Narrative:

We were enroute to vgt at FL180. Our assigned route was pmd dag.KEPEC2. Approximately ten miles from dag ATC changed the route to dag V587 bld direct. For some unknown reason the universal FMS in our aircraft was not allowing us to input V587 from dag. The chart clearly showed the intersection. The avionics were switched to ground based navaids which allowed us to navigate V587. The remaining fixes on the route (whigg boach creso disca) were entered into the FMS allowing RNAV to be reengaged. The fixes were depicted in their respective positions along the airway when looking at the mfd. Just as this task was being completed ATC cleared us to cross whigg at 13;000 ft. The crossing was entered into the VNAV function of the FMS properly. The FMS showed 40 miles to whigg. The aircraft was actually much closer to whigg. The controller called after a few minutes to confirm we could make the crossing. I stated we could; believing we were still over 20 miles from whigg as the FMS showed. When the controller called to confirm the crossing I began to suspect our position information was incorrect in the FMS and began an immediate descent. A moment later the controller called to tell us we were over whigg. We were descending through 17;500 ft at 2;500 FPM. I explained briefly that we had FMS difficulties and asked for a descent vector. We were told to continue our descent on course. No traffic conflict occurred. It never was determined why the FMS would not allow the input of the airway from dag. It functioned properly on flights before and after the event.

Related reports:

Google
 

Original NASA ASRS Text

Title: A P180 Captain reported inability to change his arrival routing into VGT from the KEPEC2 to DAG V587 BLD as assigned by ATC. The universal FMS would not accept V587 after DAG; although it would accept the waypoints along V587. A crossing restriction issued for WHIGG was missed due to inaccurate distance information provided by the FMC.

Narrative: We were enroute to VGT at FL180. Our assigned route was PMD DAG.KEPEC2. Approximately ten miles from DAG ATC changed the route to DAG V587 BLD direct. For some unknown reason the universal FMS in our aircraft was not allowing us to input V587 from DAG. The chart clearly showed the intersection. The avionics were switched to ground based NAVAIDs which allowed us to navigate V587. The remaining fixes on the route (WHIGG BOACH CRESO DISCA) were entered into the FMS allowing RNAV to be reengaged. The fixes were depicted in their respective positions along the airway when looking at the MFD. Just as this task was being completed ATC cleared us to cross WHIGG at 13;000 FT. The crossing was entered into the VNAV function of the FMS properly. The FMS showed 40 miles to WHIGG. The aircraft was actually much closer to WHIGG. The Controller called after a few minutes to confirm we could make the crossing. I stated we could; believing we were still over 20 miles from WHIGG as the FMS showed. When the Controller called to confirm the crossing I began to suspect our position information was incorrect in the FMS and began an immediate descent. A moment later the Controller called to tell us we were over WHIGG. We were descending through 17;500 FT at 2;500 FPM. I explained briefly that we had FMS difficulties and asked for a descent vector. We were told to continue our descent on course. No traffic conflict occurred. It never was determined why the FMS would not allow the input of the airway from DAG. It functioned properly on flights before and after the event.

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.