29 Aralık 2007 Cumartesi



by Ali R+ SARAL

ABSTRACT : A method to predict the number of air-misses in a certain time duration and region based on performance, reliability, complexity and weather factors of an Air Traffic Control system.
KEYWORDS : ATC, air traffic control, vertigo, metrics, airmiss

Barbaros Mah. Sedef Sok. Onur Sit. 13/13

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It is fatally important to ponder on the issues of Air Traffic Control (ATC) where the development pace of the available technologies may have overcome the development of the systems available and the belief in the unity of support to the people in the air is incidentally hurt in the wake of the recent air traffic accidents. I believe it is critically important to have the scientific communities' support and wide contribution in order to overcome the challenges that are coming ahead, the difficulties in the cooperation of Short Term Conflict Alert displays this alone.

This article proposes a prediction method to find the number of air misses in a given duration of time in a certain region. If it is applied concurrently and coherently it may point at where the first accident lying ahead is likely to happen. It depends on the fair and precise measurement of the controllers', ATC centers', airlines', technical support and systems' performance factors and the weather factors. The details of these metric values may be the subject of another article.

Air traffic control (ATC) system is a dynamic system. ATC system's behaviour changes through time according to the changes in the input and system parameters. In fact, 'the evolution of ATC system in time depends on the complex interactions of the timing of various discrete events' (1), such as the entry of many aircrafts in a certain period of time into a certain control region and the exit flowing rate of these aircrafts and how the ATC system reacts to this traffic both psychologically on the control team basis and the availability of the technical infra-structure of the system as a whole.

A mathematical model of an ATC system is given in equation [1]. This equation provides a metrical method, which may help to overcome the 'vertigo effect' of ATC, namely 'the false sense of safety'. Similar to any metrical value this equation may help to indicate the direction if not the value of the change of safety in the air provided that it is applied with vigorous consistency.
amiss = [ 1 - K * p * r * (1 - e * w ] * trd * dur (1)

amiss # of air misses for dur
trd average # of flights per day for the controlled duration and region [real num / day ]
dur total flight duration
p performance factor
r reliability factor
c complexity factor
w weather factor

K is a constant determined by the complex interaction of p, r, c, w. It reflects the composite effect of these factors. K can be determined and improved by using legal recording and other data.

a is a constant that determines the sensitivity of the traffic problem domain to the complexity of the ATC system. It may be determined heuristically in the beginning.

p,r,c,w are assumed constant for dur

0 < p =" 0," p =" 1," r =" 0," r =" 1," c =" 0," c =" 1," w =" 0," w =" 1" s =" amiss" safety =" number" s =" [" f =" amiss" size="1">NOTES
1- p(t) indicates performance factor which is calculated from the daily measurement of the control center, airlines and the airport performances.
2 - r(t) indicates the reliability of the ATC center availability or some of its facilities, the reliability of the airlines and the airports.
3 - c(t) indicates operational complexity such as route complexity, operational complexity and the technical system soft-hardware and support-development complexity.
4- w(t) indicates the risk affect of repeated or random weather difficulties in the controlled region.

(1) Yu-chi Ho, "Performance Evaluation and Perturbation Analysis of Discrete Event Dynamic Systems", Transaction on Automatic Control, Vol. AC-32, No.7, July 1987
(2) Paul M. Frank, "Introduction to System Sensitivity Theory", Academic Press, New York, ISBN 0-12-265650-4
(3) Deutsche Flug Sicherung Presseinformation, Offenbach, 2 July 1996
(4) Rules for the Air and Air Traffic Services (Doc 4444 inter alia)
(5) The Karlsruhe Operating Data System EUROCONTROL

Ali R+ SARAL holds a M.Sc. (1985) degree in Electronics and Telecommunication Engineering from Istanbul Technical University, Istanbul, TURKEY and a second M.M. degree (1992)in Music Theory and Composition from Illinois State University, Normal, Illinois, USA. He has worked as a systems programmer in major banks and holdings in Istanbul and has served 5 years to the European Organisation for the Safety of Air Navigation (EUROCONTROL) as a senior analyst programmer. The Operational Deficiencies he has fixed in concurrence with his colleaques' other works have contributed to the safety of people in Germany inter alia. Currently, he teaches at Yeditepe University, Istanbul.