Citation X (C750)
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Critical
Flight Crew Overcame Equipment Problem
Aircraft
During LGA 4 Whitestone Climb departure it became immediately apparent that AHRS headings had both malfunctioned and were 30-45 degrees off from each other. NAV information was extremely unreliable. DG fast slave did not work on either AHRS and autopilot could not be used. Magnetic compass was only immediate heading source. When ATC cleared us on a heading it was way off due to map error. LRP and HVQ VOR's were given but again displayed info was erroneous and direct course could not be flown even with green needles. Finally at higher altitudes and in smooth air; magnetic compass settled down enough to steer a reasonably accurate heading. No TCAS alerts were received.
[Narrative 2 had no additional information]
A CE-750 flight crew reported AHRS heading information was invalid on the LGA Whitestone climb. DG fast slave did not work; and all navigation information was inaccurate until the AHRS corrected itself at cruise altitude.