Not quite right! It would work if you were at ground level- any plane above the horizon would be above you, and any plane below the horizon would be in deep doodoo (or probably Indonesian), but at 37,000', the horizon is significantly below you, and it is very hard to judge. You often see planes coming towards you that appear to be heading over you, and suddenly they seem to duck and shoot below you. It's almost impossible to judge sometimes. The only reliable way I found was to suspend the pilot clipboard like a spirit level through the hanging hole and look along the top edge at your target- that shows you better than anything else.
Last edited by Rainboe; 15th March 2007 at 18:51.