Narrative:

I was being vectored from the north to runway 36L from a left downwind and assigned the GPS 36L since runway 36R and its ILS were out of service. I twice attempted to load the GPS 36L approach in the GNS-xls and was unsuccessful since it was not listed. I am unsure why this was the case. I informed ATC that I could not accept the GPS 36L approach who then assigned me to the VOR/DME 36L and I set up that approach. As I was vectored into a base leg of 90 degrees to intercept the final approach course; I checked the display on the co-pilot HSI to confirm that it agreed with the pilot's HSI. At this time I noticed that the copilot HSI indicated a heading of 150 degrees while the pilot's HSI indicated the assigned heading of 90 degrees. There were no error indications on any of my flight instruments. I informed ATC that I had an instrument problem and because there was a lot of traffic landing on the parallel runway to the east; runway 35R; I asked for vectors to break off the approach so that I would not interfere with landing traffic on the east runway. I was very concerned that I might have lost situational awareness not being sure exactly what heading I had been on and would cause a conflict with landing traffic on the parallel runway. ATC said I was a mile west of my final approach course and was very helpful and gave me vectors back to the west and eventually set me up for an uneventful landing on 35R.the error chain had started when I was unable to load the originally assigned GPS approach and was elevated when I recognized the failure of the copilot heading which repeats on the pilot side RMI; which we are trained to use as the backup heading source. There simply was not enough time to confirm heading; and be sure I was not entering the landing traffic flow on the parallel runway. With the clarity of hindsight; I could have confirmed my pilot side heading with the wet compass; but in my ten years of recurrent training; I have never been given such a failure scenario; and it did not occur to me quickly enough. Given the turbulence and the strong crosswind; the wet compass would probably have given an inconclusive confirmation anyway. I think I did the proper action under the circumstances and alerted ATC to the problem which allowed them to assist in preventing a conflict. It is possible also that the avionics in the CE525 has a weakness in that no error alerting was observed to indicate that one compass system was inoperative; which meant that I didn't know how long the right side compass system had been stuck at 150 degrees; and that the pilot's side was in fact correct.

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Original NASA ASRS Text

Title: An IMC CE525 single Pilot on a VOR/DME approach vector noticed that the First Officer side compass was frozen; so he was uncertain about his actual heading and requested ATC's assistance.

Narrative: I was being vectored from the north to Runway 36L from a left downwind and assigned the GPS 36L since Runway 36R and its ILS were out of service. I twice attempted to load the GPS 36L approach in the GNS-XLS and was unsuccessful since it was not listed. I am unsure why this was the case. I informed ATC that I could not accept the GPS 36L approach who then assigned me to the VOR/DME 36L and I set up that approach. As I was vectored into a base leg of 90 degrees to intercept the final approach course; I checked the display on the co-pilot HSI to confirm that it agreed with the pilot's HSI. At this time I noticed that the copilot HSI indicated a heading of 150 degrees while the pilot's HSI indicated the assigned heading of 90 degrees. There were no error indications on any of my flight instruments. I informed ATC that I had an instrument problem and because there was a lot of traffic landing on the parallel runway to the east; Runway 35R; I asked for vectors to break off the approach so that I would not interfere with landing traffic on the east runway. I was very concerned that I might have lost situational awareness not being sure exactly what heading I had been on and would cause a conflict with landing traffic on the parallel runway. ATC said I was a mile west of my final approach course and was very helpful and gave me vectors back to the west and eventually set me up for an uneventful landing on 35R.The error chain had started when I was unable to load the originally assigned GPS approach and was elevated when I recognized the failure of the copilot heading which repeats on the pilot side RMI; which we are trained to use as the backup heading source. There simply was not enough time to confirm heading; and be sure I was not entering the landing traffic flow on the parallel runway. With the clarity of hindsight; I could have confirmed my pilot side heading with the wet compass; but in my ten years of recurrent training; I have never been given such a failure scenario; and it did not occur to me quickly enough. Given the turbulence and the strong crosswind; the wet compass would probably have given an inconclusive confirmation anyway. I think I did the proper action under the circumstances and alerted ATC to the problem which allowed them to assist in preventing a conflict. It is possible also that the avionics in the CE525 has a weakness in that no error alerting was observed to indicate that one compass system was inoperative; which meant that I didn't know how long the right side compass system had been stuck at 150 degrees; and that the pilot's side was in fact correct.

Data retrieved from NASA's ASRS site as of April 2012 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.