Date: 201305
Local time of day: 1201-1800
Location: ATL.Airport, GA
Light: Daylight
Aircraft: Regional Jet 200 ER/LR (CRJ200)
Operator: Air Carrier
Operating under: Part 121
Flight phase: Taxi
ATC / advisory: Ground ATL
Aircraft component: AHRS/ND
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Second reporter function: Pilot Not Flying; First Officer
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Automation Aircraft Other Automation
When detected: Taxi
Result: Aircraft Equipment Problem Dissipated; Flight Crew Took Evasive Action
Contributing factors: Aircraft; Airport
Primary problem: Ambiguous

Narrative: We were cleared to taxi into position and hold for wake turbulence due to prior heavy aircraft departure. Due to the large amount of rebar used in the new runway addition on 27R; we received a nuisance fault message. We told the Tower that we could not accept a takeoff clearance and asked to taxi off of the runway. The fault cleared before we exited the runway. We got back into line and departed a short time later without any abnormalities. The thrust levers were never advanced for the purpose of takeoff. In hindsight; I should have contacted Maintenance Control and possibly documented the nuisance fault. Being that the fault cleared itself so quickly; we did believe that it was an issue. Since the thrust levers were never advanced for the purpose of takeoff; we did not feel the need to notify the company via filing a report.


Second narrative: We were given a taxi into position and hold [Runway] 27R at LC clearance by Atlanta Tower. After we taxied into position and held on the runway; aircraft gave us an 'EFIS COMP MON' caution message.......and 3 red flags appeared on Captain's PFD. The flags continued to remain on Captain's PFD as we held on Runway 27R. After discussing issue amongst one another; Captain made decision not to continue; and asked me to inform Atlanta Tower that we would need to exit the runway. Captain advanced thrust levers to taxi aircraft off of runway as ATC granted our clearance to exit and get back in line. As we taxied forward; Atlanta Tower asked us if we needed assistance; I replied negative and Captain explained to Atlanta Tower that the rebar in the runway caused us to have interference in our flight instruments. After taxiing off runway; Captain's PFD was cleared of any red flags; and 'EFIS COMP MON' caution message cleared as well. Thrust levers were never brought to the full take off power position; as decision to taxi off runway was made upon discovery of red flags. We got back in line and when it was our turn; ATC cleared us for takeoff Runway 27R; rest of flight was uneventful.


Synopsis: CRJ200 flight crew reports being cleared to line up and wait on Runway 27R at ATL; then noting an 'EFIS COMP MON' caution message....and 3 red flags on Captain's PFD. The crew taxies clear of the runway and the problem disappears. The next attempt at takeoff is successful. The Captain believes the rebar in the new runway extension is causing interference with the aircraft compass system [AHRS].