Flight crew of C500 receives faulty information from their FMS and revert to 'slant a' navigation.

Attributes
ACN	682243
Time
Date	200512
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : dts.airport
State Reference	FL
Altitude	msl single value : 20000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zjx.artcc
Operator	general aviation : corporate
Make Model Name	Citation I
Operating Under FAR Part	Part 91
Navigation In Use	other other vortac
Flight Phase	climbout : intermediate altitude
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	company : corporate
Function	flight crew : captain oversight : pic
Experience	flight time last 90 days : 70 flight time total : 4800 flight time type : 500
ASRS Report	682243
Person 2
Affiliation	company : corporate
Function	flight crew : first officer
Events
Anomaly	aircraft equipment problem : less severe non adherence : clearance other spatial deviation
Independent Detector	other controllera
Resolutory Action	controller : issued advisory flight crew : overcame equipment problem flight crew : overrode automation
Supplementary
Problem Areas	Flight Crew Human Performance Aircraft
Primary Problem	Aircraft

Narrative:

Aircraft departed destin; fl (dts). Elgin departure sent us direct crestview VOR then J-2. Our aircraft is equipped with a kns 660 FMS. Direct crestview was selected and an on-course heading of 263 degrees was displayed. Departure then called us and told us crestview was due north of our position. We rechked the FMS and confirmed crestview was selected. There were no flags or red X's on FMS or EFIS. Ground speed readout showed 650 KTS. 115.90 was entered and center notified that we were a C500/a. Kns 660 is a VOR/navigation based FMS. There is no GPS input and information on readout was incorrect -- speed; heading; etc. I will no longer trust one form of navigation -- flag or no flag. This is my first NASA report in 15 yrs of flying.

Original NASA ASRS Text

Title: FLT CREW OF C500 RECEIVES FAULTY INFO FROM THEIR FMS AND REVERT TO 'SLANT A' NAV.

Narrative: ACFT DEPARTED DESTIN; FL (DTS). ELGIN DEP SENT US DIRECT CRESTVIEW VOR THEN J-2. OUR ACFT IS EQUIPPED WITH A KNS 660 FMS. DIRECT CRESTVIEW WAS SELECTED AND AN ON-COURSE HDG OF 263 DEGS WAS DISPLAYED. DEP THEN CALLED US AND TOLD US CRESTVIEW WAS DUE N OF OUR POS. WE RECHKED THE FMS AND CONFIRMED CRESTVIEW WAS SELECTED. THERE WERE NO FLAGS OR RED X'S ON FMS OR EFIS. GND SPD READOUT SHOWED 650 KTS. 115.90 WAS ENTERED AND CTR NOTIFIED THAT WE WERE A C500/A. KNS 660 IS A VOR/NAV BASED FMS. THERE IS NO GPS INPUT AND INFO ON READOUT WAS INCORRECT -- SPD; HDG; ETC. I WILL NO LONGER TRUST ONE FORM OF NAV -- FLAG OR NO FLAG. THIS IS MY FIRST NASA RPT IN 15 YRS OF FLYING.

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.