Re: Obviously not GPS jamming
I do hope and expect the pilots compare output from different systems, as well as to their dead reckoning.
My dad told stories about that (he was master of a small cargo ship), going from UK to Iceland sometime in the 60es. Radar was broken, strong westerly winds, snow showers, and all they had of navigational info was the direction of a radio beacon in Norway. As they ship was empty, they knew they drifted sideways, so where exactly were they on the line? Then the snow cleared, and 8 miles ahead was Iceland! He used to say "a lot of things go well"