Narrative:

Contacted hef ATCT 10 NM northeast of hef, advised I was inbound for landing. Hef ATCT instructed me to enter left base, runway 16R, and to report 2 mi left base. About 3 NM from hef, I heard numerous aircraft in right traffic for runway 16R, so I tried to call and report 3 mi left base (in order to help remind ATCT I was there, even though they had requested 2 mi report). But my transmission was blocked by a call from inbound beechjet. After the beechjet repeated their call and hef ATCT responded to that aircraft, I called again and reported 2 mi left base. There was no response. It sounded like my transmission may have been blocked again, as another transmission was heard immediately after I let go of the push-to-talk switch. After hef ATCT finished talking to that aircraft, I called again and reported 1 mi left base. At this point I observed 2 aircraft -- 1 on right base to final and the other on right downwind, turning base. There was still no reply from hef ATCT. Because of the traffic on right base (and I was on 1 mi left base), I turned slightly right (away from the airport) to avoid a potentially hazardous situation. At this time hef ATCT called and asked if it was my aircraft on short left base. I replied in the affirmative, and said I had called 3 times but was possibly blocked. Hef ATCT instructed the other aircraft to go around, and cleared me to land runway 16R, which I proceeded to do without further incident. I had all other traffic in sight the entire time, so I don't think any midair collisions were imminent. But the situation still required the other aircraft to go around, and I believe ATC thought I had not made any position reports (when in fact I had made 3 but believe they were blocked by other xmissions). The primary problem in this situation was the extremely heavy radio traffic on the hef tower frequency. Even though I was careful to listen first, and make sure no other parties were talking before transmitting, it appears that 3 of my calls were blocked by other aircraft. A contributing factor was that I was unsure of the proper procedures to take in this situation. It was not exactly 'lost communication' since I could receive and transmit -- I just had the bad luck to have my xmissions stepped on multiple times. On the one hand, at the 2 mi left base position, I considered turning right and staying away from the airport until I could make a position report to the tower. On the other hand, I thought it would be better to continue making the left pattern, as that was the last instruction given by the tower. I did finally start to break off the pattern away from the airport when I thought it might present a hazardous situation, which is when ATCT called me and cleared me to land. In the future, I will attempt to make an earlier position report if the frequency is congested (ie, start trying to report 4-5 mi out). But on extremely busy days like today, my xmissions could still be blocked, given the high volume of traffic. Sits like these still might occur until the ATC system is moved to a data link format. Until then, hazardous sits are best avoided by keeping the eyes and ears peeled, in order to maintain separation.

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Original NASA ASRS Text

Title: CIRRUS SR20 PLT HAD REPEATED RADIO CALLS TO THE TWR BLOCKED AT HEF.

Narrative: CONTACTED HEF ATCT 10 NM NE OF HEF, ADVISED I WAS INBOUND FOR LNDG. HEF ATCT INSTRUCTED ME TO ENTER L BASE, RWY 16R, AND TO RPT 2 MI L BASE. ABOUT 3 NM FROM HEF, I HEARD NUMEROUS ACFT IN R TFC FOR RWY 16R, SO I TRIED TO CALL AND RPT 3 MI L BASE (IN ORDER TO HELP REMIND ATCT I WAS THERE, EVEN THOUGH THEY HAD REQUESTED 2 MI RPT). BUT MY XMISSION WAS BLOCKED BY A CALL FROM INBOUND BEECHJET. AFTER THE BEECHJET REPEATED THEIR CALL AND HEF ATCT RESPONDED TO THAT ACFT, I CALLED AGAIN AND RPTED 2 MI L BASE. THERE WAS NO RESPONSE. IT SOUNDED LIKE MY XMISSION MAY HAVE BEEN BLOCKED AGAIN, AS ANOTHER XMISSION WAS HEARD IMMEDIATELY AFTER I LET GO OF THE PUSH-TO-TALK SWITCH. AFTER HEF ATCT FINISHED TALKING TO THAT ACFT, I CALLED AGAIN AND RPTED 1 MI L BASE. AT THIS POINT I OBSERVED 2 ACFT -- 1 ON R BASE TO FINAL AND THE OTHER ON R DOWNWIND, TURNING BASE. THERE WAS STILL NO REPLY FROM HEF ATCT. BECAUSE OF THE TFC ON R BASE (AND I WAS ON 1 MI L BASE), I TURNED SLIGHTLY R (AWAY FROM THE ARPT) TO AVOID A POTENTIALLY HAZARDOUS SIT. AT THIS TIME HEF ATCT CALLED AND ASKED IF IT WAS MY ACFT ON SHORT L BASE. I REPLIED IN THE AFFIRMATIVE, AND SAID I HAD CALLED 3 TIMES BUT WAS POSSIBLY BLOCKED. HEF ATCT INSTRUCTED THE OTHER ACFT TO GO AROUND, AND CLRED ME TO LAND RWY 16R, WHICH I PROCEEDED TO DO WITHOUT FURTHER INCIDENT. I HAD ALL OTHER TFC IN SIGHT THE ENTIRE TIME, SO I DON'T THINK ANY MIDAIR COLLISIONS WERE IMMINENT. BUT THE SIT STILL REQUIRED THE OTHER ACFT TO GO AROUND, AND I BELIEVE ATC THOUGHT I HAD NOT MADE ANY POS RPTS (WHEN IN FACT I HAD MADE 3 BUT BELIEVE THEY WERE BLOCKED BY OTHER XMISSIONS). THE PRIMARY PROB IN THIS SIT WAS THE EXTREMELY HVY RADIO TFC ON THE HEF TWR FREQ. EVEN THOUGH I WAS CAREFUL TO LISTEN FIRST, AND MAKE SURE NO OTHER PARTIES WERE TALKING BEFORE XMITTING, IT APPEARS THAT 3 OF MY CALLS WERE BLOCKED BY OTHER ACFT. A CONTRIBUTING FACTOR WAS THAT I WAS UNSURE OF THE PROPER PROCS TO TAKE IN THIS SIT. IT WAS NOT EXACTLY 'LOST COM' SINCE I COULD RECEIVE AND XMIT -- I JUST HAD THE BAD LUCK TO HAVE MY XMISSIONS STEPPED ON MULTIPLE TIMES. ON THE ONE HAND, AT THE 2 MI L BASE POS, I CONSIDERED TURNING R AND STAYING AWAY FROM THE ARPT UNTIL I COULD MAKE A POS RPT TO THE TWR. ON THE OTHER HAND, I THOUGHT IT WOULD BE BETTER TO CONTINUE MAKING THE L PATTERN, AS THAT WAS THE LAST INSTRUCTION GIVEN BY THE TWR. I DID FINALLY START TO BREAK OFF THE PATTERN AWAY FROM THE ARPT WHEN I THOUGHT IT MIGHT PRESENT A HAZARDOUS SIT, WHICH IS WHEN ATCT CALLED ME AND CLRED ME TO LAND. IN THE FUTURE, I WILL ATTEMPT TO MAKE AN EARLIER POS RPT IF THE FREQ IS CONGESTED (IE, START TRYING TO RPT 4-5 MI OUT). BUT ON EXTREMELY BUSY DAYS LIKE TODAY, MY XMISSIONS COULD STILL BE BLOCKED, GIVEN THE HIGH VOLUME OF TFC. SITS LIKE THESE STILL MIGHT OCCUR UNTIL THE ATC SYS IS MOVED TO A DATA LINK FORMAT. UNTIL THEN, HAZARDOUS SITS ARE BEST AVOIDED BY KEEPING THE EYES AND EARS PEELED, IN ORDER TO MAINTAIN SEPARATION.

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.