Navigation paradox
Encyclopedia
The Navigation paradox states that increased navigation
al precision may result in increased collision
risk. In the case of ship
s and aircraft
, the advent of Global Positioning System
(GPS) navigation has enabled craft to follow navigational paths with such greater precision (often on the order of plus or minus 2 meters
), 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.
attributes the term "navigation paradox" to Peter G. Reich, writing in 1964, and 1966, who recognized that "in some cases (see below) increases in navigational precision increase collision risk." In the "below" explanation, Machol noted "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 sq mi (1,295 km²) centered on Denver, Colorado
In Table 3 Paielli notes that aircraft cruising at random altitude
s have five times fewer collisions than those obeying with only 25 ft (7.6 m) RMS of vertical error discrete cruising altitude rule, 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.
Paielli’s 2000 model corroborated an earlier 1997 model by Patlovany showing in Figure 1 that zero altitude error by pilots
obeying the hemispherical cruising altitude rules resulted in six times more mid-air collisions than random cruising altitude non compliance. Similarly, Patlovany’s computer model test of the Altimeter
-Compass
Cruising Altitude Rule (ACCAR) with zero piloting altitude error (a linear cruising altitude rule similar to the one recommended by Paielli), resulted in about 60% of the mid-air collisions counted from random altitude non compliance, or 10 times fewer collisions than the internationally accepted hemispherical cruising altitude rules. In other words, Patlovany’s ACCAR alternative and Paielli’s linear cruising altitude rule would reduce cruising midair collisions between 10 and 33 times, compared to the currently recognized, and internationally required, hemispherical cruising altitude rules, which institutionalize the navigation paradox on a world wide basis.
The ACCAR alternative to the hemispherical cruising altitude rules, if adopted in 1997, could have eliminated the navigation paradox at all altitudes, and could have saved 342 lives in over 30 midair collisions (up to November 2006) since the Risk Analysis proof that the current regulations multiply midair collision risk in direct proportion to pilot accuracy in compliance. The Namibia
n collision in 1997, the Japan
ese near-miss in 2001, the Überlingen collision in Germany in 2002, and the Amazon collision
in 2006, are all examples where human or hardware errors doomed altitude-accurate pilots killed by the navigation paradox designed into the current cruising altitude rules. The current system as described by Paielli noted as examples that nuclear power plants and elevators are designed to be passively safe and fault tolerant. Reactivity control rods fall into the reactor to cause a shutdown on loss of electrical power, and elevator fall-arresting brakes are released by torque from support cable tension. The navigation paradox describes a midair collision safety system that by design cannot tolerate a single failure in human performance or electronic hardware.
To mitigate the described problem, many recommend, as legally allowed in very limited authorized airspace, that planes fly one or two miles offset from the center of the airway (to the right side) thus eliminating the problem only in the head-on collision scenario. The International Civil Aviation Organization's (ICAO) "Procedures for Air Navigation--Air Traffic Management Manual," authorizes lateral offset only in oceanic and remote airspace worldwide.. However, this workaround for the particular case of a head-on collision threat on a common assigned airway fails to address the navigation paradox in general, and it fails to specifically address the inherent system safety fault intolerance inadvertently designed into international air traffic safety regulations.[4] To be specific, in the cases of intersecting flight paths where either aircraft is not on an airway (for example, flying under a "direct" clearance, or a temporary diversion clearance for weather threats), or where intersecting aircraft flights are on deliberately intersecting airways, these more general threats receive no protection from flying one or two miles to the right of the center of the airway. Intersecting flight paths must still intersect somewhere. As with the midair collision over Germany, an offset to the right of an airway would have simply changed the impact point by a mile or two away from where the intersection actually did occur. Of the 342 deaths since 1997 so far encouraged by the lack of a linear cruising altitude rule (like ACCAR) improvement to the fault intolerance of the hemispherical cruising altitude rules, only the head-on collision over the Amazon could have been prevented if either pilot had been flying an offset to the right of the airway centerline. In contrast, ACCAR systematically separates conflicting traffic in all airspace at all altitudes on any heading, whether over the middle of the ocean or over high density multinational-interface continental airspace. Nothing about Reduced Vertical Separation Minima (RVSM) system design addresses the inherent vulnerability of the air traffic system to expected faults in hardware and human performance, as experienced in the Namibian, German, Amazon and Japanese accidents.[5]
Navigation
Navigation is the process of monitoring and controlling the movement of a craft or vehicle from one place to another. It is also the term of art used for the specialized knowledge used by navigators to perform navigation tasks...
al precision may result in increased collision
Collision
A collision is an isolated event which two or more moving bodies exert forces on each other for a relatively short time.Although the most common colloquial use of the word "collision" refers to accidents in which two or more objects collide, the scientific use of the word "collision" implies...
risk. In the case of ship
Ship
Since the end of the age of sail a ship has been any large buoyant marine vessel. Ships are generally distinguished from boats based on size and cargo or passenger capacity. Ships are used on lakes, seas, and rivers for a variety of activities, such as the transport of people or goods, fishing,...
s and aircraft
Aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...
, the advent of Global Positioning System
Global Positioning System
The Global Positioning System is a space-based global navigation satellite system that provides location and time information in all weather, anywhere on or near the Earth, where there is an unobstructed line of sight to four or more GPS satellites...
(GPS) navigation has enabled craft to follow navigational paths with such greater precision (often on the order of plus or minus 2 meters
Wide Area Augmentation System
The Wide Area Augmentation System is an air navigation aid developed by the Federal Aviation Administration to augment the Global Positioning System , with the goal of improving its accuracy, integrity, and availability...
), 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.
Research
Robert E. MacholRobert E. Machol
Robert Engel Machol was an American systems engineer and professor of systems at the Kellogg Graduate School of Management of Northwestern University. Machol wrote the earliest significant books directly related to systems engineering...
attributes the term "navigation paradox" to Peter G. Reich, writing in 1964, and 1966, who recognized that "in some cases (see below) increases in navigational precision increase collision risk." In the "below" explanation, Machol noted "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
Mid-air collision
A mid-air collision is an aviation accident in which two or more aircraft come into contact during flight. Owing to the relatively high velocities involved and any subsequent impact on the ground or sea, very severe damage or the total destruction of at least one of the aircraft involved usually...
simulating computer model 500 sq mi (1,295 km²) centered on Denver, Colorado
Denver, Colorado
The City and County of Denver is the capital and the most populous city of the U.S. state of Colorado. Denver is a consolidated city-county, located in the South Platte River Valley on the western edge of the High Plains just east of the Front Range of the Rocky Mountains...
In Table 3 Paielli notes that aircraft cruising at random altitude
Altitude
Altitude or height is defined based on the context in which it is used . As a general definition, altitude is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The reference datum also often varies according to the context...
s have five times fewer collisions than those obeying with only 25 ft (7.6 m) RMS of vertical error discrete cruising altitude rule, 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.
Paielli’s 2000 model corroborated an earlier 1997 model by Patlovany showing in Figure 1 that zero altitude error by pilots
Aviator
An aviator is a person who flies an aircraft. The first recorded use of the term was in 1887, as a variation of 'aviation', from the Latin avis , coined in 1863 by G. de la Landelle in Aviation Ou Navigation Aérienne...
obeying the hemispherical cruising altitude rules resulted in six times more mid-air collisions than random cruising altitude non compliance. Similarly, Patlovany’s computer model test of the Altimeter
Altimeter
An altimeter is an instrument used to measure the altitude of an object above a fixed level. The measurement of altitude is called altimetry, which is related to the term bathymetry, the measurement of depth underwater.-Pressure altimeter:...
-Compass
Compass
A compass is a navigational instrument that shows directions in a frame of reference that is stationary relative to the surface of the earth. The frame of reference defines the four cardinal directions – north, south, east, and west. Intermediate directions are also defined...
Cruising Altitude Rule (ACCAR) with zero piloting altitude error (a linear cruising altitude rule similar to the one recommended by Paielli), resulted in about 60% of the mid-air collisions counted from random altitude non compliance, or 10 times fewer collisions than the internationally accepted hemispherical cruising altitude rules. In other words, Patlovany’s ACCAR alternative and Paielli’s linear cruising altitude rule would reduce cruising midair collisions between 10 and 33 times, compared to the currently recognized, and internationally required, hemispherical cruising altitude rules, which institutionalize the navigation paradox on a world wide basis.
The ACCAR alternative to the hemispherical cruising altitude rules, if adopted in 1997, could have eliminated the navigation paradox at all altitudes, and could have saved 342 lives in over 30 midair collisions (up to November 2006) since the Risk Analysis proof that the current regulations multiply midair collision risk in direct proportion to pilot accuracy in compliance. The Namibia
Namibia
Namibia, officially the Republic of Namibia , is a country in southern Africa whose western border is the Atlantic Ocean. It shares land borders with Angola and Zambia to the north, Botswana to the east and South Africa to the south and east. It gained independence from South Africa on 21 March...
n collision in 1997, the Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
ese near-miss in 2001, the Überlingen collision in Germany in 2002, and the Amazon collision
Gol Transportes Aéreos Flight 1907
Gol Transportes Aéreos Flight 1907 was a Boeing 737-8EH, registration PR-GTD, on a scheduled passenger flight from Manaus, Brazil, to Rio de Janeiro. On 29 September 2006, just before 17:00 BRT, it collided in midair with an Embraer Legacy business jet over the Brazilian state of Mato Grosso...
in 2006, are all examples where human or hardware errors doomed altitude-accurate pilots killed by the navigation paradox designed into the current cruising altitude rules. The current system as described by Paielli noted as examples that nuclear power plants and elevators are designed to be passively safe and fault tolerant. Reactivity control rods fall into the reactor to cause a shutdown on loss of electrical power, and elevator fall-arresting brakes are released by torque from support cable tension. The navigation paradox describes a midair collision safety system that by design cannot tolerate a single failure in human performance or electronic hardware.
To mitigate the described problem, many recommend, as legally allowed in very limited authorized airspace, that planes fly one or two miles offset from the center of the airway (to the right side) thus eliminating the problem only in the head-on collision scenario. The International Civil Aviation Organization's (ICAO) "Procedures for Air Navigation--Air Traffic Management Manual," authorizes lateral offset only in oceanic and remote airspace worldwide.. However, this workaround for the particular case of a head-on collision threat on a common assigned airway fails to address the navigation paradox in general, and it fails to specifically address the inherent system safety fault intolerance inadvertently designed into international air traffic safety regulations.[4] To be specific, in the cases of intersecting flight paths where either aircraft is not on an airway (for example, flying under a "direct" clearance, or a temporary diversion clearance for weather threats), or where intersecting aircraft flights are on deliberately intersecting airways, these more general threats receive no protection from flying one or two miles to the right of the center of the airway. Intersecting flight paths must still intersect somewhere. As with the midair collision over Germany, an offset to the right of an airway would have simply changed the impact point by a mile or two away from where the intersection actually did occur. Of the 342 deaths since 1997 so far encouraged by the lack of a linear cruising altitude rule (like ACCAR) improvement to the fault intolerance of the hemispherical cruising altitude rules, only the head-on collision over the Amazon could have been prevented if either pilot had been flying an offset to the right of the airway centerline. In contrast, ACCAR systematically separates conflicting traffic in all airspace at all altitudes on any heading, whether over the middle of the ocean or over high density multinational-interface continental airspace. Nothing about Reduced Vertical Separation Minima (RVSM) system design addresses the inherent vulnerability of the air traffic system to expected faults in hardware and human performance, as experienced in the Namibian, German, Amazon and Japanese accidents.[5]
See also
- Air traffic controllerAir traffic controllerAir traffic controllers are the people who expedite and maintain a safe and orderly flow of air traffic in the global air traffic control system. The position of the air traffic controller is one that requires highly specialized skills...
- Air traffic controlAir traffic controlAir traffic control is a service provided by ground-based controllers who direct aircraft on the ground and in the air. The primary purpose of ATC systems worldwide is to separate aircraft to prevent collisions, to organize and expedite the flow of traffic, and to provide information and other...
- Gol Transportes Aéreos Flight 1907Gol Transportes Aéreos Flight 1907Gol Transportes Aéreos Flight 1907 was a Boeing 737-8EH, registration PR-GTD, on a scheduled passenger flight from Manaus, Brazil, to Rio de Janeiro. On 29 September 2006, just before 17:00 BRT, it collided in midair with an Embraer Legacy business jet over the Brazilian state of Mato Grosso...