PA28 pilot landing dsm is able to hear dsm approach control on radio, but is unable to transmit.

Attributes
ACN	592566
Time
Date	200309
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : dsm.airport
State Reference	IA
Altitude	msl bound lower : 957 msl bound upper : 2500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : dsm.tracon tower : dsm.tower
Operator	general aviation : personal
Make Model Name	PA-28 Cherokee/Archer II/Dakota/Pillan/Warrior
Operating Under FAR Part	Part 91
Flight Phase	descent : approach landing : roll
Flight Plan	None
Person 1
Affiliation	other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : private
Experience	flight time last 90 days : 93 flight time total : 599 flight time type : 50
ASRS Report	592566
Person 2
Affiliation	government : faa
Function	controller : approach
Events
Anomaly	aircraft equipment problem : less severe other anomaly other
Independent Detector	other controllera other controllerb other flight crewa
Resolutory Action	controller : provided flight assist controller : issued new clearance
Supplementary
Problem Areas	Aircraft
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

I was approaching the class C controled airspace of dsm, ia. I had got the WX and then called the approach to request permission to land at dsm. At this time I was still outside of the airspace and trying to establish 2-WAY radio communication. The reply I received was that the ATC controller could hear my microphone being keyed, but could not hear my voice. I repeated my call and he again replied no voice. ATC then asked for the airplane calling approach to squawk a unique frequency and to identify. I complied with the instruction. ATC then advised me that radar contact was made and that I should fly in for runway 13. Further commands were then given by ATC each time asking for confirmation by pressing identify. I made straight-in and landed on runway 13 and was then guided directly to the radio shop. A minor short circuit was discovered and repaired and I then departed for dsm class C airspace. I had heard traffic on the way down to dsm, so I realize that this is a busy airport and hope to not have a recurrence of this problem.

Original NASA ASRS Text

Title: PA28 PLT LNDG DSM IS ABLE TO HEAR DSM APCH CTL ON RADIO, BUT IS UNABLE TO XMIT.

Narrative: I WAS APCHING THE CLASS C CTLED AIRSPACE OF DSM, IA. I HAD GOT THE WX AND THEN CALLED THE APCH TO REQUEST PERMISSION TO LAND AT DSM. AT THIS TIME I WAS STILL OUTSIDE OF THE AIRSPACE AND TRYING TO ESTABLISH 2-WAY RADIO COM. THE REPLY I RECEIVED WAS THAT THE ATC CTLR COULD HEAR MY MIKE BEING KEYED, BUT COULD NOT HEAR MY VOICE. I REPEATED MY CALL AND HE AGAIN REPLIED NO VOICE. ATC THEN ASKED FOR THE AIRPLANE CALLING APCH TO SQUAWK A UNIQUE FREQ AND TO IDENT. I COMPLIED WITH THE INSTRUCTION. ATC THEN ADVISED ME THAT RADAR CONTACT WAS MADE AND THAT I SHOULD FLY IN FOR RWY 13. FURTHER COMMANDS WERE THEN GIVEN BY ATC EACH TIME ASKING FOR CONFIRMATION BY PRESSING IDENT. I MADE STRAIGHT-IN AND LANDED ON RWY 13 AND WAS THEN GUIDED DIRECTLY TO THE RADIO SHOP. A MINOR SHORT CIRCUIT WAS DISCOVERED AND REPAIRED AND I THEN DEPARTED FOR DSM CLASS C AIRSPACE. I HAD HEARD TFC ON THE WAY DOWN TO DSM, SO I REALIZE THAT THIS IS A BUSY ARPT AND HOPE TO NOT HAVE A RECURRENCE OF THIS PROB.

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.