MD83 crew experienced FMS navigation anomalies departing lax. Way point pevee moves to a position ah...

Narrative:

On departure from lax holtz 9 RNAV we were cleared direct pevee while we were near weilr. Direct pevee selected; engaged and navigation track noted; autopilot flying. About 2 miles from pevee I noted I had lost the magenta line on the 10 mile scale; the first officer still had a magenta line to pevee; navigation track still indicated and aircraft tracking to pevee. Over pevee first officer track line disappeared aircraft began a turn in the correct direction but more than would be expected; during the turn; pevee jumped to our 1 o'clock position on our screen and about 7 miles away. I notified ATC and requested a vector to holtz. All normal for rest of flight told each ATC of possible issue; and called dispatch for concurrence of continued flight using RNAV; VOR; and ATC vectors.

Original NASA ASRS Text

Title: MD83 crew experienced FMS navigation anomalies departing LAX. Way point PEVEE moves to a position ahead of the aircraft after initially disappearing when it is over flown. ATC assistance is requested but no further anomalies are detected for the remainder of the flight.

Narrative: On departure from LAX HOLTZ 9 RNAV we were cleared direct PEVEE while we were near WEILR. Direct PEVEE selected; engaged and NAV track noted; autopilot flying. About 2 miles from PEVEE I noted I had lost the magenta line on the 10 mile scale; the First Officer still had a magenta line to PEVEE; NAV track still indicated and aircraft tracking to PEVEE. Over PEVEE First Officer track line disappeared aircraft began a turn in the correct direction but more than would be expected; during the turn; PEVEE jumped to our 1 o'clock position on our screen and about 7 miles away. I notified ATC and requested a vector to HOLTZ. All normal for rest of flight told each ATC of possible issue; and called Dispatch for concurrence of continued flight using RNAV; VOR; and ATC vectors.

Data retrieved from NASA's ASRS site as of April 2012 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.

Attributes
ACN	983022
Time
Date	201112
Local Time Of Day	0601-1200
Place
Locale Reference	LAX.Tower
State Reference	CA
Environment
Flight Conditions	VMC
Aircraft 1
Make Model Name	MD-83
Operating Under FAR Part	Part 121
Flight Phase	Climb
Component
Aircraft Component	FMS/FMC
Person 1
Function	Pilot Not Flying
Experience	Flight Crew Total 14000
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Procedural Clearance Deviation - Track / Heading All Types

MD83 crew experienced FMS navigation anomalies departing lax. Way point pevee moves to a position ahead of the aircraft after initially disappearing when it is over flown. ATC assistance is requested but no further anomalies are detected for the remainder of the flight.