Tall-masted ship approaches a dock or recedes from it. High altitude aircraft. GPS and other satellites. Apollo on the moon. Failure of Mercator projection maps to find shortest distance between two points. The Earth is curved.

Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz3.pdf