Narrative:

This flight was conducted in one of our new aircraft which is ahrs [attitude and heading reference system] equipped. Weather conditions were VMC at the field and throughout the new york area. The aircraft was light with only 36 passengers on board. We were cleared via the la guardia four departure off runway 13; whitestone climb. Per the departure procedure the initial assigned altitude was 5;000 ft. Prior to departure we were cleared to 'line up and wait' on runway 13; despite this area having known magnetic anomalies. As we waited on the runway there were no messages posted to the EICAS and no flags on either pfd. The heading bugged on the pfd's matched with the known runway heading. The ahrs system was in magnetic mode. Since everything appeared to be normal we did not switch to dg mode. The tower released us for departure and the takeoff roll was unremarkable. Once airborne and passing through about 200 ft; the master caution EFIS comp mon posted on the EICAS and the amber heading flag appeared on the first officer's pfd. At 400 ft the captain turned to a heading of 180 degrees and at 600 ft the autopilot was engaged. At 2.5 DME off of lga we turned to a heading of 40 degrees and once established on that heading accelerated to 250 KTS. The aircraft was 'cleaned up' per standard operating procedures. Established in the climb we turned our attention to the non-normal procedures for EFIS comp mon. Given that the aircraft was light our rate of climb was rapid. ATC cleared us to 12;000 ft which was set in the altitude pre selector. As we tried work through the non-normal procedures it became apparent that none of the 3 compasses were in agreement. The standby compass's status was questionable as the high rate of climb and turns required in the departure seemed to keep it from rotating smoothly. Distracted and perplexed by this; neither pilot realized that the auto pilot had captured the initial altitude of 5;000 ft at the same time that we were cleared to 12;000 ft. The aircraft leveled off and started to accelerate. The first officer was the first to recognize the trending increase in airspeed and called it out and the captain immediately retarded the throttles. The airspeed had increased to about 285 KTS. Simultaneously; ATC again requested that we climb to 12;000 ft. The captain complied with ATC's request which again resulted in a high rate of climb. Once again this seemed to give the stand by compass some issues. In the climb to 12;000 ft we were further cleared to 15;000 ft. Once level at 15;000 ft things settled down enough to complete the non-normal procedures and soon there after we were cleared direct to biggy intersection to join our flight plan route. The remainder of the flight was unremarkable. Without question we exceeded the airspeed limitation of 250 KTS when the aircraft leveled off at 5;000 ft. But I also have concerns that given the fact that we had three different compass readings in the cockpit; on a departure that was heading dependent; we may have also failed to comply with the heading requirements outlined in the SID. There are two things that I feel could have been done differently that would have likely avoided this event to begin with and could have helped us out once we were in the air. First it seems that despite the fact that we had no issues during our time on runway 13; given its history of magnetic anomalies we should have taken off in dg mode. Second; once airborne with our exact direction of flight in question; it would have been appropriate to alert ATC of our situation and seek their assistance to insure our compliance with the directional aspect of the SID.

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Original NASA ASRS Text

Title: A CRJ-900 flight crew experienced AHRS heading anomalies after taking off from Runway 13 at LGA following a period of LUAW. While assessing the heading issue; the aircraft leveled at their initial cleared altitude of 5;000 FT and the airspeed increased to approximately 285 KTS before they recommenced their climb to 12;000 FT as previously cleared by Departure. The approach end of Runway 13 northwest of the intersection with 04-22 is charted as susceptible to magnetic anomalies and was likely the progenitor of the event.

Narrative: This flight was conducted in one of our new aircraft which is AHRS [Attitude and Heading Reference System] equipped. Weather conditions were VMC at the field and throughout the New York area. The aircraft was light with only 36 passengers on board. We were cleared via the La Guardia Four Departure off Runway 13; Whitestone Climb. Per the departure procedure the initial assigned altitude was 5;000 FT. Prior to departure we were cleared to 'line up and wait' on Runway 13; despite this area having known magnetic anomalies. As we waited on the runway there were no messages posted to the EICAS and no flags on either PFD. The heading bugged on the PFD's matched with the known runway heading. The AHRS system was in MAG mode. Since everything appeared to be normal we did not switch to DG mode. The Tower released us for departure and the takeoff roll was unremarkable. Once airborne and passing through about 200 FT; the master caution EFIS COMP MON posted on the EICAS and the amber HDG flag appeared on the First Officer's PFD. At 400 FT the Captain turned to a heading of 180 degrees and at 600 FT the autopilot was engaged. At 2.5 DME off of LGA we turned to a heading of 40 degrees and once established on that heading accelerated to 250 KTS. The aircraft was 'cleaned up' per standard operating procedures. Established in the climb we turned our attention to the non-normal procedures for EFIS COMP MON. Given that the aircraft was light our rate of climb was rapid. ATC cleared us to 12;000 FT which was set in the altitude pre selector. As we tried work through the non-normal procedures it became apparent that none of the 3 compasses were in agreement. The standby compass's status was questionable as the high rate of climb and turns required in the departure seemed to keep it from rotating smoothly. Distracted and perplexed by this; neither pilot realized that the auto pilot had captured the initial altitude of 5;000 FT at the same time that we were cleared to 12;000 FT. The aircraft leveled off and started to accelerate. The First Officer was the first to recognize the trending increase in airspeed and called it out and the Captain immediately retarded the throttles. The airspeed had increased to about 285 KTS. Simultaneously; ATC again requested that we climb to 12;000 FT. The Captain complied with ATC's request which again resulted in a high rate of climb. Once again this seemed to give the stand by compass some issues. In the climb to 12;000 FT we were further cleared to 15;000 FT. Once level at 15;000 FT things settled down enough to complete the non-normal procedures and soon there after we were cleared direct to BIGGY Intersection to join our flight plan route. The remainder of the flight was unremarkable. Without question we exceeded the airspeed limitation of 250 KTS when the aircraft leveled off at 5;000 FT. But I also have concerns that given the fact that we had three different compass readings in the cockpit; on a departure that was heading dependent; we may have also failed to comply with the heading requirements outlined in the SID. There are two things that I feel could have been done differently that would have likely avoided this event to begin with and could have helped us out once we were in the air. First it seems that despite the fact that we had no issues during our time on Runway 13; given its history of magnetic anomalies we should have taken off in DG mode. Second; once airborne with our exact direction of flight in question; it would have been appropriate to alert ATC of our situation and seek their assistance to insure our compliance with the directional aspect of the SID.

Data retrieved from NASA's ASRS site 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.