 11 (IT IS USUALLY 29) AT SJC. THE THIRD CONTRIBUTING FACTOR WAS THAT 3 CESSNA'S ON THE SAME BAY FREQ HAD SIMILAR SOUNDING CALL SIGNS (XYA, XYB, AND XYZ (MY ACFT)). THE ATC CTLR ON 121.3 HAD QUITE A TIME TRYING TO GET THE CORRECT AIRPLANE TO RESPOND, ASSUMING HE WAS TALKING TO THE AIRPLANE HE THOUGHT HE WAS TALKING TO. THE 3 AIRPLANES (INCLUDING MY STUDENT) HAD A DIFFICULT TIME UNDERSTANDING WHICH CALLS WERE FOR THEM AND, MORE IMPORTANTLY, WHICH CALLS WERE NOT FOR THEM. THIS LETTER IS WRITTEN NOT AS A COMPLAINT, BUT AS AN EXAMPLE OF THE VERY GOOD ADVICE IN AIM TO LISTEN CAREFULLY AND SPEAK CLRLY. THE WAY THAT MY ACFT GOT MIXED UP IN THIS APPEARS TO HAVE BEEN A RESULT OF AN ATC MIX-UP WHOSE SOURCE I CANNOT DETERMINE. THE DIRECT RTE FROM SJC TO ATWATER IS MAGNETIC COURSE 075 DEGS. WE (MY STUDENT AND I) EXPECTED OUR DEP CTL FREQ TO BE 121.3. BUT WHEN WE CALLED SJC CLRNC DELIVERY FOR OUR CLRNC 'VFR ATWATER,' THE CTLR ASSIGNED 120.1. WE ASKED FOR CONFIRMATION (ACTUALLY, MY STUDENT WRONGLY READ BACK 121.3). THE CTLR REPEATED 120.1. WHEN CLRED FOR TKOF WE ASKED FOR AND GOT A DEP L TURN (FROM RWY 11) TO HDG 060 DEGS. THEN THE TWR CTLR TOLD US 'ACFT XYZ CONTACT BAY DEP, 121.3,' AND WE COMPLIED. WHEN WE TRIED TO CHK IN ON 121.3, THE CTLR DID NOT ACKNOWLEDGE OUR CALL, BUT WAS ALREADY TALKING TO ACFT XYZ AMONG OTHERS. THEN, SHORTLY AFTER WE CHKED IN, CESSNA ACFT XYB CHKED IN, AND HE WAS A STUDENT PLT, SOLO. SO IMAGINE THE POOR CTLR. HE'S GOT: ACFT XYA -- WHO IS TRYING TO GET THROUGH SJC CLASS C TO PAO. ACFT XYB -- A STUDENT PLT POP-UP JUST LEAVING SJC GOING TOWARD THE N. ACFT XYZ -- MY FLT WITH A STUDENT PLT WHO IS JUST LEARNING TO TALK ON THE RADIO AND, HE WAS NOT EXPECTING US, BUT WE THOUGHT HE WAS EXPECTING US. NO VIOLATIONS OCCURRED AND EVERYBODY GOT WHERE THEY WERE GOING OK, BUT YOU CAN SEE THE POTENTIAL FOR DANGER. AGAIN, A GREAT LESSON IN THE IMPORTANCE OF LISTENING CAREFULLY FIRST! I STILL DON'T KNOW, AND CAN'T FIGURE OUT WHY, THE FREQ ASSIGNMENT MIX-UP FOR MY FLT, BUT AT LEAST IT GAVE ME A GREAT REAL WORLD EXAMPLE TO TEACH MY STUDENT AND OBJECT LESSON.

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.