Air carrier pilot reported GPS jamming in Jeddah FIR airspace. The location was in the vicinity of Red Sea/Sinai Peninsula.

Narrative

During cruise flight near departing the Jeddah FIR; vicinity of Red Sea/Sinai Peninsula we began to receive indications of GPS jamming. I have received several operation group emails indicating jamming and spoofing in the Cairo FIR that have been significant and was alert for that potential. I was not expecting to see in Jeddahs airspace. On L550 approximately 10nm east of OBNAK we received a TRANSPONDER R EICAS approximately 50nm east of KITOT we got a TRANSPONDER L EICAS followed shortly after by TERR POS EICAS. The ND (Navigation Display) indicated that the GPS was gone and the aircraft was navigating on IRS (Inertial Reference System) (3) and shortly after with IRS-DME/DME. The GPS data on the FMC POS pages was gone. I informed Jeddah Control that we were negative GPS. With DME updating and sufficient ground nav aids available for position cross checks I did not have a concern regarding position reliability. Some operators appear to have had much more significant navigation failure outcomes. The period of GPS loss was approximately 250nm and systems began to normalize in the vicinity of SISIK on N697. The rest of the flight through Cairo was uneventful.