LORAN not giving accurate information, pilot requests DF steer.

Attributes
ACN	257479
Time
Date	199311
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : duj
State Reference	PA
Altitude	msl bound lower : 3500 msl bound upper : 3500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	general aviation : personal
Make Model Name	Small Aircraft, High Wing, 1 Eng, Fixed Gear
Flight Phase	cruise other
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : private
Experience	flight time last 90 days : 19 flight time total : 390 flight time type : 350
ASRS Report	257479
Person 2
Affiliation	government : faa
Function	other personnel other
Qualification	other
Events
Anomaly	aircraft equipment problem : less severe other spatial deviation
Independent Detector	other flight crewa
Resolutory Action	flight crew : became reoriented
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Planned flight from westmoreland county (lbe) to bradford (bfd), PA. Flight proceeded normally until past dubois (duj). Received conflicting information from LORAN and VOR which I allowed to cause me to become uncertain of my position. Later determined LORAN signal to noise ratios (snr) had deteriorated to less than 35, 7, and 9. I am aware of a problem with LORAN signals at dawn and twilight, but did not expect a problem about XA00 pm although the sun is lower on the horizon this time of yr. In addition, the VOR flag did not fully appear causing me to doubt its information. Although I was aware of my position generally and had over 2 hours of fuel remaining, I decided to be conservative and ask the dubois FSS for a direction-finding steer to their airport. The DF steer and my landing were accomplished without incident. I returned to lbe navigating by pilotage, also without incident. Note that I use a portable LORAN with a windshield mounted antenna which had been very reliable. I plan the following correction action: monitor LORAN snr periodically in-flight. Have the VOR and its installation thoroughly checked by an authorized electronics shop.

Original NASA ASRS Text

Title: LORAN NOT GIVING ACCURATE INFO, PLT REQUESTS DF STEER.

Narrative: PLANNED FLT FROM WESTMORELAND COUNTY (LBE) TO BRADFORD (BFD), PA. FLT PROCEEDED NORMALLY UNTIL PAST DUBOIS (DUJ). RECEIVED CONFLICTING INFO FROM LORAN AND VOR WHICH I ALLOWED TO CAUSE ME TO BECOME UNCERTAIN OF MY POS. LATER DETERMINED LORAN SIGNAL TO NOISE RATIOS (SNR) HAD DETERIORATED TO LESS THAN 35, 7, AND 9. I AM AWARE OF A PROB WITH LORAN SIGNALS AT DAWN AND TWILIGHT, BUT DID NOT EXPECT A PROB ABOUT XA00 PM ALTHOUGH THE SUN IS LOWER ON THE HORIZON THIS TIME OF YR. IN ADDITION, THE VOR FLAG DID NOT FULLY APPEAR CAUSING ME TO DOUBT ITS INFO. ALTHOUGH I WAS AWARE OF MY POS GENERALLY AND HAD OVER 2 HRS OF FUEL REMAINING, I DECIDED TO BE CONSERVATIVE AND ASK THE DUBOIS FSS FOR A DIRECTION-FINDING STEER TO THEIR ARPT. THE DF STEER AND MY LNDG WERE ACCOMPLISHED WITHOUT INCIDENT. I RETURNED TO LBE NAVING BY PILOTAGE, ALSO WITHOUT INCIDENT. NOTE THAT I USE A PORTABLE LORAN WITH A WINDSHIELD MOUNTED ANTENNA WHICH HAD BEEN VERY RELIABLE. I PLAN THE FOLLOWING CORRECTION ACTION: MONITOR LORAN SNR PERIODICALLY INFLT. HAVE THE VOR AND ITS INSTALLATION THOROUGHLY CHKED BY AN AUTHORIZED ELECTRONICS SHOP.

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.