Corp aircraft has radio channel problems on ILS approach.

Attributes
ACN	189707
Time
Date	199109
Day	Tue
Place
Locale Reference	airport : sfo
State Reference	CA
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : oak
Operator	general aviation : corporate
Make Model Name	Light Transport
Flight Phase	descent : approach
Flight Plan	VFR
Person 1
Affiliation	Other
Function	observation : observer
Qualification	pilot : atp
Experience	flight time last 90 days : 50 flight time total : 4500 flight time type : 2000
ASRS Report	189707
Person 2
Affiliation	Other
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	other flight crewa
Resolutory Action	none taken : detected after the fact
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

On approach to runway 28L at san francisco international airport our navigation receivers (2) were tuned to the localizer frequency of 109.55. The aircraft had off flags on both the localizer and GS, although it was receiving an identify. The approach was completed in visual conditions. Upon investigation we found that although we had 40 channel control heads installed in our aircraft we only had 20 channel navigation receivers. We have been told that other operators have experienced the same problem.

Original NASA ASRS Text

Title: CORP ACFT HAS RADIO CHANNEL PROBLEMS ON ILS APCH.

Narrative: ON APCH TO RWY 28L AT SAN FRANCISCO INTL ARPT OUR NAV RECEIVERS (2) WERE TUNED TO THE LOC FREQ OF 109.55. THE ACFT HAD OFF FLAGS ON BOTH THE LOC AND GS, ALTHOUGH IT WAS RECEIVING AN IDENT. THE APCH WAS COMPLETED IN VISUAL CONDITIONS. UPON INVESTIGATION WE FOUND THAT ALTHOUGH WE HAD 40 CHANNEL CTL HEADS INSTALLED IN OUR ACFT WE ONLY HAD 20 CHANNEL NAV RECEIVERS. WE HAVE BEEN TOLD THAT OTHER OPERATORS HAVE EXPERIENCED THE SAME PROBLEM.

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.