Navigation paradox

The navigation paradox states that increased navigational precision may result in increased collision risk. In the case of ships and aircraft, the advent of Global Positioning System (GPS) navigation has enabled craft to follow navigational paths with such greater precision (often of the order of plus or minus 2 m), that, without better distribution of routes, coordination between neighboring craft and collision avoidance procedures, the likelihood of two craft occupying the same space on the shortest distance line between two navigational points has increased.

Robert E. Machol, an American engineer who worked with the FAA, attributes the term "navigation paradox" to Peter G. Reich, writing in 1964, and 1966, who recognized that "in some cases, increases in navigational precision increase collision risk". He further notes "that if vertical station-keeping is sloppy, then if longitudinal and lateral separation are lost, the planes will probably pass above and below each other. This is the ‘navigation paradox’ mentioned earlier."

Russ Paielli wrote a mid-air collision simulating computer model 500 mi² (1,300 km²) centered on Denver, Colorado. Paielli notes that aircraft cruising at random altitudes have five times fewer collisions than those obeying discrete cruising altitude rules, such as the internationally required hemispherical cruising altitude rules. At the same vertical error, the prototype linear cruising altitude rule tested produced 33.8 fewer mid-air collisions than the hemispherical cruising altitude rules.