INTERMITTENT LOSS OF COM FREQ.

Narrative

MY SAFETY PLT AND I EXPERIENCED AN INTERMITTENT LOSS OF ATC RECEPTION WHILE PRACTICING NIGHT IFR APCHS IN A RADAR VECTORING ENVIRONMENT. THE FIRST INDICATION WAS THE SAFETY PLT'S COMPLETE LOSS OF XMIT AND RECEIVE CAPABILITY WITH ME VIA THE INTERCOM. ONCE HE GAVE UP TRYING TO RE- ESTABLISH SVC; THE SAFETY PLT DISCONNECTED HIS HEADSET; AND COINCIDENTALLY HE WARNED ME OF CONFLICTING TFC AND RECOMMENDED A CLB TO AVOID IT. WHILE DISTRACTED BY THE COM AND TFC PROBS WE WERE UNAWARE THAT ATC RECEPTION MUST HAVE BEEN AFFECTED TOO; BECAUSE WHEN CLR OF TFC; I TOLD ATC I'D HAD NO ADVISORY FROM THEM; AND THEY REPLIED THEY HAD BEEN TRYING TO REACH US FOR THE PAST 5 MI. THINKING THAT THE SAFETY PLT'S HEADSET HAD CAUSED THE RECEPTION LOSS AND BELIEVING THAT ITS DISCONNECTION HAD CLRED THE FAULT; WE INITIATED A PRACTICE APCH UNDER ATC DIRECTION. AS WE NEARED THE FINAL APCH COURSE I NOTED THAT WE HAD HEARD NO RECENT VOICE TFC ON FREQ SO I CALLED TO ASK IF THEY WERE STILL WITH US; AND THE CTLR REPLIED HE'D BEEN TRYING TO REACH US FOR 3 MI. I REALIZED THAT THE NATURE OF THE COM PROBS STILL ELUDED US; SO I CANCELED IFR AND SAID I'D GO HOME VFR. THE CTLR ASKED ME TO STAY WITH HIM AS HE WISHED TO STEER US OUT OF THE ATA; AND HE GAVE US A VECTOR OVER THE TOP OF THE LOC. SHORTLY; I REALIZED I'D LOST RECEPTION AGAIN. NO AMOUNT OF SWITCH FLIPPING; KNOB TWISTING OR CALLING ATC RESTORED THE LINK THIS TIME; SO I SQUAWKED 7600 AND PROCEEDED AS EARLIER DIRECTED. AS WE APCHED THE LOC THE SAFETY PLT AGAIN WARNED OF TFC; AND THIS TIME INITIATED A R 360 DEG TURN. UNSURE OF WHAT CONCERNED HIM I COMPLETED THE TURN AND ADVISED ATC OF WHAT WE WERE UP TO; STILL WITH NO RECEPTION FROM THEM. I CONTINUED TO SEEK AVIONICS SETTINGS THAT WOULD RESTORE COM; AND SUDDENLY WAS ABLE TO HEAR ATC OVER THE CABIN SPEAKER THOUGH STILL NOT THROUGH THE HEADSET (XMISSIONS WERE NEVER AFFECTED DURING THE WHOLE ORDEAL; THANKFULLY). I WAS GIVEN TRACON'S PHONE NUMBER AFTER LNDG; AND HAD A FRIENDLY CONVERSATION WITH THE SUPVR IN WHICH HE ASSURED ME HE WAS JUST CONCERNED THAT WE WERE 'ALL RIGHT' MENTALLY; NO DOUBT. WE HAVEN'T YET FATHOMED THE TECHNICAL PROB AFFLICTING THE AVIONICS; BUT THE ISSUE OF CONCERN TO THE ASRS; I THINK; IS THE COORD OF LIGHT PLANE DUAL PLT OP. LAST YR WHEN MY SAFETY PLT WAS PRACTICING APCHS AND I WAS RIDING SHOTGUN; I OBSERVED AN IMMINENT TFC CONFLICT; CALLED 'MY AIRPLANE' ON THE INTERCOM; AND TOOK THE NECESSARY EVASIVE ACTION. IN THE ABOVE INCIDENT; HOWEVER; THE SAFETY PLT MERELY ADVISED ME OF THE CONFLICT; FORCING ME TO COME OUT FROM UNDER THE HOOD; LOCATE THE TFC; PLAN AN EVASION; AND EXECUTE IT MYSELF. I TOLD THE SAFETY PLT THAT PROCESS WASTED PRECIOUS TIME AND I PREFERRED HIM TO TAKE COMMAND IN SUCH CRITICAL CASES. WHEN LATER WE WERE LEAVING THE ATA; SINCE HIS HEADSET WAS INOP HE WAS UNAWARE THAT I WAS UNDER ATC DIRECTION; AND PERHAPS NOT CONSCIOUS THAT OUR SIT HAD CHANGED TO VFR. SO HE ASSUMED CTL WHEN HE PERCEIVED AN APPARENT TFC CONFLICT; AS I'D ASKED HIM TO DO; EVEN THOUGH IT WAS INAPPROPRIATE IN OUR VFR ENVIRONMENT. NO DANGER TO ANY ACFT RESULTED FROM THIS INCIDENT; ATC WAS INFORMED OF OUR SIT AND INTENTIONS VIA OUR XMISSIONS; EVEN IF WE COULD HEAR THEM; AND THEY SEEMED SATISFIED THAT WE'D MADE THE BEST OF AN EVOLVING EQUIP PROB. BUT THE DIFFICULTY IS WORTH RECALLING BECAUSE OF THE EVIDENT BREAKDOWN OF COCKPIT COORD BTWN MY SAFETY PLT AND ME. THE FAA CONDUCTS VALUABLE PLT SEMINARS ON SUCH TOPICS AS WX AND USE OF THE ATC SYS (EG; OP RAINCHK) AND I WOULD RECOMMEND A NEW ONE ON LIGHT PLANE DUAL PLT COORD. IT WOULD BE OF GREAT VALUE TO US WHO DON'T NORMALLY OPERATE IN DUAL PLT SITS TO LEARN WHAT THE AIRLINES AND THEIR CTLRS HAVE TO TEACH US ABOUT BETTER COCKPIT COORD.