Date: 201504
Local time of day: 1201-1800
Location: CLT.Airport, NC
Flight conditions: VMC
Weather elements / visibility: 10
Light: Daylight
Aircraft: Citation Excel (C560XL)
Operator: Corporate
Operating under: Part 91
Flight plan: IFR
Mission: Passenger
Flight phase: Descent
Airspace: Class B CLT
ATC / advisory: TRACON CLT
Aircraft component: FMS/FMC
Component problem: Malfunctioning
Reporter organization: Corporate
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Flight Instructor; Flight Crew Multiengine
Human factors: Human-Machine Interface; Confusion
Second reporter function: Captain; Pilot Flying
Anomaly: Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance
Detector: Person Flight Crew; Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Flight Crew Returned To Clearance
Contributing factors: Aircraft; Human Factors
Primary problem: Aircraft

Narrative: We were approaching CLT from the north on the IVANE5 arrival. Prior to starting the arrival; I visually checked the intersections as programmed in our UNS1Esp NAV radios. All appeared as it should have. We received a 'Descend Via' clearance as we started in the gate at the LYH fix. Due to weather; we were approved a deviation around some buildups at approximately the KELLS and MSTRD intersections. Our deviation was to the south east. Once clear of the weather; we were cleared back to intercept and rejoin the route. At this time I noticed the VNAV page did not display any of the crossing altitudes as depicted on the chart. As the fixes and altitudes were displayed in the flight plan; I spent some time getting the VNAV page to accept the crossing fixes while rejoining the arrival midway.As we approached the transition fix of IVANE; my captain (PF); noted there was not any routing after to indicate our next fix. The navigation unit appeared to be programmed as required for the ILS 23 approach as required by the STAR; but the transition legs were no longer displayed after I had reestablished the VNAV part of the route. It is unclear if this VNAV issue caused the NAV unit to dump the route after the IVANE fix. At this time; I attempted to right the error; and reselect the arrival route. As we are taught to 'AVIATE; NAVIGATE; COMMUNICATE;' I neglected to inform Charlotte of our NAV difficulties in a timely manner. The FP did follow the headings on the chart as best as possible; turning toward BABZE and BLNCO; as I struggled to reprogram the NAV. We were no more than a couple of miles past IVANE when Charlotte Approach gave us a heading and altitude plus a runway change to 18L. This took us off the STAR. The controller asked if we were on the IVANE5; to which we said yes. At that time; a short discussion of the benefits of assigning runways a greater distance from the airport took place. From that point on the approach and landing went well. Then as we cleared the runway the tower gave us a phone number to call; 'at our convenience;' and stated; 'Possible Pilot Deviation.' We did not call the number at that time; electing to ask questions of counsel before making the call.To reduce and/or eliminate the issue with the STAR and its programming; we are going back to school. Universal will be contacted to supply training advise for the universal NAV radios in relation to the 'descend via STAR' and to assure the unique runway transitions are displayed.Confess early: Get off the restricted route if the NAV radio isn't performing correctly. Involve ATC in corrective action.Further: all SID and STAR routes will be reviewed and visually confirmed by the crew before the initial entrance of the procedure. The option to refuse the procedure will also be utilized if there is a quick switch of arrivals and little time to reprogram the box.


Second narrative: Upon reporting direct MAYOS; were told to join IVANE5 Arrival; descend and maintain FL240; then Descend via SID. FMS NAV and VNAV confirmed with IVANE5 Arrival chart. Just prior to crossing IVANE the FMS's (both; synched) dumped NAV and VNAV data. MFD displayed no data beyond IVANE; autopilot leveled at 10;000 feet. I called this to attention of my First Officer (also a Captain). He immediately began reprogramming our FMS's. I input descent trim for lower; and the aircraft continued on last course (221 degrees) while I referred to the IVANE5 Arrival chart for NAV guidance to our next fix. As I did; BLNCO displayed on the MFD as our next fix. As I initiated a turn further left toward BLNCO; I questioned my FO; 'What about BABZE before BLNCO?' FO responded; we were already beyond BABZE. At that moment we were going to advise ATC; but Charlotte Approach called us first and asked if we had been issued the IVANE5; saying we looked 'high' (maybe he said 'hot' too). FO responded affirmative to the receipt of IVANE5; but said our FMS's had dumped our arrival data; adding that earlier runway assignment would benefit our programming. Controller agreed; gave us a 270 heading; changed runway to 18L; gave a lower descent altitude and airspeed reduction. At no time did we observe proximity traffic nor alerts via TCAS. Subsequent vectors resulted in a visual approach and landing on 18L.Upon clearing the runway; tower gave us a phone number to call when we had time; advising 'possible pilot deviation'. We were quite surprised. Subsequent conversation with the Charlotte Approach Facility Manager indicated that there was not time enough for the approach controller to advise the adjacent sector of our situation which led to an 'airspace violation'; and he had no discretion in reporting this to the FSDO. Upon discussing this event with our local POI (Principal Operations Inspector) at our FSDO; we were told this 'Data dump' scenario has occurred many times; especially after an aircraft has rejoined an Arrival after off course vectors.We have downloaded our FMS's data recordings and submitted them to our FMS manufacturer (Universal UNS1Esp) for evaluation and explanation. We must have confidence in our equipment; including our programing ability and the limitations of said equipment (procedures?). We certainly understand the seriousness of aircraft not complying with routing and altitudes. Recognition of our situation was near real-time. We attempted to immediately remedy our situation. We believed we would correct everything before we did. We thought; '...just a few more keystrokes...'. However; it took longer than we thought; and ATC called us before we called them. We will share this experience with our recurrent training provider to see what insights they may offer.Lessons learned: Be prepared. Always be ahead of the aircraft--especially subsequent fixes; courses; crossing restrictions. Always have pertinent charting readily available. Advise ATC immediately of all reduced capabilities. When a similar situation develops; we will immediately advise ATC prior to commencing any time consuming resolutions in order to prevent any potential deviation; conflict or violation.


Synopsis: CE560 flight crew reports losing NAV capability shortly after returning to the IVANE5 RNAV from deviations around weather. ATC is not advised in a timely manner and Radar vectors to a different runway are issued. The crew is asked to call Approach Control at their convenience.