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 on June 24. The pair were on a training mission in a £13million 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 stunt.