PA-31P Navajo P
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Flight Instructor
Flight Crew Last 90 Days 146; Flight Crew Total 18300
Situational Awareness
Aircraft Equipment Problem Less Severe; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Returned To Clearance; Flight Crew Became Reoriented; Flight Crew Overcame Equipment Problem
Aircraft; Environment - Non Weather Related
GPS system went into Dead Reckoning mode; but we did not notice right away.  After about 5 minutes; it found the aircraft position again and updated; showing the aircraft track about a mile further west than it had displayed before.  We were traveling north just outside of the ZZZ Class Bravo.  We do not believe we penetrated the edge of the airspace at any time; but once the GPS came back online and updated; we were substantially closer than we had been believed based on the previous; ambiguous; nav data.
PA-31 Single Pilot Captain reported a navigation error due to temporary loss of GPS data.