Situational Awareness
Aircraft Equipment Problem Less Severe; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance; Flight Crew Became Reoriented; Flight Crew Returned To Clearance
Aircraft; Human Factors
Somehow the FMS kicked out several fixes that were previously in the flight plan route as both the Captain and I checked the route and all fixes on the ground before the flight. All fixes were there before we departed. As we were climbing we were assigned a new ATC frequency and the controller said he was showing us 2 miles off of our filed course; that's all he said then he passed us over to another controller and he said that he was showing us 3 miles off course; we then asked for Direct to STL as that was the fix we were going to on J134; that was approved with no issues. We got out the paper chart to verify proper course and fixes along with the filed flight plan and legs on Flight release. It seems that the FMS somehow kicked out several fixes on J134. Both the Captain and I checked all of the fixes in the FMS with the flight release and PDC on the ground before the flight and all fixes were in the FMS.
The crew verified all FMS fixes in the flight plan route prior to departure. During the climb out ATC advised the crew of a track deviation. The crew requested and received a new clearance for direct routing.