A RAF navigator gave plane-spotters a chuckle as he held up a sign reading 'I'm with stupid' with an arrow pointing to the pilot. The pair were on a training mission in a ÂŁ13million Tornado GR4 aircraft, capable of reaching 1,400mph, when the navigator pulled the prank as they jetted through a valley in Wales. Based at RAF Lossiemouth in the Scottish Highlands, the men were flying through Snowdonia, in northern Wales, at the time of the Top Gun stunt. Knowing there would be spotters in the area, the amused navigator produced the homemade sign and sure enough, it was...