Aircraft flies 10 degrees off course during SID departure from mco.

Attributes
ACN	357500
Time
Date	199701
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : orl
State Reference	FL
Altitude	msl bound lower : 10000 msl bound upper : 10000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : mco
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	climbout : intermediate altitude
Route In Use	departure sid : sid
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Experience	flight time last 90 days : 120 flight time total : 3600
ASRS Report	357500
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	non adherence : far non adherence : published procedure non adherence : clearance other spatial deviation
Independent Detector	other controllera
Resolutory Action	flight crew : returned to intended course or assigned course other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Our flight had intercepted and was tracking outbound on the orlando 338 degree radial on the mccoy 3 departure (needle centered, no flags). Departure control told us to turn right ? Degrees to rejoin the SID. I asked him what he showed our position to be. He replied '10 mi west of course.' our navigation equipment is set up in a way that only 1 navigation system may be viewed at a time. After selecting navigation #2 (we were using navigation #1), we noticed a 10 degree discrepancy between navigation #1 and navigation #2. However, after later comparisons of navs #1 and #2 using different navigation facilities, we noticed no discrepancies between the two. In reviewing the aircraft logbook, there have been numerous write-ups involving navs #1 and #2 in the ILS mode (ie, losing localizer signal accompanied by off flag). My crew had no reason to suspect a problem with the navigation equipment according to both the logbook and instrument indication.

Original NASA ASRS Text

Title: ACFT FLIES 10 DEGS OFF COURSE DURING SID DEP FROM MCO.

Narrative: OUR FLT HAD INTERCEPTED AND WAS TRACKING OUTBOUND ON THE ORLANDO 338 DEG RADIAL ON THE MCCOY 3 DEP (NEEDLE CENTERED, NO FLAGS). DEP CTL TOLD US TO TURN R ? DEGS TO REJOIN THE SID. I ASKED HIM WHAT HE SHOWED OUR POS TO BE. HE REPLIED '10 MI W OF COURSE.' OUR NAV EQUIP IS SET UP IN A WAY THAT ONLY 1 NAV SYS MAY BE VIEWED AT A TIME. AFTER SELECTING NAV #2 (WE WERE USING NAV #1), WE NOTICED A 10 DEG DISCREPANCY BTWN NAV #1 AND NAV #2. HOWEVER, AFTER LATER COMPARISONS OF NAVS #1 AND #2 USING DIFFERENT NAV FACILITIES, WE NOTICED NO DISCREPANCIES BTWN THE TWO. IN REVIEWING THE ACFT LOGBOOK, THERE HAVE BEEN NUMEROUS WRITE-UPS INVOLVING NAVS #1 AND #2 IN THE ILS MODE (IE, LOSING LOC SIGNAL ACCOMPANIED BY OFF FLAG). MY CREW HAD NO REASON TO SUSPECT A PROB WITH THE NAV EQUIP ACCORDING TO BOTH THE LOGBOOK AND INST INDICATION.

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.