Challenger 300
Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Flight Crew Last 90 Days 100; Flight Crew Total 21000; Flight Crew Type 150
Situational Awareness
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Overcame Equipment Problem
Aircraft; Equipment / Tooling
When aircraft was powered up; we noted a message on the Flight Management System (FMS) CDU's stating 'GNSS [Global Navigation Satellite System] NOT AVAILABLE'. We checked the status page for faults; and noted that neither GPS was acquiring satellite signals. We initially attributed it to the fact that we were surrounded by metal buildings; and that the GNSS system would eventually acquire the constellation. In addition to GNSS navigation; our aircraft is configured with an IRU with DME/DME updating to the FMS. As such we met all required navigation performance for our flight(s).After leg 1; we discovered that there was a nationwide anomaly with GNSS systems of a particular make and model; which affected many aircraft; other than ours. We operate using the Bombardier Master Minimum Equipment List (MMEL). The MMEL states that one GNSS system must be operable for dispatch. However; as the anomaly was not based within our on board system; we agreed that the continued operation was allowable. During our last leg; we received a message from our company that this anomaly did indeed fall under the control of the MMEL; and as such all company aircraft with the affected GNSS system were not suitable for flight.As stated above; with IRU-DME/DME updating to the FMS; we met all RNP requirements for the operations conduction. As such; there was no degradation of safety during any portion of our day's flights.
Reporter said this was not an aircraft problem; but a nationwide problem.  GPS manufactured by Rockwell Collins; did not get an update from the system and this sent the aircraft's system into an endless loop. A time adjustment had been made to a satellite and Rockwell Collins did not get the update into the system.
Challenger 300 First Officer reported navigational problems relating to FMS and GPS issues.