Controller claims that radios have many blind spots, making it difficult to hear all xmissions.

Attributes
ACN	234184
Time
Date	199302
Day	Thu
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : geg
State Reference	WA
Altitude	msl bound lower : 4000 msl bound upper : 4000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	tracon : geg tracon : suu
Operator	other
Make Model Name	Military Transport
Flight Phase	descent : approach
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Experience	controller military : 6 controller radar : 11
ASRS Report	234184
Person 2
Affiliation	government : military
Function	flight crew : captain oversight : pic
Qualification	pilot : military
Events
Anomaly	other anomaly other
Independent Detector	other controllera
Resolutory Action	none taken : unable
Consequence	Other
Supplementary
Primary Problem	Navigational Facility
Air Traffic Incident	other
Situations
Navigational Aid	Unspecified

Narrative:

The radios in the spokane area suffer from many blind spots. These occur at all altitudes and locations but are particularly bad at 2 locations, both being where you would need a readback of an ILS turn on. Many times, the pilot also misses the approach clearance, which can cause problems with separation. Callback conversation with reporter revealed the following: reporter states that this is an intermittent receiver problem that impacts certain UHF frequencys on approach control. The UHF antenna site was moved from the airport to 5 mi away on a hill recently, but the problem still exists. The aircraft involved are military trainers. It occurs on both the main and standby equipment. Frequencys impacted are 384.9 and 263.0. Reporter doesn't think a ucr has been filed. There have been no incidents because of this, however, many aircraft have gone through the final approach course. Reporter said that some days they have no problems while other days it might occur with every third or fourth aircraft.

Original NASA ASRS Text

Title: CTLR CLAIMS THAT RADIOS HAVE MANY BLIND SPOTS, MAKING IT DIFFICULT TO HEAR ALL XMISSIONS.

Narrative: THE RADIOS IN THE SPOKANE AREA SUFFER FROM MANY BLIND SPOTS. THESE OCCUR AT ALL ALTS AND LOCATIONS BUT ARE PARTICULARLY BAD AT 2 LOCATIONS, BOTH BEING WHERE YOU WOULD NEED A READBACK OF AN ILS TURN ON. MANY TIMES, THE PLT ALSO MISSES THE APCH CLRNC, WHICH CAN CAUSE PROBS WITH SEPARATION. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: RPTR STATES THAT THIS IS AN INTERMITTENT RECEIVER PROB THAT IMPACTS CERTAIN UHF FREQS ON APCH CTL. THE UHF ANTENNA SITE WAS MOVED FROM THE ARPT TO 5 MI AWAY ON A HILL RECENTLY, BUT THE PROB STILL EXISTS. THE ACFT INVOLVED ARE MIL TRAINERS. IT OCCURS ON BOTH THE MAIN AND STANDBY EQUIP. FREQS IMPACTED ARE 384.9 AND 263.0. RPTR DOESN'T THINK A UCR HAS BEEN FILED. THERE HAVE BEEN NO INCIDENTS BECAUSE OF THIS, HOWEVER, MANY ACFT HAVE GONE THROUGH THE FINAL APCH COURSE. RPTR SAID THAT SOME DAYS THEY HAVE NO PROBS WHILE OTHER DAYS IT MIGHT OCCUR WITH EVERY THIRD OR FOURTH ACFT.

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.