Narrative:

While holding at 10000 ft MSL at oab VOR, trying to establish communications with the field WX observer, the #2 navigation flag appeared and disappeared on the first officer's HSI. After receiving local WX we were cleared for the approach and switched to the unicom frequency. While descending in the holding pattern we broke out under the ceiling and saw the runway. During this descent the #2 navigation flag became more frequently intermittent and eventually became steadily in view. While circling the field in increasing rainfall, the #1 navigation flag began appearing intermittently to become steady by landing rollout. Prior to this series of events the #2 radio had a history of being intermittent for short periods of time (1 min or so). There was also a history of dual navigation failures while operating the aircraft in rain or sleet or other visible moisture. My concern with this situation is that we did not report our radio problems to ATC. The reason being was that the #2 navigation had just begun to be intermittent before we went to unicom. We also had a fairly high cockpit workload at the time. The regulation (91.187) states that a malfunction of navigational equipment occurring in-flight shall be reported 'as soon as practical.' in this situation it did not become practical until after landing and at this point it was no longer an issue. I believe that we had other priorities. After shutdown an appropriate entry was made in the aircraft logbook.

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Original NASA ASRS Text

Title: COMMUTER HAS VOR FLAGS APPEAR WHILE ON APCH, LEAVING HOLDING FOR CIRCLE TO LAND.

Narrative: WHILE HOLDING AT 10000 FT MSL AT OAB VOR, TRYING TO ESTABLISH COMS WITH THE FIELD WX OBSERVER, THE #2 NAV FLAG APPEARED AND DISAPPEARED ON THE FO'S HSI. AFTER RECEIVING LCL WX WE WERE CLRED FOR THE APCH AND SWITCHED TO THE UNICOM FREQ. WHILE DSNDING IN THE HOLDING PATTERN WE BROKE OUT UNDER THE CEILING AND SAW THE RWY. DURING THIS DSCNT THE #2 NAV FLAG BECAME MORE FREQUENTLY INTERMITTENT AND EVENTUALLY BECAME STEADILY IN VIEW. WHILE CIRCLING THE FIELD IN INCREASING RAINFALL, THE #1 NAV FLAG BEGAN APPEARING INTERMITTENTLY TO BECOME STEADY BY LNDG ROLLOUT. PRIOR TO THIS SERIES OF EVENTS THE #2 RADIO HAD A HISTORY OF BEING INTERMITTENT FOR SHORT PERIODS OF TIME (1 MIN OR SO). THERE WAS ALSO A HISTORY OF DUAL NAV FAILURES WHILE OPERATING THE ACFT IN RAIN OR SLEET OR OTHER VISIBLE MOISTURE. MY CONCERN WITH THIS SIT IS THAT WE DID NOT RPT OUR RADIO PROBS TO ATC. THE REASON BEING WAS THAT THE #2 NAV HAD JUST BEGUN TO BE INTERMITTENT BEFORE WE WENT TO UNICOM. WE ALSO HAD A FAIRLY HIGH COCKPIT WORKLOAD AT THE TIME. THE REG (91.187) STATES THAT A MALFUNCTION OF NAVIGATIONAL EQUIP OCCURRING INFLT SHALL BE RPTED 'AS SOON AS PRACTICAL.' IN THIS SIT IT DID NOT BECOME PRACTICAL UNTIL AFTER LNDG AND AT THIS POINT IT WAS NO LONGER AN ISSUE. I BELIEVE THAT WE HAD OTHER PRIORITIES. AFTER SHUTDOWN AN APPROPRIATE ENTRY WAS MADE IN THE ACFT LOGBOOK.

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.