An important aspect of GPS spoofing and jamming is being missed in the media...

Описание: Talking to pilots and operators, an important aspect of GPS spoofing and jamming is being missed from the narrative in the media...

We know about position spoofing, that's a given. What doesn't appear to be getting much attention is the effect of time spoofing.
 
GPS clocks have protection against time being rolled backwards but not forwards. 
 
An incident occurred where time was spoofed a significant period into the future. This meant that some of the digital certificates on board an aircraft became invalid and caused electronic communications to fail.
 
There are examples of aircraft being grounded for several weeks for systems to be reflashed and the clocks to be reset. Coarse time spoofing could therefore ground entire fleets.

Fortunately, effects vary between aircraft and are increasingly being mitigated. Later models appear to be less affected, and a solution in hybrid GPS is already close.