Conflicts between Random Flights in a Given Area

Ratcliffe, S.; Ford, Ray

doi:10.1017/s0373463300043101

Cited by 12 publications

(21 citation statements)

References 8 publications

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“…Thus: alarm rate against subset = 4(p-i)Z t sm c J(s) ds/AH cos<j). By integration, the alarm rate against the whole opposing population of p -1 aircraft is obtained as: 4 (p-i)Z t AH p J By considering each aircraft in turn to be own aircraft, a process which results in each aircraft being counted twice, the average alarm rate N for the whole population interacting with each other is found to be:…”

Section: P-i)j(s)ds/ahmentioning

confidence: 99%

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The Protected Volume of Airspace Generated by an Airborne Collision Avoidance System

Ford

1986

J. Navigation

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The shape, size and orientation of the protected volume of airspace generated by the airborne collision avoidance system currently known as TCAS II are derived. While based on constant-velocity aircraft flight paths the results are shown to have more general application. It is also shown how the essential features of the protected volume may be used to calculate alarm rates for some simple traffic patterns.

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Section: P-i)j(s)ds/ahmentioning

confidence: 99%

“…Thus the alarm would be given if the range fell below some threshold value even if the tau criterion was not violated. 4. MODIFIED TAU C R I T E R I O N .…”

Section: Introductionmentioning

confidence: 99%

The Protected Volume of Airspace Generated by an Airborne Collision Avoidance System

Ford

1986

J. Navigation

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“…1 The explanation offered is simply that the concentration of aircraft into preferred levels outweighs the advantage gained in reducing the average relative velocity between aircraft. Only aircraft which are flying in the same general direction are permitted to occupy the same flight level and so the relative velocity between aircraft which can be in conflict is reduced, thereby tending to reduce conflict rate.…”

Section: Use Of Height Rules 271mentioning

confidence: 99%

“…1 To put some flesh on the bones of the problem we take our volume of airspace to have a rectangular horizontal cross-section and to be bounded in the vertical dimension by two horizontal planes at 2000 ft and 10 000 ft, respectively. This enables us to use the results of an analysis of conflict rates and probabilities presented by Ratcliffe and Ford.…”

Section: Use Of Height Rules 271mentioning

confidence: 99%

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On the Use of Height Rules in Off-route Airspace

Ford

1983

J. Navigation

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The standard height rules applied in off-route airspace are examined to assess the degree of intrinsic safety they provide, i.e. the reduction of conflicts without action being taken by pilots or ATC. The yardstick used is the conflict rate which would obtain if the aircraft were uniformly randomly distributed in the height dimension and flying straight and level on uniformly randomly distributed tracks. It is shown that the application of the standard rules can lead to a reduction in intrinsic safety unless significant height-keeping errors are present. An alternative height rule apparently having more desirable characteristics is examined on the same basis.i. I N T R O D U C T I O N . The height rules for air traffic management with which we are concerned here express a desired relationship between the height of an aircraft and the direction of its track. Such rules are used in both controlled and uncontrolled airspace and are well entrenched in the art of air traffic control. The fact that ATC has been more of an art than a science, although this situation is rapidly changing, perhaps explains why the rationale for the rules is difficult to find in the literature and the rule books for the subject. Indeed, the function of the rules may be different for the two basic categories of airspace -controlled and uncontrolled. For controlled airspace it could be that the rules are applied to facilitate the task of the air traffic controller in keeping aircraft safely separated. Thus it is the controller who achieves safe separation, and the rule is a tool for the purpose rather than a means of imposing an initial degree of protection which is then enhanced by the controller. This'is surmise, of course, and it needs to be made quite clear that this paper is in no way an examination or criticism of the rules and procedures in operation in controlled airspace.Our interest is in off-route airspace, where the situation is quite different. In a so-called 'open' Flight Information Region any air traffic control service offered is probably an advisory one and, when operating under visual flight rules (VFR), aircraft are not required to obey the height rule applicable to the region. They are, however, recommended to obey it, and this is important because of the implication that it will be safer to do so. This does not necessarily mean that the rules are thought to reduce the frequency of close encounters; it could be that it is considered that they enable pilots to operate the 'see-and-avoid' principle more effectively.A discussion of the absolute safety of flight in uncontrolled airspace 269

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Three-dimensional conflict count models for unstructured and layered airspace designs

Sunil

Ellerbroek

Maas

2018

Transportation Research Part C: Emerging Technologies

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This paper presents analytical models that describe the safety of unstructured and layered en route airspace designs. Here, 'unstructured airspace' refers to airspace designs that offer operators complete freedom in path planning, whereas 'layered airspace' refers to airspace concepts that utilize heading-altitude rules to vertically separate cruising aircraft based on their travel directions. With a focus on the intrinsic safety provided by an airspace design, the models compute instantaneous conflict counts as a function of traffic demand and airspace design parameters, such as traffic separation requirements and the permitted heading range per flight level. While previous studies have focused primarily on conflicts between cruising aircraft, the models presented here also take into account conflicts involving climbing and descending traffic. Fast-time simulation experiments used to validate the modeling approach indicate that the models estimate instantaneous conflict counts with high accuracy for both airspace designs. The simulation results also show that climbing and descending traffic caused the majority of conflicts for layered airspaces with a narrow heading range per flight level, highlighting the importance of including all aircraft flight phases for a comprehensive safety analysis. Because such trends could be accurately predicted by the three-dimensional models derived here, these analytical models can be used as tools for airspace design applications as they provide a detailed understanding of the relationships between the parameters that influence the safety of unstructured and layered airspace designs.

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Conflicts between Random Flights in a Given Area

Cited by 12 publications

References 8 publications

The Protected Volume of Airspace Generated by an Airborne Collision Avoidance System

The Protected Volume of Airspace Generated by an Airborne Collision Avoidance System

On the Use of Height Rules in Off-route Airspace

Three-dimensional conflict count models for unstructured and layered airspace designs

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