EMB135 crew reports concerns with navigation accuracy during korry 3 STAR.

Attributes
ACN	726613
Time
Date	200702
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : eno.vortac
State Reference	DE
Altitude	msl single value : 19000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdc.artcc
Operator	common carrier : air carrier
Make Model Name	EMB ERJ 145 ER&LR
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	cruise : level
Route In Use	arrival star : korry3
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
ASRS Report	726613
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	aircraft equipment problem : less severe
Independent Detector	other controllera other flight crewa
Resolutory Action	none taken : anomaly accepted
Supplementary
Problem Areas	Aircraft
Primary Problem	Aircraft

Narrative:

This is my third report for this exact event. Between eno and skipy on the korry 3; ZDC asked if we were using FMS navigation. We responded affirmative and they reported that we were about 1 mi west of course paralleling the course. Magenta and green needles were both centered and LNAV was engaged using the FMS. I went to the 'FMS navigation:sensors:GPS position' page and noticed that the airplane was .7 mi west of the GPS position. I will keep submitting this same report every time this happens until I get an explanation of why this continues to occur. There is no action that we could have taken to prevent this type of deviation.

Original NASA ASRS Text

Title: EMB135 CREW RPTS CONCERNS WITH NAV ACCURACY DURING KORRY 3 STAR.

Narrative: THIS IS MY THIRD RPT FOR THIS EXACT EVENT. BTWN ENO AND SKIPY ON THE KORRY 3; ZDC ASKED IF WE WERE USING FMS NAV. WE RESPONDED AFFIRMATIVE AND THEY RPTED THAT WE WERE ABOUT 1 MI W OF COURSE PARALLELING THE COURSE. MAGENTA AND GREEN NEEDLES WERE BOTH CTRED AND LNAV WAS ENGAGED USING THE FMS. I WENT TO THE 'FMS NAV:SENSORS:GPS POS' PAGE AND NOTICED THAT THE AIRPLANE WAS .7 MI W OF THE GPS POS. I WILL KEEP SUBMITTING THIS SAME RPT EVERY TIME THIS HAPPENS UNTIL I GET AN EXPLANATION OF WHY THIS CONTINUES TO OCCUR. THERE IS NO ACTION THAT WE COULD HAVE TAKEN TO PREVENT THIS TYPE OF DEV.

Data retrieved from NASA's ASRS site as of January 2009 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.