Narrative:

I was flying the MARWI1 arrival [stj transition] into omaha for a landing on [runway] 14L; coupled to the autopilot in navigation mode. After crossing marwi; we tracked 300 to swaab. After swaab; the arrival requires flying a heading of 320 [and] then expect radar vectors to final approach course. However; I mistakenly followed the guidance of my GNS-500 in navigation mode which continued past swaab for approximately 7 miles direct to the airport (oma) until ATC called with a heading of 320; vectors to the final approach course. I repeated back the instruction; changed the autopilot mode controller to heading mode; and turned to a heading of 320. Seconds later; a different controller advised me of my mistake. The flight was continued and concluded with no further incident. The time of the incident was a higher workload situation. We were preparing for the landing; checking for traffic ahead and the pilot not flying was contacting the FBO for our arrival. We discussed having the field in sight from 30-35 miles away and announced it to omaha approach. We had briefed the arrival but as time elapsed; we forgot about flying the heading after swaab and simply followed the GPS.I believe that there are several contributing factors to this mistake. First; the garmin GNS-500 has no way of navigating a heading. Unless the procedure involves 'tracking' a heading; it will navigate directly to the airport. Secondly; the inconsistency of arrival procedures from airport to airport. We routinely fly [an arrival into another airport that calls for a] 'track' of 346. Our GPS can comply with this routing whereas it can not fly a heading. If all arrivals would incorporate 'tracking' headings instead of 'flying' headings; they would be consistent and wouldn't require the changing of the autopilot mode control. Thirdly; while we weren't below 10;000 ft; we allowed ourselves to be distracted with other tasks (calling the FBO) while in a high workload environment.while I can't do anything to change the way my autopilot works or the way the arrivals are built; I can change how and when we call the FBO and handle other non-critical tasks. I will discuss with the flight crew a new procedure for handling those tasks while further out from our destination (50 miles).

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Original NASA ASRS Text

Title: C525 Captain reported deviating from an arrival into OMA in part because his FMS cannot fly headings; only tracks.

Narrative: I was flying the MARWI1 arrival [STJ Transition] into Omaha for a landing on [Runway] 14L; coupled to the autopilot in NAV mode. After crossing MARWI; we tracked 300 to SWAAB. After SWAAB; the arrival requires flying a heading of 320 [and] then expect radar vectors to final approach course. However; I mistakenly followed the guidance of my GNS-500 in NAV mode which continued past SWAAB for approximately 7 miles direct to the airport (OMA) until ATC called with a heading of 320; vectors to the final approach course. I repeated back the instruction; changed the autopilot mode controller to heading mode; and turned to a heading of 320. Seconds later; a different Controller advised me of my mistake. The flight was continued and concluded with no further incident. The time of the incident was a higher workload situation. We were preparing for the landing; checking for traffic ahead and the pilot not flying was contacting the FBO for our arrival. We discussed having the field in sight from 30-35 miles away and announced it to Omaha Approach. We had briefed the arrival but as time elapsed; we forgot about flying the heading after SWAAB and simply followed the GPS.I believe that there are several contributing factors to this mistake. First; the Garmin GNS-500 has no way of navigating a heading. Unless the procedure involves 'tracking' a heading; it will navigate directly to the airport. Secondly; the inconsistency of arrival procedures from airport to airport. We routinely fly [an arrival into another airport that calls for a] 'track' of 346. Our GPS can comply with this routing whereas it can not fly a heading. If all arrivals would incorporate 'tracking' headings instead of 'flying' headings; they would be consistent and wouldn't require the changing of the autopilot mode control. Thirdly; while we weren't below 10;000 FT; we allowed ourselves to be distracted with other tasks (calling the FBO) while in a high workload environment.While I can't do anything to change the way my autopilot works or the way the arrivals are built; I can change how and when we call the FBO and handle other non-critical tasks. I will discuss with the flight crew a new procedure for handling those tasks while further out from our destination (50 miles).

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.