MD-83
Flight Crew Air Transport Pilot (ATP)
Human-Machine Interface; Distraction; Situational Awareness; Workload; Troubleshooting
Aircraft Equipment Problem Critical
Flight Crew Requested ATC Assistance / Clarification; Flight Crew Returned To Departure Airport; General Declared Emergency; General Maintenance Action
Aircraft
After an aircraft swap; aircraft deplane due to Maintenance; a gate return with a second aircraft deplane due to Maintenance; [after] a total of 6-7 delays we departed. During the climb we started getting the Heading Comparator annunciator on the FMAs. As we would check and verified the headings the annunciator would go out and shortly come back. Looking in the QRH we could not find anything that would cover this issue. This issue became more frequent and climbing through FL22-FL23 the autopilot kicked off and map fail on the NDs. I took the controls and began hand flying the airplane while the First Officer tried to align the headings to get some instruments back. This would work for a couple of seconds and it would go out again. Due to the nature of the situation and being IMC we requested to return back to the departure airport. Since I had to use the Standby Compass to navigate we declared an emergency and requested headings and turns from ATC. We were vectored to the airport and landed without any further issues. Due to this event and earlier events the First Officer and I removed ourselves from further flying that day.
A MD-83 Instrument Comparator began alerting after takeoff so following numerous inflight realignment attempts; the autopilot disengagement and ND faults; an emergency was declared with a request for a no gyro vectors to the departure airport.