Citation Excel (C560XL)
Flight Crew Air Transport Pilot (ATP)
Confusion; Distraction; Situational Awareness; Time Pressure; Workload
Aircraft Equipment Problem Less Severe; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Provided Assistance; Flight Crew Became Reoriented; Flight Crew FLC Overrode Automation; Flight Crew Requested ATC Assistance / Clarification; Flight Crew FLC complied w / Automation / Advisory
Aircraft
On departure flying the POM1 in FMS mode; of Runway 26L on 258 heading;  just prior to intercepting a 294 course inbound to POM our we received MSG on our PFD and FMS Position uncertain. Noticed something didn't look right; I switched over to green needles and flew the 294 radial off of the PDZ VO which by this time had been over flown by approx. 1 dot; I corrected picked up the radial and continued the climb to 7000 crossed POM flew the POM 294 to BUCCK and climbed to 14;000 [feet] for BUCCK which was our clearance limit alt. Nothing was ever mentioned by [ATC] about our course and we let them know we had lost our GPS and we're flying VOR to  VOR and would need new routing to reflect such. Within 5 not longer than 10 mins our GPS came back both agreed on position and RNP 1.0 we continued without further incident.
CE-560XLS Captain reported GPS position warning / failure during climb out.