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EUROPEAN ORGANISATIONFOR THE SAFETY OF AIR NAVIGATION

EUROCONTROL EXPERIMENTAL CENTRE

RODOS TMA ANALYSIS

EEC Note No. 26/97

EEC Task FS0-1EATCHIP Task ISS.ET2

Issued December 1997

The information contained in this document is the property of the EUROCONTROL Agency and no part should bereproduced in any form without the Agency’s permission.

The views expressed herein do not necessarily reflect the official views or policy of the Agency.

EUROCONTROL

REPORT DOCUMENTATION PAGE

Reference:EEC Note No. 26/97

Security Classification:Unclassified

Originator:EEC - APT

(AirPorT Simulations)

Originator (Corporate Author) Name/Location:EUROCONTROL Experimental CentreB.P.15F - 91222 Brétigny-sur-Orge CEDEXFRANCETelephone : +33 1 69 88 75 00

Sponsor:Implementation Directorate

Directorate DEI 1

Sponsor (Contract Authority) Name/Location:EUROCONTROL AgencyRue de la Fusée, 96B -1130 BRUXELLESTelephone : +32 2 729 9011

TITLE:RODOS TMA ANALYSIS

AuthorsJ-L. JanszenV.Tangalos

M.J. Mc Morrow

Date

12/97

Pages

iii + 31

Figures

14

Tables

1

Appendix

2

References

EATCHIP TaskSpecification

ISS.ET2

EEC Task No.FS0-1

Task No. Sponsor Period07/97-12/97

Distribution Statement:(a) Controlled by: Head of APT(b) Special Limitations: None(c) Copy to NTIS: YES / NO

Descriptors (keywords):HCAA, EUROCONTROL, RODOS, DIAGORAS, RAC, RA, SIMMOD.

Abstract:

The Hellenic Civil Aviation Authority (HCAA) requested investigation by the EUROCONTROL Experimental Centre (EEC) of the operationalimpacts of both the introduction of Radar Procedures in the RODOS TMA, and of the reduction of the existing Arrival Longitudinal TimeSeparation Minima from 8 minutes to 6 minutes. Simulations were conducted using SIMMOD to examine these effects. This Note presentsthe findings of that study.

This document has been collated by mechanical means. Should there be missing pages, pleasereport to:

EUROCONTROL Experimental CentrePublications Office

B.P. 1591222 - BRETIGNY-SUR-ORGE CEDEX

France

RODOS TMA ANALYSISEUROCONTROL

III

TABLE OF CONTENTS

1. INTRODUCTION...............................................................................................................1

1.1 BACKGROUND....................................................................................................................11.2 OBJECTIVES ......................................................................................................................1

2. METHODOLOGY..............................................................................................................2

2.1 SIMMOD SIMULATOR ........................................................................................................22.1.1 Parameters Examined...............................................................................................2

2.2 DATA DESCRIPTIONS ..........................................................................................................32.2.1 Airspace and Airfield Data - Source.........................................................................32.2.2 Diagoras Airport - Layout ........................................................................................32.2.3 Arrival Operations ....................................................................................................3

2.2.3.1 Arrivals - RWY 07............................................................................................................... 32.2.3.2 Arrivals - RWY 25................................................................................................................. 3

2.2.4 Departure Operations................................................................................................32.2.4.1 Departures - RWY 07 ......................................................................................................... 32.2.4.2 Departures - RWY 25 ........................................................................................................... 3

2.2.5 Airspace Restrictions ................................................................................................42.2.6 Traffic Samples Used in the Simulation .....................................................................42.2.7 Procedural / Radar Routeings Used in the Simulation .............................................42.2.8 Holdstack Operations and Restrictions......................................................................42.2.9 Control Configurations Examined ..............................................................................42.2.10 Definition - “Long Final” .........................................................................................42.2.11 Scenario Data .........................................................................................................52.2.12 SIDS and STARS....................................................................................................6

2.2.12.1 SIDS and STARS - RWY 07 - Procedural and Radar Control........................................ 62.2.12.2 SIDS and STARS - RWY 25 - Procedural and Radar Control........................................ 6

2.2.13 Rodos TMA Control Positions - Existing Arrangement.........................................72.2.14 Rodos TMA Control Positions - Proposed Arrangement ........................................7

2.2.14.1 Radar Approach Controller (RAC)...................................................................................... 72.2.14.2 Radar Arrival Controller (RA).............................................................................................. 7

3. SIMMOD STUDY - RESULTS AND ANALYSIS ..............................................................8

3.1 CONTROLLER WORKLOAD INDICES - COMPARISON / ANALYSIS.............................................83.1.1 Controller Workload Indices - Summary ..................................................................9

3.2 TMA TRAFFIC LOADINGS - COMPARISON / ANALYSIS..........................................................103.2.1 Total Traffic Loadings..............................................................................................103.2.2 Peak Traffic Loadings .............................................................................................113.2.3 TMA Traffic Loadings - Summary..........................................................................12

3.3 AVERAGE AIRCRAFT TRAVEL TIMES IN THE TMA - COMPARISON / ANALYSIS .......................133.4 HOLDSTACK STATISTICS - COMPARISON / ANALYSIS..........................................................14

3.4.1 Total Number of Aircraft Held ..................................................................................143.4.2 Peak Number of Aircraft Held..................................................................................153.4.3 Average Time in the Holdstack................................................................................163.4.4 Holdstack Statistics - Summary.............................................................................17

3.5 AVERAGE AIRCRAFT TRAVEL AND DELAY TIMES - COMPARISON / ANALYSIS............................183.5.1 Average Air and Ground Travel Time - Arrivals .....................................................183.5.2 Average Air and Ground Travel Time - Departures ...............................................193.5.3 Average Air and Ground Delay Times - Arrivals ....................................................20


IV

3.5.4 Average Air, Ground and Queue Delay - Departures.............................................213.5.5 Average Aircraft Travel and Delay Times - Summary ............................................23

3.5.5.1 Average Aircraft Air Travel Times....................................................................................... 233.5.5.2 Average Aircraft Ground Travel Times ............................................................................... 233.5.5.3 Average Arrival Aircraft Air Delay ....................................................................................... 233.5.5.4 Average Arrival Aircraft Ground Delay ............................................................................... 233.5.5.5 Average Departure Aircraft Air Delay ................................................................................. 233.5.5.6 Average Departure Aircraft Ground and Queue Delays ..................................................... 23

4. SIMMOD STUDY - CONSOLIDATED SUMMARY .........................................................25

4.1 CONTROLLER WORKLOAD INDICES .....................................................................................254.2 TMA TRAFFIC LOADINGS ..................................................................................................254.3 HOLDSTACK STATISTICS....................................................................................................254.4 AVERAGE AIRCRAFT TRAVEL AND DELAY TIMES ...................................................................26

5. CONCLUSIONS ..............................................................................................................27

6. ANNEX A - SIMMOD - DESCRIPTION........................................................................28

6.1 HOW ARE THE END RESULTS ACHIEVED? .............................................................................286.2 INPUT REQUIREMENTS.......................................................................................................286.3 OUTPUT ..........................................................................................................................286.4 AIRFIELDS, WHICH INCLUDES: ............................................................................................286.5 SECTORS, WHICH INCLUDES: .............................................................................................296.6 POINTS, WHICH INCLUDES: ................................................................................................296.7 ROUTES, WHICH INCLUDES:...............................................................................................296.8 SIMULATION ANIMATION ....................................................................................................296.9 DISADVANTAGES - LIMITATIONS..........................................................................................29

7. ANNEX B - WORKLOAD CALCULATIONS - DESCRIPTION.....................................30


1

RODOS TMA ANALYSIS

1. Introduction

1.1 Background

The Hellenic Civil Aviation Authority (HCAA) requested that the EUROCONTROLExperimental Centre (EEC) APT Centre of Expertise at Brétigny-sur-Orge examinethe impacts of the introduction of new procedures, including the use of Radar, withinthe Thessaloniki, Kerkira, Rodos and Iraklion TMAs using fast-time simulation.

The results of the studies in respect of Thessaloniki were published under EECNotes 4/96 and 17/96, respectively. Those in respect of Kerkira were publishedunder EEC Note 15/97. This Note contains the results of the Rodos TMA study. Ananalysis of the Iraklion TMA will be conducted at a future date.

1.2 Objectives

This study is to determine the impacts, in terms of both traffic flow and controllerworkload within the RODOS TMA, of the following:

• The reduction of the Arrival Procedural Longitudinal Time Separation Minimapresently in use in the RODOS TMA from 8 Minutes to 6 Minutes, and

• The introduction of Radar Control in the Rodos TMA. Note: Very high Average Departure Aircraft Ground Delay and Average Departure

Aircraft Queue Delay values were identified when using the Arrival LongitudinalTime Separation Minima of 6 Minutes in conjunction with Arrivals blockingDepartures when on ”Long Final”. In order to assess the possible alleviation ofthese delays, additional simulations were conducted in which Departures werepermitted until an Arrival was on Final Approach at a distance of 7 NM fromTouchdown. These extra simulations, combining the reduced Arrival LongitudinalSeparation Minima of 6 Minutes and the Arrival blocking Departure distance of 7NM, are incorporated in Table 1 on Page 5 as scenarios R1F and R2Frespectively.


2

2. Methodology

In order to assess the foregoing impacts, APT compared the results obtained whenutilising existing procedures with those realised under the proposed arrangements,using SIMMOD1 simulation modelling.

2.1 SIMMOD SimulatorEUROCONTROL uses SIMMOD software in conjunction with specialised pre- andpost-processors to analyse airspace and airfield systems. SIMMOD models theaircraft movement, both in the air and on the ground, gathering statistics for eachelement. These statistics are processed to provide aircraft travel and delay times,estimates of sector workload indices, and a graphical animation of the simulation.

Additional information on SIMMOD can be found at Annex A to this Report.

2.1.1 Parameters Examined APT used SIMMOD in the course of this study to measure:

• Sector Workload Indices,

• TMA Total and Peak Traffic Loadings,

• Holdstack Statistics,

• Aircraft Travel and Delay Times, and

• Departure Queue Statistics.

1 SIMMOD is the US Federal Aviation Administration’s Airport and Airspace Model


3

2.2 Data Descriptions

2.2.1 Airspace and Airfield Data - SourceThe Hellenic Civil Aviation Authority provided Airspace and Airfield data for existingarrangements in the Rodos TMA, together with proposed modifications considerednecessary to achieve the objectives of the study.

2.2.2 Diagoras Airport - Layout

Figure 1

2.2.3 Arrival Operations

2.2.3.1 Arrivals - RWY 07

Turbo-Prop Aircraft (ATR 42, ATR 72, DO28 etc.) and Light Aircraft vacate at LinkCHARLIE.

Jet Aircraft vacate at Links CHARLIE or ALPHA

2.2.3.2 Arrivals - RWY 25

Turbo-Prop Aircraft (ATR 42, ATR 72, DO28 etc.) and Light Aircraft vacate at LinkCHARLIE.

Jet Aircraft vacate at Links DELTA or FOXTROT

2.2.4 Departure Operations

2.2.4.1 Departures - RWY 07

All aircraft depart from the Runway Threshold.

2.2.4.2 Departures - RWY 25

All aircraft depart from the Runway Threshold.


4

2.2.5 Airspace RestrictionsDiagoras Airport is surrounded by mountainous terrain, having Minimum SectorAltitudes of 5500 Feet in the sector 180º to 270º Magnetic, and 4000 Feet in thesector 270º to 180º Magnetic, within 25 NM of the PARADISI (PAR) VOR. Inaddition, the Airport is situated approximately 8 NM South of the common Athinai /Istanbul FIR Boundary. The operational constraints imposed by thesecircumstances, both in terms of terrain clearance and available manoeuveringairspace, are observed in the simulation.

2.2.6 Traffic Samples Used in the SimulationThe HCAA provided an initial traffic sample, representative of a 24 hour period atDiagoras Airport in a busy month in 1997, consisting of 182 IFR and VFRmovements. In addition, EUROCONTROL Headquarters provided forecast trafficfigures for a similar day’s traffic in the year 2000, consisting of 214 IFR and VFRmovements. Actual traffic samples for 1997 (Basecase), and forecast samples forthe year 2000 are used in the simulation.

2.2.7 Procedural / Radar Routeings Used in the SimulationAt the request of HCAA, Radar routeings used in the simulation are identical to thoseutilised for Procedural Control.

2.2.8 Holdstack Operations and RestrictionsFor the purposes of the simulation, and to enable optimum traffic management toFinal Approach, all RODOS IFR Arrivals, whether operating under Procedural orRadar Control, are required to route via the RDS VOR irrespective of the requirementto Hold. Aircraft obliged to enter the RDS Holdstack are held therein until therequired Longitudinal Separation is established. For the purposes of the simulation,the minimum periods spent in the Holdstack are four minutes when operating underProcedural Control and two minutes when operating under Radar Control.

2.2.9 Control Configurations ExaminedConfigurations using both Procedural and Radar Control are examined in the courseof this study.

2.2.10 Definition - “Long Final”For the purposes of the simulation, and as used in this Report, the term “Long Final”indicates a position considered as the point on Final Approach at which an aircraftfollowing the published TVOR/DME Approach to Runway 07, or the published ILSApproach to Runway 25, would intercept the Final Approach Track. That is to say,an aircraft is considered as being on “Long Final” when it is on Final Approach and ata distance of 10 NM from Touchdown.


5

2.2.11 Scenario Data

ExerciseID

TrafficSample

Runway-in-Use

ControlMethod

Used

LongitudinalSeparation

Minima

ControlUnit

ArrivalsBlocking

DeparturesARR DEP

R1A 1997 07 Proc 8 MIN 5 MIN TMA Long FinalR1B 2000 07 Proc 8 MIN 5 MIN TMA Long FinalR1C 2000 07 Proc 6 MIN 5 MIN TMA Long FinalR1D 2000 07 Radar 5 NM 5 MIN RAC/RA From 5 NMR1E 2000 07 Radar 5 NM 3 MIN RAC/RA From 5 NMR1F 2000 07 Proc 6 MIN 5 MIN TMA From 7 NMR2A 1997 25 Proc 8 MIN 5 MIN TMA Long FinalR2B 2000 25 Proc 8 MIN 5 MIN TMA Long FinalR2C 2000 25 Proc 6 MIN 5 MIN TMA Long FinalR2D 2000 25 Radar 5 NM 5 MIN RAC/RA From 5 NMR2E 2000 25 Radar 5 NM 3 MIN RAC/RA From 5 NMR2F 2000 25 Proc 6 MIN 5 MIN TMA From 7 NM

Table 1

Table 1 above summarises the simulation scenarios examined. The relevantoperational criteria associated with each exercise is also presented.


6

2.2.12 SIDS and STARSThe RODOS TMA is simulated using scenarios for both Runway 07 and Runway 25at Diagoras Airport. The same routeings are used under both Procedural and RadarControl. The following sub-sections illustrate the routeings modelled for both Arrivingand Departing traffic.

2.2.12.1 SIDS and STARS - RWY 07 - Procedural and Radar Control

Figure 2

2.2.12.2 SIDS and STARS - RWY 25 - Procedural and Radar Control

Figure 3


7

2.2.13 Rodos TMA Control Positions - Existing ArrangementRODOS TMA is currently controlled by a single Procedural Approach Controller whois responsible for the provision of ATC Service to both Arrivals and Departures. Forthe purposes of the simulation the Procedural Approach Control Position isdesignated as TMA.

2.2.14 Rodos TMA Control Positions - Proposed ArrangementWith the introduction of Radar Control, the Rodos TMA will be operated by two RadarControllers. For the purposes of the simulation the two Control Positions concernedare designated Radar Approach Control (RAC), and Radar Arrival (RA), respectively.The responsibilities of the Controllers operating these Control Positions are asfollows:

2.2.14.1 Radar Approach Controller (RAC)

The provision of Radar Service to Arrival, Departure and Transit traffic, from the timeControl of such traffic is accepted from the transferring ATSU until such time as it istransferred to the Radar Arrival Controller, in the case of Arrivals, or to the nextaccepting ATSU in the case of either Departures or Transit traffic.

2.2.14.2 Radar Arrival Controller (RA)

The provision of Radar Service to Arriving Traffic, from the time Control of suchtraffic is accepted from the Radar Approach Controller (RAC) until such time as it istransferred to the Aerodrome Controller for landing. The Radar Arrival Controller (RA)is particularly responsible for the Radar Vectoring of Arriving traffic to a position fromwhich a successful landing can be accomplished, or a missed approach initiated.For the purposes of the simulation, the Radar Arrival Controller (RA) also handlesVFR Arrivals while they are on Final.


8

3. SIMMOD Study - Results and AnalysisThe following subsections detail the results obtained from investigation of theparameters listed under 2.1.1 above using SIMMOD output. The results arepresented in graphical format.

3.1 Controller Workload Indices - Comparison / AnalysisThe Workload Indices are calculated using output of the SIMMOD simulation,assigning workload weightings to aircraft events obtained from the simulation. Ahigher index value corresponds to a higher level of work for that controller. Themethodology used for calculating the workload indices is described at Annex B.

Individual controller workload indices are suitable for the comparison of one scenarioto another, or separate controller working positions within a scenario. They are not,however, intended as absolute measures of controller workload. A valid comparisonmay, for example, be drawn between the workload indices of the existing TMAcontroller, and that of either the RAC controller or the RA controller provided underthe revised Radar Control arrangement. It would, however, be invalid to compare thecollective total workload indices of both RAC and RA controllers concerned withthose of the single TMA controller operating under the existing organisation.

C o n tro l le r W o rk lo a d I n d ic e s

0

5 0

1 00

1 50

2 00

2 50

3 00

3 50

4 00

4 50

R1A

R1B

R1C

R1D

R1D

R1E

R1E

R1F

R2A

R2B

R2C

R2D

R2D

R2E

R2E

R2F

S c e n a r io s

Wor

kloa

d In

dex

TMA

RA C

RA

Figure 4

Figure 4 depicts the controller workload indices obtained from the SIMMODsimulation for the Rodos TMA. The individual values depicted are specific to aparticular scenario, runway-in-use, and to the Control method used.

Figure 4 clearly demonstrates that the introduction of Radar Control procedures inthe Rodos TMA produces workload values in respect of both the RAC and RAcontrollers that are considerably lower than those experienced by the single TMAcontroller in the existing arrangement. These lower values are due, not only to thefact that the original workload is split between two controllers under the newarrangement, but also to the more efficient handling of traffic made possible by theintroduction of Radar procedures.


9

The results in respect of scenarios R1A and R2A, which show lower values than theother scenarios controlled by the TMA controller, are based upon traffic samples for1997. All other scenarios are based upon traffic samples for the year 2000.

Scenarios R1C and R2C generate slightly lower Workload values than do scenariosR1B and R2B. This is due to the effects of the reduction in Longitudinal TimeSeparation required for Arrivals from 8 Minutes to 6 Minutes, and to the consequentlessening of controller input necessary to maintain an orderly and expeditious trafficflow.

Reducing the distance at which Arrivals block Departures from that of “Long Final” asin scenarios R1C and R2C, to a figure of 7 NM from Touchdown as in scenarios R1Fand R2F, does not generate any additional lowering of Controller Workload Indexvalues.

The Controller Workload Indices produced for Runway 07 show marginally highervalues than those for Runway 25.

Workload Indices in respect of the RAC controller are considerably higher than thoseof the RA controller in all instances. This is due to the fact that the RAC controllerprovides Radar Service to all IFR Arrival, Departure and Transit traffic, while the RAcontroller handles only IFR Arrivals and those VFR aircraft on Final.

3.1.1 Controller Workload Indices - SummaryOutput of the SIMMOD simulation shows that Controller Workload Indices arereduced by the following factors:

• The reduction of the Arrival Longitudinal Time Separation Minimum from 8Minutes to 6 Minutes, and

• The introduction of Radar procedures.


10

3.2 TMA Traffic Loadings - Comparison / AnalysisThe graphs in this section are based upon SIMMOD output and illustrate the Totaland Peak traffic levels handled by the individual controllers involved, whether TMA,RAC or RA, for each of the scenarios in which they provided ATC Service.

3.2.1 Total Traffic Loadings

T M A T o ta l T ra ffic L o a d in g s

02 0

4 0

6 08 0

1 00

1 201 401 60

1 802 00

R1A

R1B

R1C

R1D

R1D

R1E

R1E

R1F

R2A

R2B

R2C

R2D

R2D

R2E

R2E

R2F

Sc e n a r io s

Airc

raft

Mov

emen

ts

TMA

RA C

RA

Figure 5

Figure 5 above depicts the Total Traffic Load handled by the TMA, RAC or RAcontroller, as appropriate, for each of the scenarios modelled.


The results in respect of those elements of scenarios R1D, R1E, R2D and R2E thatwere handled by the RAC controller indicate lower loadings than those of the TMAcontroller. This is due to the fact that VFR traffic does not come under thejurisdiction of the RAC controller. However, in scenarios where Procedural Control isused, the TMA controller is considered as providing a service to all IFR and VFRtraffic.

With respect to the RA controller, the Total Traffic Loads handled in scenarios R1D,R1E, R2D and R2E are identical. This is because they reflect the number of aircraftlanding at the airport in accordance with the traffic sample modelled for the year2000.


11

3.2.2 Peak Traffic Loadings

T M A P e a k T ra ffic L o a d in g s

0

1

2

3

4

5

6

7

8

9

R1A

R1B

R1C

R1D

R1D

R1E

R1E

R1F

R2A

R2B

R2C

R2D

R2D

R2E

R2E

R2F

S c e n a r io s

Airc

raft

Mov

emen

ts

TMA

RA C

RA

Figure 6

Figure 6 above depicts the Peak Traffic Load handled by the TMA, RAC or RAcontroller, as appropriate, for each of the scenarios modelled.

The results in respect of scenarios R1A and R2A are based upon traffic samples for1997. All other scenarios are based upon traffic samples for the year 2000.

Peak Traffic Load values obtained from the simulation show operationallyinsignificant differences with the changes in runway orientation examined.

Scenarios simulated under the RAC controller show lower Peak Traffic Loadingsthan do those examined using Procedural Control, in all instances. This is partly dueto the fact that all VFR traffic is handled by the TMA controller under the ProceduralControl arrangement, whereas the RAC controller does not handle VFR traffic. This,coupled with the more expeditious handling possible when using Radar procedures,helps to further reduce TMA Peak Traffic Loadings under scenarios R1D, R1E, R2Dand R2E.

There is a slight decrease in TMA Peak traffic loading values with introduction of the6 Minute Longitudinal Time Separation Minima in scenarios R1C and R2C.

Reduction of the distance at which Arrivals block Departures from that of “Long Final”to a figure of 7 NM from Touchdown, as in scenarios R1F and R2F, has a negativeeffect in the case of TMA Peak Traffic Loadings in that, it actually produces highervalues than those seen under scenarios R1C and R2C. This increase in Peak TrafficLoading is due to the launching of Departures while simultaneously handling a higherfrequency of Arrivals that are permitted to continue to a position on the FinalApproach that is some 3 NM closer than under any other scenario in whichProcedural Control is used.


12

3.2.3 TMA Traffic Loadings - SummaryOutput of the SIMMOD Simulation shows that TMA Total Traffic Loadings are onlyslightly reduced by the use of Radar procedures, while TMA Peak Traffic Loadingsshow a greater reduction in the same circumstances.

In the specific case of Peak Traffic Loadings, the reduction of the Arrival LongitudinalTime Separation Minima of 8 Minutes to 6 Minutes produces a slight reduction invalues.


13

3.3 Average Aircraft Travel Times in the TMA - Comparison /Analysis

Ave ra ge Aircra ft T ra ve l T im e in the TM A

0

2

4

6

8

10

12

14

R1A

R1B

R1C

R1D

R1D

R1E

R1E

R1F

R2A

R2B

R2C

R2D

R2D

R2E

R2E

R2F

Sce nar ios

Min

utes

TMA

RA C

RA

.

Figure 7

Figure 7 above depicts the Average Aircraft Travel Time in the TMA, includingperiods spent in the Holdstack, where appropriate.

The individual values depicted are specific to a particular scenario, runway-in-use,and to the Control method used.

Average Aircraft Travel Times in the TMA for those scenarios simulated underProcedural Control show higher values than those achieved using Radar Control.This is due to the higher instance of Holding necessary to achieve an optimumlanding interval under Procedural Control.

Average Aircraft Travel Times in the TMA for Runway 07 are higher than those forRunway 25 in all instances, when using Procedural Control. This results from themore complicated Approach and Departure routings to / from Runway 07 as opposedto Runway 25. While the Approach Procedure to Runway 25 is more protracted thanthat to Runway 07, the Departure routing therefrom to the North West, which is themost heavily used inbound / outbound route, is considerably shorter and lesscomplicated to follow than that from Runway 07.

When compared with the results obtained under Procedural Control the AverageAircraft Travel Times in the TMA for those scenarios simulated under Radar Controlshow lower values while operating under the RAC controller (especially in the case ofRunway 25). However, these advantages are not maintained once the aircraft istransferred to the jurisdiction of the RA controller who takes longer to vector theaircraft from the Holdstack to either Runway than does the RAC controller to vectorthe aircraft from the TMA Boundary to the Rodos Holdstack.


14

3.4 Holdstack Statistics - Comparison / AnalysisThe Holdstack statistics reported in the following sub-sections are based upon outputof the SIMMOD simulation. Each flight is examined to identify those that were held inthe Rodos Holdstack. Statistics in respect of those held are then extracted andreported in summary format.

3.4.1 Total Number of Aircraft Held

Tota l Number of Aircraft Held

0

10

20

30

40

50

60

R1A R1B R1C R1D R1E R1F R2A R2B R2C R2D R2E R2F

Scenar ios

Num

ber

of A

ircra

ft

Figure 8

Figure 8 above depicts the Total Number of Aircraft Held in the Rodos Holdstack foreach of the scenarios modelled.


The total number of aircraft held, whether using Runway 07 or Runway 25, showoperationally insignificant differences.

Scenarios R1C, R1F, R2C and R2F achieve Total Number of Aircraft Held valuesalmost equal to those of scenarios R1A and R2A, both of which were simulated using1997 traffic levels. This is due to the use of the lower Arrival Longitudinal TimeSeparation of 6 Minutes in each case.

The reduction of the distance at which Arrivals block Departures from that of “LongFinal” to a figure of 7 NM from Touchdown, as in scenarios R1F and R2F, does notgenerate any additional benefit in the Total Number of Aircraft Held value obtained.

When compared with those scenarios under Procedural Control, scenarios R1D,R1E, R2D and R2E show a very marked reduction in the number of aircraft held inthe Holdstack. This is due to the considerably more efficient handling possible whenusing Radar procedures.


15

3.4.2 Peak Number of Aircraft Held

Peak Number of Aircraft Held

00.5

11.5

22.5

33.5

44.5

5

R1A R1B R1C R1D R1E R1F R2A R2B R2C R2D R2E R2F

Scenarios

Num

ber

of A

ircra

ft

Figure 9

Figure 9 above depicts the Peak Number of Aircraft Held in the Rodos Holdstackduring each of the scenarios modelled.


The Peak Number of Aircraft identified as held during the simulation is identical forboth runway orientations.

As might be expected, the highest number of aircraft held is seen under the mostadverse circumstances applied i.e. in scenarios R1B and R2B. In these twoscenarios, year 2000 traffic, Procedural Control and the most restrictive ArrivalLongitudinal Time Separation Minima of 8 Minutes are used.

Despite the use of year 2000 traffic and Procedural Control, scenarios R1C, R1F,R2C and R2F achieve Peak Number of Aircraft Held values equal to those ofscenarios R1A and R2A, both of which were simulated using 1997 traffic levels. Thisis due to the use of the lower Arrival Longitudinal Time Separation of 6 Minutes ineach case.

In the circumstances simulated in this study the reduction of the Arrival LongitudinalTime Separation Minima from 8 Minutes to 6 Minutes shows extremely encouragingresults in terms of minimising time spent in the Holdstack.

The reduction of the distance at which Arrivals block Departures from that of “LongFinal” to a figure of 7 NM from Touchdown, as in scenarios R1F and R2F, does notgenerate any additional benefit in the Peak Number of Aircraft Held value obtained.

Scenarios R1D, R1E, R2D and R2E indicate the lowest values found in respect ofPeak Number of Aircraft held in the Holdstack. This is due to the more expeditioushandling of traffic made possible by the use of Radar.


16

3.4.3 Average Time in the Holdstack

Average Time in the Holdstack

0.00

2.00

4.00

6.00

8.00

10.00

12.00

R1A

R1B

R1C

R1D

R1E

R1F

R2A

R2B

R2C

R2D

R2E

R2F

Scenarios

Min

utes

Figure 10

Figure 10 above depicts the Average Time spent by aircraft in the Rodos Holdstackduring each of the scenarios modelled.


The Average Time aircraft are held in the Holdstack is virtually identical for bothrunway orientations.

Despite the use of year 2000 traffic and Procedural Control, scenarios R1C, R1F,R2C and R2F achieve Average Time in the Holdstack values equal to those ofscenarios R1A and R2A, both of which were simulated using 1997 traffic levels. Thisis due to the use of the lower Arrival Longitudinal Time Separation of 6 Minutes ineach case.

The reduction of the distance at which Arrivals block Departures from that of “LongFinal” to a figure of 7 NM from Touchdown, as in scenarios R1F and R2F, does notgenerate any additional benefit in lowering the time which aircraft spend in the RodosHoldstack.

Scenarios R1D,R1E,R2D and R2E indicate the lowest values found in respect ofAverage Time in the Holdstack. These values, which are particularly low in thisinstance, are due to the expeditious handling of traffic made possible by the use ofRadar.


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3.4.4 Holdstack Statistics - SummaryIrrespective of the Runway used, or whether considering the Total / Peak Number ofAircraft Held, or the Average Time in the Holdstack, the highest values are invariablyseen under Procedural Control using 8 Minutes Longitudinal Time Separation andwith Arrivals blocking Departures when on “Long Final”.

Significant benefits in terms of the Total / Peak Number of Aircraft Held and ofAverage Time in the Holdstack do accrue where Longitudinal Time SeparationMinima is reduced to 6 Minutes as in scenarios R1C and R2C. However, thereduction of the distance at which Arrivals block Departures from that of “Long Final”to a figure of 7 NM from Touchdown, as in scenarios R1F and R2F, does notgenerate any additional benefit in these circumstances.

The largest benefits in terms of reducing Total / Peak Number of Aircraft Held, orAverage Time in the Holdstack values are seen with the introduction of Radarprocedures.


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3.5 Average Aircraft Travel and Delay Times - Comparison /AnalysisThe Average Aircraft Travel and Delay Time results reported in the following sub-sections are based upon output of the SIMMOD simulation. Aircraft Travel andDelay events for each flight are recorded, extracted and averaged to providestatistics for both Arrivals and Departures. The results cover Average Aircraft Traveland Delay Times, both in the air and on the ground. For the purposes of thesimulation, Arrival Travel times are measured from a point 10 NM prior to the TMABoundary and Departure Travel Times are measured to a point 10 NM beyond theTMA Boundary.

The following results are presented:

• Average Air Travel Time - Average aircraft travel time spent in flight and duringthe Take-Off and Landing rolls.

• Average Ground Travel Time - Average aircraft travel time spent on the groundbetween the runway and the gate/parking area.

• Average Air Delay - Average aircraft delay time incurred in the airspace whileestablishing the specified Longitudinal Separation. Air Delay may be imposed byspeed restriction, re-routeing or holding.

• Average Ground Delay - Average aircraft delay on the ground in excess of theGround Travel Time, but not including delays incurred awaiting Stand availability.However, delays incurred whilst awaiting the availability of space in the DepartureQueue are considered as Ground Delay, and

• Average Departure Queue Delay - Average delay time incurred by aircraftawaiting Clearance to enter the Runway and depart.

3.5.1 Average Air and Ground Travel Time - Arrivals

Arrivals Average Air and Ground Travel Time

0

5

10

15

20

R1A

R1B

R1C

R1D

R1E

R1F

R2A

R2B

R2C

R2D

R2E

R2F

Scenarios

Min

utes Gnd Travel

Air Travel

Figure 11

Figure 11 above depicts the Average Arrival Aircraft Air and Ground Travel Times foreach of the scenarios examined in this study.


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Average Arrival Aircraft Air Travel Times are slightly longer for Arrivals on Runway25. This is because of the more protracted Instrument Approach Procedure, interms of track miles, to that runway.

Scenarios simulated under Radar Control do not indicate savings in Average ArrivalAircraft Air Travel Time when compared with those measured under ProceduralControl because, at the request of the HCAA, the Radar routeings used in thesimulation for Arrivals are identical to the published Instrument Approach Proceduresto both Runway 07 and Runway 25. In day to-day practice of course, the shorterrouteings available under Radar would undoubtedly be utilised, thereby producinglower Average Arrival Aircraft Air Travel Times.

Average Arrival Aircraft Ground Travel Times are longer for Arrivals on Runway 07.This is due to the fact that aircraft unable to clear the Runway via Taxiway CHARLIEmust continue to the end and clear via Taxiway ALPHA, thereby incurring aprotracted Taxi time penalty.

3.5.2 Average Air and Ground Travel Time - Departures

Departures Average Air and Ground Travel Time

02468

1012141618

R1A

R1B

R1C

R1D

R1E

R1F

R2A

R2B

R2C

R2D

R2E

R2F

Scenarios

Min

utes Gnd Travel

Air Travel

Figure 12

Figure 12 above depicts the Average Departure Aircraft Air and Ground Travel Timeswith respect to each of the scenarios examined in this study.


The number of aircraft in the traffic sample has no significant affect upon theAverage Departure Aircraft Air Travel Time from either Runway.

Average Departure Aircraft Air Travel Times are considerably longer for Departuresfrom Runway 07 than from Runway 25. Departures from Runway 07 are obliged toroute over the Rodos VOR before setting course to destination, while those fromRunway 25 are mostly unrestricted. The differences are made all the more


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conspicuous by the fact that the great majority of Departures are to the North West,thus enabling those from Runway 25 to set course almost immediately after take-off.

Scenarios simulated under Radar Control do not indicate savings in AverageDeparture Aircraft Air Travel Time when compared with those simulated underProcedural Control because, at the request of the HCAA, the Radar routeings usedin the simulation are identical to those used under Procedural Control. The use ofRadar for the routeing of Departures could produce significant reductions in AverageDeparture Aircraft Air Travel Times, particularly in the case of Runway 07.

Average Departure Aircraft Ground Travel Times are longer for Departures fromRunway 07 because the physical Taxi distance to the Threshold Runway 07 isgreater than that to Runway 25.

3.5.3 Average Air and Ground Delay Times - Arrivals

Arrivals Average Air and Ground Delay Time

0

1

2

3

4

5

6

R1A

R1B

R1C

R1D

R1E

R1F

R2A

R2B

R2C

R2D

R2E

R2F

Scenarios

Min

utes Gnd Delay

Air Delay

Figure 13

Figure 13 above depicts the Average Arrival Aircraft Air and Ground Delay values foreach of the scenarios examined in this study.


The greatest Average Arrival Aircraft Air Delays are seen under the most adversecircumstances modelled i.e. in scenarios R1B and R2B. In these two scenarios, year2000 traffic, Procedural Control and the most restrictive Arrival Longitudinal TimeSeparation Minima of 8 Minutes are used.

Despite the use of year 2000 traffic and Procedural Control, scenarios R1C, R1F,R2C and R2F achieve Average Arrival Aircraft Air Delay values that are onlymarginally higher than those of scenarios R1A and R2A, both of which weresimulated using 1997 traffic levels. This is due to the use of the lower ArrivalLongitudinal Time Separation of 6 Minutes in each case.


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The reduction of the distance at which Arrivals block Departures from that of “LongFinal” to a figure of 7 NM from Touchdown, as in scenarios R1F and R2F, does notprovide any operationally significant additional benefit in this instance.

Scenarios R1D,R1E,R2D and R2E indicate the lowest values found in respect ofAverage Arrival Aircraft Air Delays. This is due to the more expeditious handling oftraffic made possible by the use of Radar.

The only instance of Average Arrival Aircraft Ground Delay is seen in scenario R2C,where the value found is less than half a minute and is therefore considered as beingoperationally insignificant.

3.5.4 Average Air, Ground and Queue Delay - Departures

Departures Average Air, Ground and Queue Delay

0

10

20

30

40

50

R1A

R1B

R1C

R1D

R1E

R1F

R2A

R2B

R2C

R2D

R2E

R2F

Scenarios

Min

utes

Que Delay

Gnd Delay

Air Delay

Figure 14

Figure 14 above depicts the Average Departure Aircraft Air, Ground and QueueDelay values for each of the scenarios examined in this study.


No Average Departure Aircraft Air Delay values are identified in respect of any of thescenarios examined in this section of the study.

Both Average Ground Delays and Average Queue Delays are identified in allscenarios examined.


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In scenarios R1A and R2A Average Ground Delays of less than one minute andAverage Queue Delays of approximately three minutes are seen. Since the trafficsamples used in these scenarios are those of 1997, it is obvious that minor delayproblems already exist and remedial procedures are required if escalation with time(and consequent higher traffic levels) is to be avoided.

Using year 2000 traffic levels in scenarios R1B and R2B, and with the attendant 8Minute Arrival Longitudinal Time Separation Minima applied, Average GroundDelays of approximately 3.9 Minutes and Average Queue Delays of approximately4.5 Minutes are seen. These delays are the product of the requirement to maintain aLongitudinal Time Separation Minima of 5 Minutes between departing aircraft, withthe additional constraint that Departures are not permitted once an Arrival is on“Long Final” (i.e. on Final Approach at approximately 10 NM from Touchdown).

In scenarios R1C and R2C, with use of the reduced Arrival Longitudinal TimeSeparation of 6 Minutes, a dramatic increase in both Average Ground Delay andAverage Queue Delay of approximately 34.2 Minutes and 6.5 Minutes respectively,are seen. This is due to the reasons explained under scenarios R1B and R2Babove, with the added constraint that the reduced Arrival Longitudinal Separation inuse results in a higher frequency of Arrivals, thereby permitting less opportunity toinject Departures into the traffic stream.

Where Radar procedures are used, as in scenarios R1D and R2D, Average GroundDelay and Average Queue Delay figures of 2.6 and 3.5 Minutes respectively, ensue.Although a Departure Longitudinal Time Separation Minima of 5 Minutes is stillapplicable, the accuracy of positional information provided by Radar permits thelaunch of Departures until arriving aircraft are at a distance of 5 NM fromTouchdown, thereby reducing both Average Ground and Average Queue Delays.

In scenarios R1E and R2E the Departure Longitudinal Time Separation is reducedfrom 5 Minutes to 3 Minutes, with consequent positive effects upon both AverageGround Delay and Average Queue Delay. Figures of 1.4 Minutes and 2.0 Minutesrespectively, are recorded.

Scenarios R1F and R2F were added to the simulation programme to assess theintegrity of remedial procedures designed to address the extremely high AverageGround Delay and Average Queue Delay values determined in respect of scenariosR1C and R2C. The extra element incorporated in scenarios R1F and R2F wherebyArrivals do not block Departures until 7 NM from Touchdown presents additionalopportunities to launch Departures, thereby reducing both Average Ground Delayand Average Queue Delay to figures of approximately 1.6 Minutes and 3.3 Minutesrespectively.


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3.5.5 Average Aircraft Travel and Delay Times - Summary

3.5.5.1 Average Aircraft Air Travel Times

For reasons already explained in this Report, Average Aircraft Air Travel Times areshorter for Arrivals to Runway 07 than to Runway 25, but are longer for Departuresfrom Runway 07 than from Runway 25.

Because the Radar and Procedural routeings used in the simulation are coincident,at the request of the HCAA, the scenarios utilising Radar procedures do not indicatelower Average Aircraft Air Travel Times.

3.5.5.2 Average Aircraft Ground Travel Times

Average Aircraft Ground Travel Times are longer to / from Runway 07 than they areto / from Runway 25. In the case of Arrivals this is because those aircraft that cannotclear the runway at Taxiway CHARLIE must continue to the end and clear viaTaxiway ALPHA. In the case of Departures the physical distance from the ParkingApron to the Threshold Runway 07 is longer than that to the Threshold Runway 25.

3.5.5.3 Average Arrival Aircraft Air Delay

Irrespective of the Runway used, the highest Average Arrival Aircraft Air Delayvalues are seen under Procedural Control using 8 Minutes Longitudinal TimeSeparation and with Arrivals blocking Departures when on “Long Final”.

Conversely, and in the particular case of Average Arrival Aircraft Air Delay, largebenefits are seen where Longitudinal Time Separation Minima is reduced to 6Minutes as in scenarios R1C and R2C, although when this is combined with asituation where the distance from Touchdown at which Arrivals block Departures isset at a figure of 7 NM from Touchdown as in scenarios R1F and R2F, rather than at“Long Final”, no tangible additional benefits are seen.

The most significant reductions in Average Arrival Aircraft Air Delay are seen with theuse of Radar procedures as in scenarios R1D, R1E, R2D and R2E.

3.5.5.4 Average Arrival Aircraft Ground Delay

The only instance of Average Arrival Aircraft Ground Delay is seen in scenario R2C,where the value found is less than half a minute and is therefore considered as beingoperationally insignificant.

3.5.5.5 Average Departure Aircraft Air Delay

No Average Departure Aircraft Air Delay values are identified in respect of any of thescenarios examined in this section of the study.

3.5.5.6 Average Departure Aircraft Ground and Queue Delays

Both Average Departure Aircraft Ground and Queue Delays are identified inscenarios R1A and R2A. As these scenarios are based upon 1997 traffic levels, it isobvious that such delays already exist, albeit to a minor degree.

With the use of year 2000 traffic levels, together with the other restrictive aspectsassociated with scenarios R1B and R2B, a further minor escalation in both Average


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Departure Aircraft Ground and Queue Delays of approximately 3.9 Minutes and 4.5Minutes respectively, are noted.

With the reduction of the Arrival Longitudinal Time Separation Minima to 6 Minutesand the retention of the Departure Longitudinal Time Separation Minima of 5 Minutesin scenarios R1C and R2C, the facility to launch Departures is seriously curtailed. Inconsequence, Average Departure Aircraft Ground and Queue Delays ofapproximately 34.2 and 6.5 Minutes respectively, are identified. Serious Apron andTaxiway congestion ensues. However, where scenario R1C and R2C proceduresare combined with the Arrivals blocking Departures at a distance of 7 NM fromTouchdown arrangement, as in scenarios R1F and R2F, much lower AverageDeparture Aircraft Ground and Queue Delays of approximately 1.6 and 3.3 Minutesare achieved.

Where Radar procedures are used, as in scenarios R1D and R2D, AverageDeparture Aircraft Ground and Queue Delay values are reduced to approximately 2.6and 3.5 Minutes, respectively. Further reductions to approximately 1.4 Minutes and2.0 Minutes, respectively, are achieved by virtue of the lower Departure LongitudinalTime Separation Minima of 3 Minutes permitted under scenarios R1E and R2E.


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4. SIMMOD STUDY - Consolidated Summary

In order to assess the effects of both the reduction of Procedural Longitudinal TimeSeparation from 8 Minutes to 6 Minutes, and the introduction of Radar procedures inthe Rodos TMA, the SIMMOD Airport and Airspace Simulation Model was used tocompare Sector Workload Indices, TMA Total and Peak Traffic Loadings, HoldstackStatistics, Aircraft Travel and Delay Times and Departure Queue Statistics for theexisting arrangement with those for the proposed organisation. The specifics ofthese simulations are described under Section 2 of this Report.

The results of the studies conducted, as recorded in Section 3 above, are consideredhereunder.

4.1 Controller Workload IndicesController Workload Indices are reduced, in order of increasing benefit, by thefollowing:

• The reduction of the Arrival Longitudinal Time Separation Minima from 8 Minutesto 6 Minutes, and

• The provision of Radar and the introduction of Radar procedures.

4.2 TMA Traffic LoadingsTMA Total Traffic Loadings are reduced, by the following:

• The provision of Radar and the introduction of Radar procedures. However, thereduction achieved is slight.

TMA Peak Traffic Loadings are reduced , in order of increasing benefit, by thefollowing:

• The reduction of the Arrival Longitudinal Time Separation Minima of 8 Minutes to6 Minutes. However, the reduction achieved is slight, and


4.3 Holdstack StatisticsWhether considering the Total or Peak Number of Aircraft Held, or the Average Timein the Holdstack, reductions are achieved, in order of increasing benefit, by thefollowing procedures:




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4.4 Average Aircraft Travel and Delay TimesReductions in Average Arrival Air Delay are achieved, in order of increasing benefit,by the following procedures:



Average Arrival Aircraft Ground Delays measured in this study were considered asbeing operationally insignificant.

No Departure Aircraft Air Delays were identified in this study.

Average Departure Aircraft Ground and Queue Delays are reduced, in order ofincreasing benefit, by the following procedures:

• The provision of Radar and the introduction of Radar procedures, and

• The reduction of the Arrival Longitudinal Time Separation Minima from 8 Minutesto 6 Minutes, in combination with the procedure whereby Arrivals blockDepartures when at 7 NM from Touchdown, as in scenarios R1F and R2F.


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5. ConclusionsThe results obtained from every relevant scenario modelled in this study clearlydemonstrate the benefits to be gained by the introduction of Radar procedures in theRodos TMA. Since these benefits are demonstrated whilst restricted to the use ofrouteings designed for Procedural Control, much greater efficiencies can beanticipated where dedicated procedures / routeings are established. This isespecially so in consideration of the existing constraints imposed by bothmountainous terrain and the proximity of the Athinai / Istanbul FIR Boundary.

Because of the very high Average Departure Aircraft Ground and Queue Delayvalues noted during the simulation when modelling scenarios based on the reducedArrival Longitudinal Time Separation Minima of 6 Minutes, extra studies wereconducted to investigate their possible alleviation. These extra studies, whichappear as scenarios R1F and R2F in this Report, involve Arrivals being permitted tocontinue on Final to a position 7 NM from Touchdown before Departures aresuspended. This procedure, when combined with the reduced Arrival LongitudinalTime Separation Minima of 6 Minutes, produces very promising results in terms ofmaintaining low Average Departure Aircraft Ground and Queue Delay values. In theabsence of Radar procedures it merits operational evaluation at an early date tovalidate its efficacy in the field, especially since, on the basis of the 1997 traffic levelsexamined, some minor Departure Aircraft Ground and Queue Delays are alreadybeing experienced at Diagoras Airport.

The reduction of the Arrival Longitudinal Time Separation Minima from 8 Minutes to 6Minutes, used independently, achieves gains in several of the scenarios examined.However, in the case of Average Departure Aircraft Ground and Queue Delays itproduces unacceptably high delay values of some 34.2 and 6.5 Minutes,respectively. The procedure is therefore not recommended for use in isolation, but asexplained in the preceding paragraph, it can produce promising results whencombined with the reduced Departure / Arrival blocking figure of 7 NM fromTouchdown, when Average Departure Aircraft Ground and Queue Delays ofacceptable proportions can be anticipated.

Although not modelled in this study, a reduction in the existing DepartureLongitudinal Time Separation Minima of 5 Minutes is also seen as a means of furtherreducing Average Departure Aircraft Ground and Queue Delays.


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6. ANNEX A - SIMMOD - Description

6.1 How are the end results achieved?The complete air and ground system is represented by a network of points andconnecting segments along which the aircraft 'navigate'. Along with other point qualities,an altitude is associated to each point. This altitude is usually derived from free profilesbut can be modified to represent, for example, height restrictions, SIDs, STARs, etc.

The simulation module is the core of the SIMMOD system. The module traces the"steps" through time and space of each aircraft defined in the traffic sample from onepoint to the next along its route. Potential violations of any of the modelled separationrequirements between two or more aircraft moving towards a given point are detectedand then resolved by adjusting their arrival times at the point. Depending on theimportance of this adjustment, the controller action deemed to be causing it isinterpreted as either track adjustment, speed control, holding or re-routeing of aircraft.Such specific occurrences as overtaking in the air, shuffling aircraft in the departurequeue, as well as many other ATC procedures and actions either on the aerodrome, inthe approach/departure environment or in en-route airspace can be simulated by carefulselection of the input parameters.

6.2 Input requirementsThe SIMMOD input is constructed in a number of files. The validity and correctness ofthe input data is crucial for the accuracy and realism of the simulation. The SIMMODfiles constructed will contain detailed information regarding:

• • Geographical boundaries of airspace and restrictions,

• • Geographical boundaries of sectors and restrictions (capacities),

• • Points data and restrictions (separation standards),

• • Route data and restrictions (separation standards),

• • Airfield data and restrictions (aircraft size limitations),

• • Aircraft data and restrictions (wake turbulence),

• • Scheduling of events (list of flights), and

• • Weather considerations (reduced visibility operations).

6.3 OutputOutput data is produced in a report format which may also be converted into charts andgraphs. The data available from SIMMOD includes:

6.4 Airfields, which includes:• Runway utilisation,

• Ground delays at gates, holding points or during taxiing,

• Average times for completing ground movements.


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6.5 Sectors, which includes:• Total number of aircraft that crossed the sectors within a specified time

period,

• Maximum number of aircraft in each sector's area of responsibility at anyone time within a specified time period,

• Average flight times for the sectors,

• A workload index for the sectors, and

• Number of aircraft in level flight, climbing or descending for each sectorwithin a specified time period.

6.6 Points, which includes:• Rate of traffic flow over points,

• Number of aircraft climbing, descending or in level flight at a point,

• Number of potential conflicts that will require ATC intervention.

6.7 Routes, which includes:• Average flight times on each route, and

• Number of aircraft on each route.

6.8 Simulation AnimationIn addition to the output data, the SIMMOD post-processor module produces ananimated high resolution colour display of the simulation. All aircraft can be displayedduring all stages of flight, or ground movement, following procedures defined in the inputdata.

During the animation run various items can be analysed:

• • Evolution of a traffic situation and traffic flow,

• A visual check of the simulation's realism,

• • Verification that procedures defined for the model do not violate thedefined separation specifications, and

• • Areas of scheduling congestion can be located.

6.9 Disadvantages - LimitationsSIMMOD is designed as a "quick look" simulation tool and has the followinglimitations:

No resolution of conflicts during a simulation by changing an aircraft's level, and

A global view only, no detail regarding an individual controller or operating position.


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7. ANNEX B - Workload Calculations -DescriptionThe Workload Index is an attempt to assess the workload in a sector by attributingdifferent weightings to various characteristics of the traffic in the sector. Theworkload index values produced for this report originate from a partialimplementation of the MBB2 system.

The MBB system is based on the R/T load observed in ATC sectors. From theseobservations, a series of parameters were developed to indicate the relativeimportance of the characteristics of the traffic giving rise to this load.

In a SIMMOD study it is not possible to determine all the conditions necessary toapply all of the thirteen parameters defined by the classic method for estimatingsector workloads. However it is possible to determine 7 of them:

• A scheduled flight transiting the sector.

• A climbing or descending flight.

• A flight transiting the UIR/FIR.

• A flight entering or leaving a TMA.

• A radar vectoring action on a flight.

• A flight being held at a designated point.

• A potential conflict detected and resolved.

For the purposes of a SIMMOD study these parameters are implemented as definedbelow:

• For each aircraft which at any moment during the specified time period iswithin the sector’s area of responsibility: Add 1 work unit.

• If the flight’s altitude at the sector entry point is not equal to the altitude atthe sector exit point: Add 0.24 work units.

• If the flight occurs solely in the UIR or FIR: Add 0.26 work units else 0.38work units respectively.

• For each SIMMOD control action (speed up, slow down or radarvectoring): Add 0.3 work units.

• For Each SIMMOD hold at a specific point: Add 0.6 work units.

• For each potential conflict detected and resolved by a control action(speed up, slow down, vectoring or hold - whether at a specified holdingpoint or not): Add 1.4 units of work.

2 MBB as defined in the report “Methods for the Determination of the Control Capacity ofATC Services” by Klaus Brauser. Messerschmitt-Bolkov-Blohm. Gmbh. 14/11/75.


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Whilst the system must necessarily be viewed as an approximation, it does give anindication of the density of the traffic in a sector and the complexity of the controllers’tasks. As such, the values quoted in this report can reasonably be used forcomparing the workload between sectors.

EUROCONTROL · 2008-09-15 · EUROPEAN ORGANISATION FOR THE SAFETY OF AIR NAVIGATION EUROCONTROL...

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