Narrative:

This flight was the initial test flight of an experimental aircraft with an experimental engine. The flight conditions specified by the FAA FSDO office were VFR operation, from and returning to camarillo (cma) airport. Actual conditions were about 11000 scattered to broken, visibility 30, wind calm. Prior to taxi the pilot informed the tower of the nature of the flight and his intentions (e.g. Climb to approximately 6000 ft MSL (5925 ft AGL) and remain about 3 mi north of cma for approximately 1 hour and return). Communications were good during taxi and takeoff clearance. The aircraft made a routine departure and as requested, called cma tower passing through 3000 ft. The tower acknowledged and authorized a frequency change. Soon afterward, the pilot was unable to contact his ground base although the ground base operators later told the pilot that they had received weak transmissions and had attempted to reply. The aircraft radio was new, from a major aircraft avionics manufacturer, and was installed by an aircraft avionics technician. At this writing, the avionics department is attempting to determine the case of this and subsequent problems. Throughout the flight the pilot was able to hear cma tower and cma ATIS clearly but never heard his ground base. As a result of this he believed that he had suffered a partial radio failure. This condition is being investigated. Approximately 45 mins into the flight, a beginning of engine roughness, coupled with a rise in cylinder head temperature caused the pilot to decide to land as soon as practical before the conditions reached emergency status. Descent toward the cma pattern was begun and repeated attempts were made to contact the cma tower with no response. Later discussion with the acftþs ground base personnel established that they had monitored at least some of these transmissions and had, in fact, called the cma tower on ground radio saying the aircraft seemed to be having radio problems and requesting light signals. No response to that request was received from cma tower. The aircraft entered the cma downwind pattern leg. Established appropriate spacing with the preceding aircraft and as the test aircraft was turning final the cma tower asked, þwhoþs the aircraft turning final?þ the pilot responded with the acftþs identify. Cma tower responded with the acftþs number and cleared the aircraft to land. The landing proceeded without incident. After landing, communications with ground control were intermittent and some of the taxi operation was accomplished through the use of visual signals. While the in-flight traffic pattern was not busy at the time, the local controller was being hvyily harassed by repeated calls from 1 or 2 aircraft awaiting departure. This and numerous examples of terrible radio procedure (i.e. People, including the tower, transmitting when others were talking on the frequency) provided a significant distraction to the local controller. It isnþt at all clear how many (if any) of the acftþs transmissions could have been heard by the local controller although at least some were heard by the acftþs ground base. The pilot believes that he acted in complete accordance with far paragraph 91.2 and further believes that any other alternative course of action would have resulted in increased risks to the lt, to the aircraft, and to persons on the ground. 2 possible actions to this sort of problem suggest themselves: 1)pilots in general need considerably improved training in correct radio procedures, including recognition of incipient controller workload saturation. 2) controllers should, as a matter of policy, acknowledge all calls from aircraft that might be in flight, even if this acknowledgement consists only of the acftþs identify and þstand byþ. Failure to do always leads the pilot to question whether his radio is operating properly and results in repeated calls, increased frequency congestion and ultimately in increased controller workload.

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Original NASA ASRS Text

Title: RADIO COM PROBLEM. LOSS OF RADIO CONTACT UNABLE TO ESTABLISH RADIO CONTACT.

Narrative: THIS FLT WAS THE INITIAL TEST FLT OF AN EXPERIMENTAL ACFT WITH AN EXPERIMENTAL ENG. THE FLT CONDITIONS SPECIFIED BY THE FAA FSDO OFFICE WERE VFR OP, FROM AND RETURNING TO CAMARILLO (CMA) ARPT. ACTUAL CONDITIONS WERE ABOUT 11000 SCATTERED TO BROKEN, VISIBILITY 30, WIND CALM. PRIOR TO TAXI THE PLT INFORMED THE TWR OF THE NATURE OF THE FLT AND HIS INTENTIONS (E.G. CLB TO APPROX 6000 FT MSL (5925 FT AGL) AND REMAIN ABOUT 3 MI N OF CMA FOR APPROX 1 HOUR AND RETURN). COMS WERE GOOD DURING TAXI AND TKOF CLRNC. THE ACFT MADE A ROUTINE DEP AND AS REQUESTED, CALLED CMA TWR PASSING THROUGH 3000 FT. THE TWR ACKNOWLEDGED AND AUTHORIZED A FREQ CHANGE. SOON AFTERWARD, THE PLT WAS UNABLE TO CONTACT HIS GND BASE ALTHOUGH THE GND BASE OPERATORS LATER TOLD THE PILOT THAT THEY HAD RECEIVED WEAK TRANSMISSIONS AND HAD ATTEMPTED TO REPLY. THE ACFT RADIO WAS NEW, FROM A MAJOR ACFT AVIONICS MANUFACTURER, AND WAS INSTALLED BY AN ACFT AVIONICS TECHNICIAN. AT THIS WRITING, THE AVIONICS DEPT IS ATTEMPTING TO DETERMINE THE CASE OF THIS AND SUBSEQUENT PROBLEMS. THROUGHOUT THE FLT THE PLT WAS ABLE TO HEAR CMA TWR AND CMA ATIS CLRLY BUT NEVER HEARD HIS GND BASE. AS A RESULT OF THIS HE BELIEVED THAT HE HAD SUFFERED A PARTIAL RADIO FAILURE. THIS CONDITION IS BEING INVESTIGATED. APPROX 45 MINS INTO THE FLT, A BEGINNING OF ENG ROUGHNESS, COUPLED WITH A RISE IN CYLINDER HEAD TEMP CAUSED THE PLT TO DECIDE TO LAND AS SOON AS PRACTICAL BEFORE THE CONDITIONS REACHED EMER STATUS. DSCNT TOWARD THE CMA PATTERN WAS BEGUN AND REPEATED ATTEMPTS WERE MADE TO CONTACT THE CMA TWR WITH NO RESPONSE. LATER DISCUSSION WITH THE ACFTþS GND BASE PERSONNEL ESTABLISHED THAT THEY HAD MONITORED AT LEAST SOME OF THESE TRANSMISSIONS AND HAD, IN FACT, CALLED THE CMA TWR ON GND RADIO SAYING THE ACFT SEEMED TO BE HAVING RADIO PROBLEMS AND REQUESTING LIGHT SIGNALS. NO RESPONSE TO THAT REQUEST WAS RECEIVED FROM CMA TWR. THE ACFT ENTERED THE CMA DOWNWIND PATTERN LEG. ESTABLISHED APPROPRIATE SPACING WITH THE PRECEDING ACFT AND AS THE TEST ACFT WAS TURNING FINAL THE CMA TWR ASKED, þWHOþS THE ACFT TURNING FINAL?þ THE PLT RESPONDED WITH THE ACFTþS IDENT. CMA TWR RESPONDED WITH THE ACFTþS NUMBER AND CLRED THE ACFT TO LAND. THE LNDG PROCEEDED WITHOUT INCIDENT. AFTER LNDG, COMS WITH GND CTL WERE INTERMITTENT AND SOME OF THE TAXI OP WAS ACCOMPLISHED THROUGH THE USE OF VISUAL SIGNALS. WHILE THE INFLT TFC PATTERN WAS NOT BUSY AT THE TIME, THE LCL CTLR WAS BEING HVYILY HARASSED BY REPEATED CALLS FROM 1 OR 2 ACFT AWAITING DEP. THIS AND NUMEROUS EXAMPLES OF TERRIBLE RADIO PROC (I.E. PEOPLE, INCLUDING THE TWR, XMITTING WHEN OTHERS WERE TALKING ON THE FREQ) PROVIDED A SIGNIFICANT DISTR TO THE LCL CTLR. IT ISNþT AT ALL CLR HOW MANY (IF ANY) OF THE ACFTþS TRANSMISSIONS COULD HAVE BEEN HEARD BY THE LCL CTLR ALTHOUGH AT LEAST SOME WERE HEARD BY THE ACFTþS GND BASE. THE PLT BELIEVES THAT HE ACTED IN COMPLETE ACCORDANCE WITH FAR PARAGRAPH 91.2 AND FURTHER BELIEVES THAT ANY OTHER ALTERNATIVE COURSE OF ACTION WOULD HAVE RESULTED IN INCREASED RISKS TO THE LT, TO THE ACFT, AND TO PERSONS ON THE GND. 2 POSSIBLE ACTIONS TO THIS SORT OF PROBLEM SUGGEST THEMSELVES: 1)PLTS IN GENERAL NEED CONSIDERABLY IMPROVED TRAINING IN CORRECT RADIO PROCS, INCLUDING RECOGNITION OF INCIPIENT CTLR WORKLOAD SATURATION. 2) CTLRS SHOULD, AS A MATTER OF POLICY, ACKNOWLEDGE ALL CALLS FROM ACFT THAT MIGHT BE IN FLT, EVEN IF THIS ACKNOWLEDGEMENT CONSISTS ONLY OF THE ACFTþS IDENT AND þSTAND BYþ. FAILURE TO DO ALWAYS LEADS THE PLT TO QUESTION WHETHER HIS RADIO IS OPERATING PROPERLY AND RESULTS IN REPEATED CALLS, INCREASED FREQ CONGESTION AND ULTIMATELY IN INCREASED CTLR WORKLOAD.

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.