Detailed summary from Ops.group, which is for pilots and flight planners.[1]
It's really bad. They write:
Typical indications of Spoofing
Unlike jamming, a GPS signal is present, but it has fake information. False GPS position, time,
and date information will be processed by the GPS receiver as being valid. As soon as this is
fed to other systems, failure messages will begin.
• Rapid EPU or ANP increase
• GPS position and IRS or FMS position disagree caution message
• Aircraft Clock time changes, or difference between Capt/FO clocks
• Transponder failure: EICAS/ECAM “ATC FAIL”
• Autopilot turns aircraft unexpectedly
• ADS-B Failure/Warning
• Synthetic Vision reverting to blue over brown
• Loss of enhanced display, such as display of terrain on PDI
• Wind indication on ND is illogical or has a major shift - erratic groundspeed
• GPS position symbol on ND drifts away from the FMS and the IRS symbols
• Datalink (CPDLC, ADS-C) failure warning
• GPS information on sensor page shows unusual values: altitude, etc.
• Handheld GPS (e.g. Garmin, iPad) disagrees with aircraft GPS position
• EGPWS audible warning (‘Pull Up”)
• GPS 1 and 2 dramatically different i.e. more than 100 meters, which may also give an
ECAM/EICAS GPS miscompare warning.
• Spoofing Alerting app e.g. Naviguard gives alert
• ACARS message from ground/ops advises of spoofing (based on aircraft downlink
message with unusual values)
Typical indications of Spoofing
Unlike jamming, a GPS signal is present, but it has fake information. False GPS position, time, and date information will be processed by the GPS receiver as being valid. As soon as this is fed to other systems, failure messages will begin.
• Rapid EPU or ANP increase
• GPS position and IRS or FMS position disagree caution message
• Aircraft Clock time changes, or difference between Capt/FO clocks
• Transponder failure: EICAS/ECAM “ATC FAIL”
• Autopilot turns aircraft unexpectedly
• ADS-B Failure/Warning
• Synthetic Vision reverting to blue over brown
• Loss of enhanced display, such as display of terrain on PDI
• Wind indication on ND is illogical or has a major shift - erratic groundspeed
• GPS position symbol on ND drifts away from the FMS and the IRS symbols
• Datalink (CPDLC, ADS-C) failure warning
• GPS information on sensor page shows unusual values: altitude, etc.
• Handheld GPS (e.g. Garmin, iPad) disagrees with aircraft GPS position
• EGPWS audible warning (‘Pull Up”)
• GPS 1 and 2 dramatically different i.e. more than 100 meters, which may also give an ECAM/EICAS GPS miscompare warning.
• Spoofing Alerting app e.g. Naviguard gives alert
• ACARS message from ground/ops advises of spoofing (based on aircraft downlink message with unusual values)
[1] https://ops.group/blog/crew-guidance-published-by-gps-spoofi...