A md-83 instrument comparator began alerting after takeoff so following numerous inflight realignmen...

Narrative:

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.

Original NASA ASRS Text

Title: 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.

Narrative: 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.

Data retrieved from NASA's ASRS site as of July 2013 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.

Attributes
ACN	1098814
Time
Date	201307
Local Time Of Day	1801-2400
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Make Model Name	MD-83
Operating Under FAR Part	Part 121
Flight Phase	Climb
Flight Plan	IFR
Component
Aircraft Component	Positional / Directional Sensing
Person 1
Function	Captain Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Aircraft Equipment Problem Critical

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.