A flight crew on a nrs (navigational reference system) flight plan was issued a clearance direct to ...

Attributes
ACN	1157258
Time
Date	201403
Local Time Of Day	1201-1800
Place
Locale Reference	ZDV.ARTCC
State Reference	CO
Environment
Light	Dusk
Aircraft 1
Make Model Name	Large Transport Low Wing 2 Turbojet Eng
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Route In Use	Direct
Flight Plan	IFR
Component
Aircraft Component	FMS/FMC
Person 1
Function	First Officer Pilot Flying
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy Deviation - Track / Heading All Types

Narrative:

I was the pilot flying. Received a clearance shortly after level off to precede direct pgs. I entered it in the FMC; verified with non pilot flying (nfp) and executed. As workload permitted I added the fixes from the flight plan for abeam point monitoring; again verifying with nfp. (I used the plan mode on nav screen and saw no anomalies. (Abeam fixes were KD51U and KD42Q).over an hour later; ZDV complained that it appeared we were about 5 degrees off course to the north and asked us to verify. I re-entered pgs direct and found that the controller was correct. The abeam points were not in a straight line with the direct course. To my knowledge we followed correct procedures; however the abeam points were a few degrees off. The controller did not seem upset; nor were we aware of a conflict.since a long distance was involved; a few degrees of course change between points on the FMC did not alarm me. I thought the abeam points were using great circle course.

Original NASA ASRS Text

Title: A flight crew on a NRS (Navigational Reference System) flight plan was issued a clearance direct to a distant NAVAID then entered NRS abeam points which caused a five degree track deviation.

Narrative: I was the pilot flying. Received a clearance shortly after level off to precede direct PGS. I entered it in the FMC; verified with non pilot flying (NFP) and executed. As workload permitted I added the fixes from the flight plan for abeam point monitoring; again verifying with NFP. (I used the plan mode on Nav screen and saw no anomalies. (Abeam fixes were KD51U and KD42Q).Over an hour later; ZDV complained that it appeared we were about 5 degrees off course to the north and asked us to verify. I re-entered PGS direct and found that the Controller was correct. The abeam points were not in a straight line with the direct course. To my knowledge we followed correct procedures; however the abeam points were a few degrees off. The Controller did not seem upset; nor were we aware of a conflict.Since a long distance was involved; a few degrees of course change between points on the FMC did not alarm me. I thought the abeam points were using great circle course.

Data retrieved from NASA's ASRS site 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.

A flight crew on a nrs (navigational reference system) flight plan was issued a clearance direct to a distant NAVAID then entered nrs abeam points which caused a five degree track deviation.