Narrative:

I was the PF on a flight to vny from smo with another instructor from my flight school. We were going to vny to pick up another aircraft that had been left at vny the previous night. The other instructor was essentially acting as PNF -- working the radios. Due to WX conditions, we filed IFR (tower en route) to vny. On our climb out of smo, we started experiencing radio breakup (had to have ATC repeat several communications). This sort of broken communication continued after our leveloff and we heard ATC instruct us to join the lax 316 degree radial to silex (as per our clearance). After a couple mins, we copied an instruction to fly a heading as a vector to the ILS runway 16R approach at vny. That was the last transmission we were able to receive clearly. We continued on this heading and at our assigned altitude (5000 ft) encountered VMC. Due to the continuing problems with the communication radios, we attempted receiving vny ATIS and talking to socal approach on a handheld radio. This did not result in any improvement. Through the aircraft radios, we received very broken pieces of instruction from socal approach -- including an announcement about a possible stuck microphone on the frequency (120.4). We unplugged the aircraft's hand microphone to eliminate this as a potential source of the communication troubles, but did not notice much improvement. We continued in VMC on our assigned heading and altitude until we caught part of a transmission from socal instructing us to join the fim 053 degree radial to umber intersection. We did this, and believing the radios still suspect, squawked 7600, proceeded to umber. As we joined the final approach course at vny, we were again able to get enough of socal approach's instructions to understand that they (socal) wanted us on the ILS at vny. We shot the approach, reporting our progress, and were able to acknowledge a clearance to land from vny tower. We then landed without incident and spoke to the supervisor at socal to let him know we had landed safely and to discuss the lost communications. We suspect the problem was a short in one of the push-to-talk switches which 'drowned out' everything. (This agrees with socal's announcement about a stuck microphone.) it also explains why we did not get any improvement in communicating with socal on the handheld radio. It also agrees with socal's ability to 'hear parts of our conversation,' as they told us after the flight.

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Original NASA ASRS Text

Title: PLT OF A PA28 HAS STUCK MIKE SOON AFTER IFR DEP CAUSING BREAK IN NORMAL COMS WITH ATC. PARTIAL COMS WERE RE-ESTABLISHED WITH ATC AND A NORMAL ILS APCH WAS MADE IN VFR CONDITIONS.

Narrative: I WAS THE PF ON A FLT TO VNY FROM SMO WITH ANOTHER INSTRUCTOR FROM MY FLT SCHOOL. WE WERE GOING TO VNY TO PICK UP ANOTHER ACFT THAT HAD BEEN LEFT AT VNY THE PREVIOUS NIGHT. THE OTHER INSTRUCTOR WAS ESSENTIALLY ACTING AS PNF -- WORKING THE RADIOS. DUE TO WX CONDITIONS, WE FILED IFR (TWR ENRTE) TO VNY. ON OUR CLB OUT OF SMO, WE STARTED EXPERIENCING RADIO BREAKUP (HAD TO HAVE ATC REPEAT SEVERAL COMS). THIS SORT OF BROKEN COM CONTINUED AFTER OUR LEVELOFF AND WE HEARD ATC INSTRUCT US TO JOIN THE LAX 316 DEG RADIAL TO SILEX (AS PER OUR CLRNC). AFTER A COUPLE MINS, WE COPIED AN INSTRUCTION TO FLY A HDG AS A VECTOR TO THE ILS RWY 16R APCH AT VNY. THAT WAS THE LAST XMISSION WE WERE ABLE TO RECEIVE CLRLY. WE CONTINUED ON THIS HDG AND AT OUR ASSIGNED ALT (5000 FT) ENCOUNTERED VMC. DUE TO THE CONTINUING PROBS WITH THE COM RADIOS, WE ATTEMPTED RECEIVING VNY ATIS AND TALKING TO SOCAL APCH ON A HANDHELD RADIO. THIS DID NOT RESULT IN ANY IMPROVEMENT. THROUGH THE ACFT RADIOS, WE RECEIVED VERY BROKEN PIECES OF INSTRUCTION FROM SOCAL APCH -- INCLUDING AN ANNOUNCEMENT ABOUT A POSSIBLE STUCK MIKE ON THE FREQ (120.4). WE UNPLUGGED THE ACFT'S HAND MIKE TO ELIMINATE THIS AS A POTENTIAL SOURCE OF THE COM TROUBLES, BUT DID NOT NOTICE MUCH IMPROVEMENT. WE CONTINUED IN VMC ON OUR ASSIGNED HDG AND ALT UNTIL WE CAUGHT PART OF A XMISSION FROM SOCAL INSTRUCTING US TO JOIN THE FIM 053 DEG RADIAL TO UMBER INTXN. WE DID THIS, AND BELIEVING THE RADIOS STILL SUSPECT, SQUAWKED 7600, PROCEEDED TO UMBER. AS WE JOINED THE FINAL APCH COURSE AT VNY, WE WERE AGAIN ABLE TO GET ENOUGH OF SOCAL APCH'S INSTRUCTIONS TO UNDERSTAND THAT THEY (SOCAL) WANTED US ON THE ILS AT VNY. WE SHOT THE APCH, RPTING OUR PROGRESS, AND WERE ABLE TO ACKNOWLEDGE A CLRNC TO LAND FROM VNY TWR. WE THEN LANDED WITHOUT INCIDENT AND SPOKE TO THE SUPVR AT SOCAL TO LET HIM KNOW WE HAD LANDED SAFELY AND TO DISCUSS THE LOST COMS. WE SUSPECT THE PROB WAS A SHORT IN ONE OF THE PUSH-TO-TALK SWITCHES WHICH 'DROWNED OUT' EVERYTHING. (THIS AGREES WITH SOCAL'S ANNOUNCEMENT ABOUT A STUCK MIKE.) IT ALSO EXPLAINS WHY WE DID NOT GET ANY IMPROVEMENT IN COMMUNICATING WITH SOCAL ON THE HANDHELD RADIO. IT ALSO AGREES WITH SOCAL'S ABILITY TO 'HEAR PARTS OF OUR CONVERSATION,' AS THEY TOLD US AFTER THE FLT.

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.