Small aircraft on IFR flight plan temporarily lost communication due to using wrong switch.

Attributes
ACN	286949
Time
Date	199410
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : lit
State Reference	AR
Altitude	msl bound lower : 8000 msl bound upper : 8000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : mdt
Operator	general aviation : personal
Make Model Name	Super Skymaster
Operating Under FAR Part	Part 91
Flight Phase	cruise other
Route In Use	enroute airway : lit
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : atp
Experience	flight time last 90 days : 20 flight time total : 16000 flight time type : 700
ASRS Report	286949
Person 2
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Events
Anomaly	other anomaly other
Independent Detector	other flight crewa
Resolutory Action	flight crew : overcame equipment problem
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Approaching lit, monitoring approach controller frequency. Suddenly realized audio had ceased on both communication receivers. Checked frequencys, switched headset and tried right seat microphone/headset jacks to no avail. Southwest of lit, IMC condition existed at my altitude. Idented twice, 30 seconds apart on acquired ATC code, waited 15 seconds. Changed to transponder code 1200. Carefully checked visually for traffic and began descending left turn to maintain flight in VFR conditions. Remained above and outside of class 'C' airspace. Found all other avionic gear to be operating normally. Rechk of audio selector panel revealed that following tuning and identing lit runway 4 LOM on ADF. I had inadvertently deselected the 'automatic' function of the panel located next to ADF audio selector instead of ADF selector button. (Adjacent switches, same size and shape.) corrected switch position and re-established contact with lit approach control. Explained briefly, controller said no problem, I requested clearance over route filed, was cleared as filed at altitude requested (4000 ft MSL). On this audio panel, automatic switch matches receiver to selected transmitter (#1 or #2) with automatic off and no individual audio selection accomplished, no audio is received. If this switch were different size or shape, or a toggle type, I would aid identify. Callback conversation with reporter revealed the following information: reporter states that there is no easy fix without rewiring the audio unit. This is a standard radio audio selector panel and he believes the manufacturer has been made aware of the problem and will adapt for future units.

Original NASA ASRS Text

Title: SMA ON IFR FLT PLAN TEMPORARILY LOST COM DUE TO USING WRONG SWITCH.

Narrative: APCHING LIT, MONITORING APCH CTLR FREQ. SUDDENLY REALIZED AUDIO HAD CEASED ON BOTH COM RECEIVERS. CHKED FREQS, SWITCHED HEADSET AND TRIED R SEAT MIKE/HEADSET JACKS TO NO AVAIL. SW OF LIT, IMC CONDITION EXISTED AT MY ALT. IDENTED TWICE, 30 SECONDS APART ON ACQUIRED ATC CODE, WAITED 15 SECONDS. CHANGED TO XPONDER CODE 1200. CAREFULLY CHKED VISUALLY FOR TFC AND BEGAN DSNDING L TURN TO MAINTAIN FLT IN VFR CONDITIONS. REMAINED ABOVE AND OUTSIDE OF CLASS 'C' AIRSPACE. FOUND ALL OTHER AVIONIC GEAR TO BE OPERATING NORMALLY. RECHK OF AUDIO SELECTOR PANEL REVEALED THAT FOLLOWING TUNING AND IDENTING LIT RWY 4 LOM ON ADF. I HAD INADVERTENTLY DESELECTED THE 'AUTO' FUNCTION OF THE PANEL LOCATED NEXT TO ADF AUDIO SELECTOR INSTEAD OF ADF SELECTOR BUTTON. (ADJACENT SWITCHES, SAME SIZE AND SHAPE.) CORRECTED SWITCH POS AND RE-ESTABLISHED CONTACT WITH LIT APCH CTL. EXPLAINED BRIEFLY, CTLR SAID NO PROB, I REQUESTED CLRNC OVER RTE FILED, WAS CLRED AS FILED AT ALT REQUESTED (4000 FT MSL). ON THIS AUDIO PANEL, AUTO SWITCH MATCHES RECEIVER TO SELECTED XMITTER (#1 OR #2) WITH AUTO OFF AND NO INDIVIDUAL AUDIO SELECTION ACCOMPLISHED, NO AUDIO IS RECEIVED. IF THIS SWITCH WERE DIFFERENT SIZE OR SHAPE, OR A TOGGLE TYPE, I WOULD AID IDENT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATES THAT THERE IS NO EASY FIX WITHOUT REWIRING THE AUDIO UNIT. THIS IS A STANDARD RADIO AUDIO SELECTOR PANEL AND HE BELIEVES THE MANUFACTURER HAS BEEN MADE AWARE OF THE PROB AND WILL ADAPT FOR FUTURE UNITS.

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.