Business jet Captain reported GPS jamming and spoofing during cruise. The Captain identified the GPS interference threat in the region and the GPS was restored later in the flight.

Narrative

During a Part 91 private flight from HECA; significant GPS jamming and subsequently; GPS spoofing was encountered within both the Nicosia and Ankara FIR boundaries. The loss of GPS satellite coverage on both GPS 1 and 2 initially occurred abeam RNAV waypoint TUVLO at FL400; M.82. The time of the initial GPS jamming was approximately at XA55. Prior to departure the crew had discussed the potential threat of GPS interference enroute; the Captain had already experienced it several times in the region in the preceding month. The first indication was loss of ADS-B; followed by successive loss of VOR and VOR/DME. Nicola ATC were notified of the occurrence; but the IRS (Inertial Reference System) navigation was maintaining the FMS routing. However; on entering the Ankara FIR; the GPS jamming became GPS spoofing. The left-seat PIC (PM) PFD (Primary Flight Display) displayed a 200 nm confirmed position error. The right-seat SIC (Second in Command) (PF) PFD continued to display accurate position information. However; the lack of the ability for the IRS systems to update from the GPS led to dead-reckoning mode and predicted fuel errors. Furthermore; it also appeared that the ground or more likely; airborne military GPS jamming was also affecting ground VOR/DME stations. As a result; radar headings were requested from Ankara ATC. At approximately XB20 both PFDs showed a magenta background and a spurious EGPWS 'TERRAIN PULL UP!' audio and visual alert occurred. The EGPWS was selected off to cancel the alert. The GPS spoofing continued for 2 hours; until it was within the BAKU FIR. At night; in unfamiliar airspace and at a lower altitude; this could have been a far more serious situation.