Cessna Citation Undifferentiated or Other Model
Flight Crew Instrument; Flight Crew Flight Instructor; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Flight Crew Last 90 Days 50; Flight Crew Total 6110; Flight Crew Type 850
Human-Machine Interface; Confusion; Situational Awareness; Workload; Troubleshooting
Aircraft Equipment Problem Less Severe; Inflight Event / Encounter Other / Unknown
Aircraft Equipment Problem Dissipated; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Became Reoriented
Environment - Non Weather Related
While cruising at 17;000 feet in IMC along V139 over Warning Area W-107B near MANTA intersection; the FMS message indicator came on and the FMS reported 'position uncertain' and 'dead reckoning mode'. A check of the navigation sensors showed no GNSS (GPS) position. The FMS then requested that certain VORs be manually tuned on NAV1. The crew reported the loss of RNAV capability to New York ARTCC. The crew switched to conventional (VOR) navigation and continued the flight to the destination.
The reporter believed the loss of GPS was jamming of some sort and the aircraft was over W-107B where Naval operations may have been in progress. ATC was not aware of a planned GPS outage; nor was a NOTAM issued. Their aircraft's GPS displayed no satellites available but returned to normal functioning on its own a short time later.
A Cessna Citation Captain reported a loss of GPS signal and satellite coverage along V139 over W-107B at 17;000 feet. GPS function returned a short time later.