Traffic Deviation Research Articles

Analysis of Long-Range Air Traffic Systems: Separation Standards — I

This paper was first published in Volume 19, p. 88, in 1966. Parts II and III were included in following issues of the Journal. The paper is Crown Copyright and is reproduced with the permission of H.M. Stationery Office. It is followed by comments from Stanley Ratcliffe.The main task of air traffic controllers is to plan traffic flows so that aircraft are allotted sufficient separation to absorb not only systematic differences in speed but also the imperfections of navigation and piloting, which we term flying errors. To this end, they usually work with three separation standards, to be applied in, respectively, the along-track, across-track and vertical dimensions of space. The separation standard for any one dimension is the minimum intended (i.e. planned) separation permitted in that dimension when the intended separations are less than standard in the other two. The problem is to choose standards which are safe enough, but not so large as to lead to unnecessary traffic delays and deviations.

Performance of Flexible and Rigid Pavements in Ohio

Deviations in traffic and performance prediction parameters and overall standard deviations applicable to Ohio were determined. Pavement test sites were selected to represent the statewide distribution of pavement designs in Ohio, characterized by such factors as material type, functional classification, and different climatic and soil regions. Core samples were obtained and several laboratory tests were conducted to determine the as-constructed material properties and variability of the design input parameters. Comparison of predicted and observed performances based on approximately 4 years of data indicated that the AASHTO equation does not predict the performance of flexible pavements in Ohio. The predicted and the observed performances for rigid pavement sites were essentially the same, that is, no change in the observed and the predicted pavement serviceability index (PSI); however, these observations were based on short-term performance data. The overall variance estimates for flexible and rigid pavements were not obtained due to lack in the change of performance data for most sections.

Parallel-route Systems for Supersonic Traffic

This is the third article of a series of three describing the methods developed at the Royal Aircraft Establishment for costing the effect of air traffic control deviations in long range systems. The first two discussed the general principles of costing and their application to the current and future systems for subsonic aircraft over the North Atlantic. The present paper considers systems for the S.S.T.The characteristics and mode of operation of the supersonic transport are untested, and it will operate at an altitude for which information is relatively scanty. This means that the results obtained for the cost penalties in a supersonic traffic system must be regarded as tentative. On the other hand, because we are considering traffic systems for aircraft at such an early stage of development, the situation can be analysed in a more fundamental way, with particular emphasis on the effect of the system on the aircraft design.

The Parallel-route System for North Atlantic Subsonic Jet Traffic

In the first of this series of papers, the general principles of costing the effect of air traffic control deviation were discussed. This paper discusses the application of these principles to a model route structure for North Atlantic subsonic jet traffic. It is shown how the, design of an optimum system is related to cost considerations and how the cost depends on variations in traffic intensity and on the level of separation standards in all three dimensions. The work on which the paper is based was carried out at the Royal Aircraft Establishment.

Costing Air Traffic Control Deviations

1. Introduction. An air traffic control system maintains adequate separation between aircraft by requiring some aircraft to deviate from the paths which they would otherwise follow. In the absence of such deviations it must be assumed that civil transport aircraft would choose to operate at the most economical combination of airspeed, track and altitude (within the limits set by inaccuracies of weather prediction); A.T.C. deviations therefore involve economic penalty to the operator. It is important to assess the magnitude of such penalties for two reasons:(a) To provide a yardstick by which to compare different A.T.C. systems.(b) To give a measure of how much might justifiably be spent on new systems and equipment, to enable separation standards (and hence the penalty of deviations) to be reduced without reduction in safety.