It's been a while since I was on a Sqn Exchange with Sweden, but then they were authorised to not below 20 metres overland and 10 metres oversea, unless they were a recce sqn when it was 10 metres everywhere. Weird cockpit as I remember in the Viggen. Height in metres with zero at the bottom of the dial, on the basis that you climb away from the ground underneath you. speed in kilometres per hour and from the back seat you had 2 periscopes so that you could see forward down each side, but with your head in the normal position you couldn't look down both at once. I remember that 1,000 kph at 10 metres while wearing enough survival gear to last a week in the frozen wastes had me looking like a jibbering wreck! Very impressive Air Force and extremely capable, despite relatively low flying rate.