Private pilot experiences a loss of communication frequency in a C172 in the traffic pattern at smf,...

Attributes
ACN	539391
Time
Date	200202
Day	Wed
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : smf.airport
State Reference	CA
Altitude	agl single value : 1000
Environment
Light	Night
Aircraft 1
Controlling Facilities	tracon : mcc.tracon tower : smf.tower
Operator	general aviation : personal
Make Model Name	Skyhawk 172/Cutlass 172
Operating Under FAR Part	Part 91
Flight Phase	descent : approach
Route In Use	approach : traffic pattern
Flight Plan	None
Person 1
Affiliation	other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : private
Experience	flight time total : 316 flight time type : 316
ASRS Report	539391
Person 2
Affiliation	government : faa
Function	controller : local
Events
Anomaly	aircraft equipment problem : critical non adherence : clearance other anomaly other other spatial deviation
Independent Detector	other controllera other flight crewa
Resolutory Action	controller : issued new clearance flight crew : executed missed approach other
Consequence	other
Supplementary
Problem Areas	Airspace Structure Flight Crew Human Performance Aircraft
Primary Problem	Aircraft

Narrative:

Was practicing takeoff's and lndgs at twred field, at night, at smf. Smf tower had me turn out, around, then cleared for landing runway 16L. There was some static noise now on communication radio. Broken transmission from tower came through, saying my transponder was now non interrogating. I continued on downwind, then base turn to final. (During this time, there may have been more xmissions I did no hear). Turning on final, there was more broken xmissions and I could not clearly hear myself transmitting back. Broke off approach, went east at 1000 ft, heard tower then say 'C172, if you can hear this transmission, leave class C to the east.' which, is what I was doing. At this time, became clear that communication had suddenly failed. I left smf C airspace, pwred all items down. We were experiencing a charging system problem, with continuous discharge on ammeter. Turned back on #1 communication and could get 2-WAY communication with sac approach. Turned on #2 communication, too much drain, no communication at all. Left #1 communication on for hasty retreat to sutter county airport. In future, will fly with battery-pwred transceiver and GPS. I'm suspicious that, in the few mins that this occurred, we may not have heard some other xmissions to me, from smf tower. They couldn't hear mine.

Original NASA ASRS Text

Title: PVT PLT EXPERIENCES A LOSS OF COM FREQ IN A C172 IN THE TFC PATTERN AT SMF, CA.

Narrative: WAS PRACTICING TKOF'S AND LNDGS AT TWRED FIELD, AT NIGHT, AT SMF. SMF TWR HAD ME TURN OUT, AROUND, THEN CLRED FOR LNDG RWY 16L. THERE WAS SOME STATIC NOISE NOW ON COM RADIO. BROKEN XMISSION FROM TWR CAME THROUGH, SAYING MY XPONDER WAS NOW NON INTERROGATING. I CONTINUED ON DOWNWIND, THEN BASE TURN TO FINAL. (DURING THIS TIME, THERE MAY HAVE BEEN MORE XMISSIONS I DID NO HEAR). TURNING ON FINAL, THERE WAS MORE BROKEN XMISSIONS AND I COULD NOT CLRLY HEAR MYSELF XMITTING BACK. BROKE OFF APCH, WENT E AT 1000 FT, HEARD TWR THEN SAY 'C172, IF YOU CAN HEAR THIS XMISSION, LEAVE CLASS C TO THE E.' WHICH, IS WHAT I WAS DOING. AT THIS TIME, BECAME CLR THAT COM HAD SUDDENLY FAILED. I LEFT SMF C AIRSPACE, PWRED ALL ITEMS DOWN. WE WERE EXPERIENCING A CHARGING SYS PROB, WITH CONTINUOUS DISCHARGE ON AMMETER. TURNED BACK ON #1 COM AND COULD GET 2-WAY COM WITH SAC APCH. TURNED ON #2 COM, TOO MUCH DRAIN, NO COM AT ALL. LEFT #1 COM ON FOR HASTY RETREAT TO SUTTER COUNTY ARPT. IN FUTURE, WILL FLY WITH BATTERY-PWRED TRANSCEIVER AND GPS. I'M SUSPICIOUS THAT, IN THE FEW MINS THAT THIS OCCURRED, WE MAY NOT HAVE HEARD SOME OTHER XMISSIONS TO ME, FROM SMF TWR. THEY COULDN'T HEAR MINE.

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.

Private pilot experiences a loss of communication frequency in a C172 in the traffic pattern at smf, ca.