<< >> NASA ASRS Report 439311, June 1999

Captain of a cpr learjet 35 complaint of automatic WX reporting transmitter frequency overlap causing difficulty in hearing airport WX at high altitude 75 mi away from destination airport.

Attributes
ACN	439311
Time
Date	199906
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : 1o6.airport
State Reference	CA
Altitude	msl single value : 24000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zoa.artcc
Operator	general aviation : corporate
Make Model Name	Learjet 35
Operating Under FAR Part	Part 91
Flight Phase	descent : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	company : corporate
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : cfi
Experience	flight time last 90 days : 60 flight time total : 8000 flight time type : 200
ASRS Report	439311
Person 2
Affiliation	company : corporate
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument pilot : multi engine
Events
Anomaly	other anomaly other
Independent Detector	other flight crewa
Resolutory Action	none taken : anomaly accepted
Supplementary
Problem Areas	Weather Airport
Primary Problem	Airport
Situations
Airport	other physical facility

Narrative:

This is an ongoing problem. While returning from alaska to a private airport south of red bluff, ca, I listen to the red bluff, ca, AWOS/ASOS on 120.775 MHZ to obtain the local WX/winds. In attempting to do this, I always receive interference from another station idented as 'mount shasta' on the same frequency. This makes it impossible to receive the rbl broadcast until very close to red bluff. It is important to receive this data early, prior to initiating an approach, as winds, sky conditions, and surface temperature are needed early on. 1 transmitter's frequency or the other should be changed. Callback conversation with reporter revealed the following information: reporter stated that the ASOS transmitter is heard ok when in close to the airport and away from the other ASOS transmitter. However, he believes that this problem could be corrected easily by changing the frequency on one of the transmitters.

Related reports:

• An MD11 on vectors for approach at vabb deviated from assign...

	Enter your search terms Submit search form
	Web www.37000feet.com

Original NASA ASRS Text

Title: CAPT OF A CPR LEARJET 35 COMPLAINT OF AUTOMATIC WX RPTING XMITTER FREQ OVERLAP CAUSING DIFFICULTY IN HEARING ARPT WX AT HIGH ALT 75 MI AWAY FROM DEST ARPT.

Narrative: THIS IS AN ONGOING PROB. WHILE RETURNING FROM ALASKA TO A PVT ARPT S OF RED BLUFF, CA, I LISTEN TO THE RED BLUFF, CA, AWOS/ASOS ON 120.775 MHZ TO OBTAIN THE LCL WX/WINDS. IN ATTEMPTING TO DO THIS, I ALWAYS RECEIVE INTERFERENCE FROM ANOTHER STATION IDENTED AS 'MOUNT SHASTA' ON THE SAME FREQ. THIS MAKES IT IMPOSSIBLE TO RECEIVE THE RBL BROADCAST UNTIL VERY CLOSE TO RED BLUFF. IT IS IMPORTANT TO RECEIVE THIS DATA EARLY, PRIOR TO INITIATING AN APCH, AS WINDS, SKY CONDITIONS, AND SURFACE TEMP ARE NEEDED EARLY ON. 1 XMITTER'S FREQ OR THE OTHER SHOULD BE CHANGED. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT THE ASOS XMITTER IS HEARD OK WHEN IN CLOSE TO THE ARPT AND AWAY FROM THE OTHER ASOS XMITTER. HOWEVER, HE BELIEVES THAT THIS PROB COULD BE CORRECTED EASILY BY CHANGING THE FREQ ON ONE OF THE XMITTERS.

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.