B777 captain reported GPS navigation issues departing llbg that could have been related to military ...

Attributes
ACN	1526316
Time
Date	201803
Local Time Of Day	0001-0600
Place
Locale Reference	LCCC.ARTCC
State Reference	FO
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Make Model Name	B777 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Climb
Flight Plan	IFR
Component
Aircraft Component	GPS & Other Satellite Navigation
Person 1
Function	Captain Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 270 Flight Crew Total 12339 Flight Crew Type 6742
Events
Anomaly	Aircraft Equipment Problem Less Severe

Narrative:

Passing FL260 on climb out from llbg; got 'ads B out right' EICAS message. Performed checklist and received 'ads B out left' message. 5 minutes later at FL300 in cruise received 'unable rnp'; 'runway system'; 'terr position'; 'GPS' additional messages. Rnp showed 2.75 miles right of course. Contacted nicosia center to verify position and used rds VOR for navigation. Contacted dispatch and maintenance. Maintenance showed multiple aircraft navigation failures downloaded. He suggested we may fly out of area of disturbance; something similar had happened in same area recently. Operations returned to normal when passing into greek airspace. All navigation systems returned to normal. Everyone involved seemed to believe we were being 'jammed' by possible military aircraft. Continued to destination.

Original NASA ASRS Text

Title: B777 Captain reported GPS navigation issues departing LLBG that could have been related to military jamming.

Narrative: Passing FL260 on climb out from LLBG; got 'ADS B OUT R' EICAS message. Performed checklist and received 'ADS B OUT L' message. 5 minutes later at FL300 in cruise received 'UNABLE RNP'; 'RUNWAY SYS'; 'TERR POS'; 'GPS' additional messages. RNP showed 2.75 miles right of course. Contacted Nicosia Center to verify position and used RDS VOR for navigation. Contacted Dispatch and Maintenance. Maintenance showed multiple aircraft navigation failures downloaded. He suggested we may fly out of area of disturbance; something similar had happened in same area recently. Operations returned to normal when passing into Greek airspace. All navigation systems returned to normal. Everyone involved seemed to believe we were being 'jammed' by possible military aircraft. Continued to destination.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

B777 captain reported GPS navigation issues departing llbg that could have been related to military jamming.