Five years of aerial surveys undertaken from 1993 through 2003 showed a steep decline in sighting rates.

Various species of whales and dolphins can be seen around Tristan from time to time with increasing sighting rate.

Where is the acceleration perpendicular to instantaneous line of sight , is the proportionality constant generally having an integer value 3-5 (dimensionless), is the line of sight rate, and V is the closing velocity.

This allows the pilot to fly against a machine with known performance values and allows aircrew to build their awareness of important concepts such as sight picture, rates of closure and line of sight rates that are cues to being successful in the visual arena.