Regional Jet 700 ER/LR (CRJ700)
Flight Crew Air Transport Pilot (ATP)
Troubleshooting; Human-Machine Interface; Workload; Situational Awareness; Distraction
Aircraft Equipment Problem Critical; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Provided Assistance; Aircraft Equipment Problem Dissipated; Flight Crew Became Reoriented; Flight Crew FLC Overrode Automation; Flight Crew Requested ATC Assistance / Clarification
Aircraft
We were instructed to line up and wait Runway 25R LAX and informed that several aircraft would be crossing our runway down field. Once we were aligned on Runway 25R we verified both pilots DG's were in alignment and they were. Shortly after we [received] an EICAS MSG EFIS COMP HDG. We then realigned our DG'S as per our procedures. The EICAS MSG went away but then came back. Our headings were off by more than 10 degrees. We then realigned our headings to match the runway and elected to depart in DG mode as per our procedures due to the magnetic interference. Once cleared for takeoff we verified heading against runway both DG's matched. Our departure clearance was to fly the Loop 6 Departure DAG transition. Once established on the 235 degree heading of the departure awaiting clearance direct LAX VOR the autopilot was engaged. ATC then cleared us direct LAX comply with the LOOP 6 climb 15;000 FT. We the entered direct LAX and engaged NAV. The aircraft began left turn towards LAX. Once we completed loop eastbound back towards LAX aircraft kept turning left. The autopilot was then disengaged and wings rolled level. Once wings level then noticed that both DG's were more than 30 degrees different from Aircraft compass. Attempted to then regain accurate heading. ATC then called and asked what fix we were navigating to. They then cleared us direct DAG. We told them that both our DG's were off. They asked for our heading to compare against our track. Our heading was off more than 30 degrees. Once established direct DAG we were able to get both DG's aligned to correct heading and continued flight as normal. We may have deviated from the Loop 6 departure while trying to correct heading but was not informed of that by ATC.
This report contains no additional information.
After an EICAS EFIS COMP MAG alert while holding on the runway; the CRJ-700 crew took off in the DG Mode and discovered on the LAX LOOP 6 Departure that the heading remained 30 degrees in error until the aircraft was direct DAG.