Tornado radar ...
Why have I just remembered being told that the "ground hugging radar" fitted to Tornadoes in the 80s/90s (and one of the reasons the US was so keen to have the UK on board for Gulf War I, as they didn't have that capability) was actually a lump of concrete, and any "gee-whizz" low flying was actually down to the pilot ?
Biting the hand that feeds IT
