Evaluation of delegation of sequencing operations to the flight crew

2000-01-5566

Evaluation of delegation of sequencing operations to the flightcrew from a controller perspective – Preliminary results

Isabelle GRIMAUD*, Eric HOFFMAN, Karim ZEGHAL†

EUROCONTROL Experimental Centre, BP 15, F-91222, Bretigny, France*CRNA Sud-Est, rue V. Auriol, F-13617 Aix-en-Provence, France

†Steria Transport Division, BP 58, F-78142 Vélizy, France

Copyright © 2000 EUROCONTROL Experimental Centre. Published by SAE International, and the American Institute of Aeronautics and Astronautics, Inc.with permission.

ABSTRACT

A simulation has been carried out to evaluate thedelegation of sequencing operations to the flight crewfrom a controller perspective. The airspace simulatedwas a part of the Paris terminal area, which is of one ofthe busiest in Europe. Six controllers from differentEuropean countries participated during two weeks (oneweek dedicated to sequencing operations, one for en-route that are not discussed here). For the controller,the expected gains mainly rely on a workload reductionthat was estimated through the number of instructionsgiven. An important decrease in the number ofinstructions was obtained with delegation. An initialestimation of the efficiency variation was made throughthe record of time, distance and fuel consumption. Aslight decrease emerges that was also suggestedgraphically on flown trajectories. A second session isplanned that will investigate the monitoring aspectstypically through detailed objective workloadmeasurements.

INTRODUCTION

Enhancing air traffic capacity while providing safetyimprovements constitutes the major challenge facing AirTraffic Management (ATM). However, the growthforecasts for air traffic in Europe and in the UnitedStates over the next fifteen years suggest that solelyimproving the ground component of ATM might not besufficient to achieve the required capacity at appropriatesafety levels. The development of a close co-operationbetween ground and airborne sides might be required toachieve this challenge. The delegation from thecontroller to the flight crew of some tasks related toseparation assurance is proposed to increase controlleravailability and flight crew situational awareness.Depending on traffic conditions and airspaceconstraints, this increased availability is expected to

provide safety improvements and to be converted intoenhanced traffic capacity or flight efficiency. It takesadvantage of emerging CNS/ATM technologies in pre-operational state – ADS-B or TIS-B [4] – along withadditional avionics such as a Cockpit Display of TrafficInformation (CDTI) [5] or an Airborne SeparationAssurance System (ASAS).

The delegation of separation assurance is envisaged foren-route airspace and for terminal areas. For aircraftwithin an arrival stream in a terminal area, thedelegation could consist in tasking the flight crew todetermine and perform the necessary speedadjustments so as to maintain a given separation to thelead aircraft. A series of studies dating back to thebeginning of the 80s aimed at capturing the essence ofin-trail following in terminal areas, from systemdynamics and pilot perspectives [1,2,6,7]. Later,merging operations have also been investigated [2].These studies carried out analytical works andsimulations using mathematical models, and pilot-in-the-loop experiments with cockpit simulators. The feasibilityof a self-spacing technique in term of dynamics wasdemonstrated: the separation can be accuratelymaintained by pilots from cruise to final approach fix,and no instability tendency occurs in strings of aircraft.However, an increase of workload in the cockpit clearlyappears thus raising the general issue of identifying thebest trade-off between controller and pilot workload. Asan initial step to address this issue, the task repartitionbetween controllers and pilots has to be defined and theoverall outcomes – benefits? – have to be evaluated.

From a controller perspective, one of the main issuesarising by the delegation is the capability to maintain anadequate mental picture of the traffic with delegatedaircraft. A pragmatic approach was chosen that startsfrom the analogy of visual clearances. More precisely,the task repartition relies on two key elements: a limited

delegation in which the controller leaves no more thanimplementation tasks to the pilot, and a flexible use ofdelegation allowing to select the level of task delegatedbetween monitoring up to implementation. This form ofdelegation has been defined both for sequencingapplications in terminal areas, and for crossing andpassing applications in en-route airspace [8]. A series ofsimulations has been carried out to evaluate theexpected benefits with a focus on the ground side. Theairspace simulated is a part of the Paris terminal areawhich is of one of the busiest in Europe. Six controllersfrom different European countries participated duringtwo weeks.

The article is organised as follows: the two next sectionsoutline the main principles of this form of delegation anddescribe the procedures. The two following sectionsdescribe the simulation characteristics and present thepreliminary results on sequencing applications.

PRINCIPLES OF DELEGATION

This section presents the key elements of the proposeddelegation, and their consequences from controller andpilot point of view. It also briefly outlines the procedures.

KEY ELEMENTS

The key elements can be summarised as follows:

No obligation of use: The delegation is a facilityprovided to the controller, and each controller has theoption to use it or not.

Upon controller initiative: The delegation is alwaysinitiated by the controller, who decides to delegate asituation if appropriate and helpful.

Visual clearance analogy: The delegation is applicablefor situations involving two aircraft. One aircraft –denoted subject – receives the delegation with respectto another one – denoted target.

Limited delegation: The delegation is limited to thetasks of monitoring and implementation of a solution.

Flexible use of delegation: The level of the taskdelegated can range from monitoring up toimplementation of a solution, and the controller has theresponsibility to select the appropriate level of task foreach situation.

One parameter delegated: In addition to a limiteddelegation, for the tasks that may require manoeuvringactions only one (exceptionally two) flight parameter isdelegated at a time.

CONSEQUENCES

No change in roles: Situation analysis, identification ofproblems, e.g. conflict detection, definition of solutions,and decision of delegation remain within role andresponsibility of the controller.

The controller keeps the initiative and overall authorityon situation management. The core roles and workingmethods of controllers and pilots remain unchanged.

Same working practices: The delegation can – andmust – be used in conjunction with current workingpractice. The delegation is considered as a new type ofATC instruction. It does not impact on controller’sdecision-making.

No change of responsibility: The delegation does notimpose any change of responsibility between controllersand pilots. The delegation can be considered as a newinstruction. The controller is responsible for providing anappropriate instruction that will ensure the separationand which is acceptable (flyable) by the pilot. The pilot isresponsible for following this instruction.

Predictability maintained: Furthermore, the limiteddelegation being restricted by the delegation of only oneparameter at a time, and using appropriate pilot reports,this should allow the controller to anticipate pilot futureactions and to predict future aircraft trajectories astoday.

Flexibility: The flexible use of delegation would provideflexibility to use the delegation under different conditionssuch as traffic density, airspace constraints, andpractice level. It would also enable a gradual confidencebuilding in the delegation. Indeed, these levels reflectincreased use in practice. Each controller should thusexperience his own “trade-off”.

PROCEDURE OVERVIEW

Applicability conditions: Prior to delegating, thecontroller must make sure that all applicability conditionsfor the envisaged delegation are respected. The respectof these conditions guarantees that the delegation issafe and beneficial. It should be noted that the higherthe delegation level, the more restrictive the applicabilityconditions are.

Delegation instruction: The delegation uses specificcontroller instructions to define the task delegated, andpilot reports to mark phase changes and the end ofdelegation.

Delegation phraseology: All the communicationsbetween controller and pilot required by the delegationuse radio-telephony, i.e. voice communication. A newphraseology is proposed.

Pilot agreement: The delegation requires theagreement of the pilot of the delegated aircraft1. Noagreement is required from the pilot of the targetaircraft, and no indication of his becoming a target isgiven.

Three phases: The delegation consists in three differentphases:

1. Identification phase in which the controller indicatesthe target aircraft to the pilot of the delegatedaircraft.

2. Instruction of delegation in which the controllerspecifies the task delegated to the pilot.

3. End of delegation which marks the completion of thetask delegated.

These phases are described in the following sections.

Interruption of delegation: The controller can interrupta delegation at any time. The pilot can interrupt adelegation in case of emergency only.

Transfer to next sector: A pair of target plus delegatedaircraft can be transferred to the next sector withoutneeding to cancel the delegation.

Additional instruction: During a delegation, thecontroller can give an additional instruction withoutcancelling the delegation if the instruction is compatible,i.e. if the flight parameter modified by the instruction(e.g. heading) does not affect the parameter delegated(e.g. speed). This is particularly envisaged for “direct-to”or “descent” for in-trail following.

Anticipation: There must be enough anticipation to setup the delegation process, specifically for highest levelsof delegation.

Task sharing: For the delegation aspects, a tasksharing between planning controller and tacticalcontroller is proposed: the planning controller willidentify the delegable situations, i.e. delegated aircraft,target aircraft and level of delegation. This task sharingfollows the trend emerging in current practices wherethe planning is preparing the analysis of the traffic andconflict detection for the tactical controller.

Technical assumption: For some applications, thetrajectory of the target aircraft must be predictable onboard the delegated aircraft. Aircraft receives flight stateinformation (position and velocity) of the surrounding

� Since the delegation is considered as a new ATC instruction,it could also be envisaged that a delegation cannot be refused,except for serious reasons due to emergency situations or on-board failure.

traffic through ADS-B or TIS-B. However, it is notassumed at present stage, that intent information suchas trajectory is received. For that reason, for thoseapplications, it will be required that the target aircraft isflying straight ahead.

APPLICATIONS

Two classes of application are considered:

� Crossing and passing applications in en-routeairspace. Three levels of delegation are proposedcorresponding to reporting, maintaining theseparation, and providing the separation (Table 1).

� Sequencing operations – merging and in-trailfollowing – in extended Terminal Manoeuvring Area(TMA). Three levels of delegation are proposedcorresponding to reporting, maintaining theseparation, and resuming then maintaining theseparation (Table 2).

Airspace Í En-route

Crossing and passingApplications Í

Delegation level Ï

Lateral Vertical

Report Report clear oftarget

Report clear oftarget

Maintainseparation

Resume navigation Resume climb

Provide separation Pass behind Pass below /above

Table 1. Crossing and passing applications.

Airspace Í Extended TMA

SequencingApplications Í

Delegation level Ï

In-trail Merging

Report Report in-traildistance *

Report mergingdistance

Maintainseparation

Remain behind Merge behind

Resume thenmaintain

separation

Resume thenremain behind

Resume thenmerge behind

Table 2. Sequencing applications. *Not available.

PROCEDURES FOR SEQUENCINGOPERATIONS

This section will describe the different phases of thedelegation:

1. Identification phase in which the controller indicatesthe target aircraft to the pilot of the delegatedaircraft.

2. Instruction of delegation in which the controllerspecifies the task delegated to the pilot. Theinstruction will be described for each application.

3. End of delegation which marks the completion of thetask delegated.

4. The interruption of delegation which may or may notoccur.

In the examples presented, DLH456 is the delegatedaircraft, and AFR123 is the target aircraft with 1234 asSSR code.

IDENTIFICATION PHASE

The identification of the target aircraft is the first phaseof the delegation procedure. The objective is to enablethe pilot to select and visualise the target aircraft on hisCockpit Display of Traffic Information (CDTI), uponcontroller request. The target aircraft is specified by thecontroller using an unambiguous identifier. In thefollowing, the SSR code is used as the identifier2.

The identification consists in three messages:

1. Controller identification message in which thecontroller indicates the identifier of the targetaircraft. For cross-check purposes, the controllercould also position the target, or request the pilot toposition it.

2. Pilot readback.

3. Pilot confirmation in which the pilot confirms theidentification of the target, and positions the target ifrequested by the controller.

The readback automatically implies the agreement ofthe pilot for the forthcoming delegation. If the pilotdecides – for any reason – to refuse the delegation, hemust say so instead of the readback.

� To avoid confusion, the callsign of the target aircraft cannotbe used as identifier. However since the SSR code will not beavailable in ADS-B messages, another identifier would berequired.

Phraseology: Two variants are proposed: either thecontroller positions the target or requests the pilot toposition it (cross check assured by the pilot). Therejection following identification is also proposed.

Identification with positioning by the controller:

Controller: "DLH456, select target 1234, (3 o’clock /right to left / 30 Nm / 1000ft above)"

Pilot: "Selecting target 1234, DLH456"

After pilot selection and identification on the CDTI:

Pilot: "Target 1234 identified, DLH456"

INSTRUCTION OF DELEGATION

The instruction of delegation is the second phase of thedelegation procedure. The objective is to specify to thepilot the task he has to handle. This task can range frommonitoring to implementation of a specified manoeuvre.The instruction of delegation consists in one controllermessage and requires pilot readback.

Only instructions for sequencing are presented. Foreach instruction, the following items are presented: abrief description of the application, task repartitionbetween the controller and the pilot, the parameterdelegated to the pilot, the applicability conditions, andthe phraseology.

REMAIN BEHIND

Description: The two aircraft are flying along the sametrajectory in cruise or in descent phase (Figure 1). Thedesired separation towards the lead aircraft is obtained.(The lead aircraft is the target, and the trailing aircraft isthe delegated one.)

Task repartition:

� The controller: indicates the desired separation tobe applied.

� The pilot: adjusts speed to maintain the desiredseparation.

Delegated parameter: Speed.

Applicability conditions: The two aircraft must flyalong the same trajectory.

The two aircraft must have compatible performances.

The two aircraft must have compatible speeds at start ofdelegation and during the delegation period.

The current separation must not be lower than thedesired separation.

AFR123235 ↓ 40

DLH456250 ↓ 41

DD

Figure 1. "Remain behind" scenario. D is the desiredseparation. (Colour convention applicable for figures 1to 4: black: actual situation of target aircraft; grey: initialsituation of delegated aircraft; dashed: predicted orpotential situation; green: controller instruction; blue:delegated instruction.)

Observations: To ensure compatible speeds at start ofdelegation, the controller may need to issue an initialspeed instruction either to the target or to the delegatedaircraft.

Aircraft should generally be at similar altitude. (This toensure compatible speeds during delegation.)

The descent clearance or the top of descent instructionshould be given to the delegated aircraft at appropriatetime. (This to ensure compatible speeds duringdelegation.)

A heading or a “direct to” instruction can be given to thelead aircraft. In that case, same instruction must begiven to the delegated aircraft. (This to ensure thattrajectories remain the same.)

This delegation can be applied from the cruise phasedown to the Initial or Final Approach Fix. The delegationcan start indifferently in cruise or in descent.

This delegation can be used for aircraft having differenttrajectories after a given point. In that case, thedelegation must end at or before that point.

This delegation can be given to chains of aircraft.

Phraseology: Two variants are proposed: the end ofdelegation relying either on the controller or the pilot.Only the variant with end of delegation by the controlleris presented:

Identification phase

Controller: “DLH456, behind target, remain 15Nmbehind, (until further advice)”

Pilot: “Remaining 15Nm behind target, DLH456”

Once the controller decides to end delegation:

Controller: “DLH456, end delegation, speedinstruction”

RESUME THEN REMAIN BEHIND

Description: The two aircraft are flying along the sametrajectory in cruise or in descent phase (Figure 2). Thedesired separation is not obtained, the controller thushas to give a heading instruction.

Task repartition:

� The controller: gives a heading instruction to providethe desired separation towards the lead aircraft;Indicates the desired separation to be applied.

� The pilot: figures out and reports when reaching thedesired separation, then resumes navigation behindlead aircraft, and then adjusts speed to maintain thedesired separation. (This delegation becomes a“Remain behind”.)

DD

AFR123235 ↓ 40

DLH456250 - 41

DD

Figure 2. "Resume then remain behind" scenario.

Delegated parameter: Time to manoeuvre, thenheading and speed, then speed.

Applicability conditions: Identical to “Remain behind”plus: there must be no restricted manoeuvring airspaceduring the manoeuvring period – resume navigationbehind lead aircraft: no potentially interfering aircraft, nodanger area proximity.

Observations: Identical to “Remain behind”.

Phraseology: Similarly to the “Remain behind”, the endof delegation relying either on the controller or on thepilot, two variants are proposed. Only the first one ispresented:


Controller: “DLH456, heading instruction then behindtarget (proceeding direct to WPT), resume 15Nmbehind, until further advice”

Pilot: “Heading instruction readback then will resume15Nm behind target (proceeding to WPT), DLH456”

Once desired separation is 15Nm:

Pilot: “DLH456, 15Nm behind target, resumingbehind (to WPT)”

MERGE BEHIND

Description: The two aircraft are flying along mergingtrajectories in cruise or in descent (Figure 3). Thedesired separation is obtained at the merging point.

Task repartition:

� The controller: indicates the desired separation tobe applied.

� The pilot: adjusts speed to maintain the desiredseparation at the merging point, then, after passingthe merging point, adjusts speed to maintain thecurrent desired separation. (This delegationbecomes a “Remain behind”.)

AFR123235 ↓ 40

DDWPT

DLH456250 ↓ 41

Figure 3. "Merge behind" scenario.

Delegated parameter: Speed.

Applicability conditions: The two aircraft must flystraight to the merging point.

After the merging point, aircraft must fly the sametrajectory.



Observations: Identical to “Remain behind” plus: incase one of the two aircraft is not flying straight to themerging point, a direct to the merging point must begiven.

Phraseology: Similarly to the “Remain behind”, the endof delegation relying either on the controller or on thepilot, two variants are proposed. The first one is:


Controller: “DLH456, behind target, merge to WPT tobe 15Nm behind”

Pilot: “Merging to WPT to be 15Nm behind target,DLH456”

RESUME THEN MERGE BEHIND

Description: The two aircraft have to fly along same ormerging trajectories in cruise or in descent (Figure 4).The desired separation at the merging point is notobtained, the controller thus has to give a headinginstruction.

Task repartition:

� The controller: gives a heading instruction to providethe desired separation to the lead aircraft; indicatesthe desired separation to be applied.

� The pilot: figures out and reports when the predictedseparation at the merging point would reach thedesired separation, then resumes navigation to themerging point, and then adjusts speed to maintainthe desired separation at the merging point. (Thisbecomes a “Merge behind”.)

Delegated parameter: Time to manoeuvre, thenheading, then speed.

Applicability conditions: The target aircraft must flystraight to the merging point.

After the merging point, aircraft must fly the sametrajectory.



There must be no restricted manoeuvring airspaceduring the manoeuvring period – resumes navigation tothe merging point: no potentially interfering aircraft, nodanger area proximity.

AFR123235 ↓ 40

DLH456250 ↓ 41

WPT

DD

Figure 4. "Resume then merge behind" scenario.

Observations: Identical to “Remain behind” plus: incase the target aircraft is not flying straight to themerging point, a direct to the merging point must begiven.

Phraseology: Similarly to the “Remain behind”, the endof delegation relying either on the controller or on thepilot, two variants are proposed. The first one is:


Controller: “DLH456, heading instruction then behindtarget, merge to WPT to be 15Nm behind”

Pilot: “Heading instruction readback then will mergeto WPT to be 15Nm behind target, DLH456”

Once merging distance is 15Nm:

Pilot: “DLH456, merging distance to WPT 15Nm,merging behind target”

END OF DELEGATION

The end of delegation corresponds to the completion ofthe delegated task. Depending on each application, itoccurs either upon pilot report or controller instruction.More specifically, the end of delegation is marked:

� For crossing and passing applications, by the “clearof target” report

� For sequencing operations, by the “passingwaypoint” report or the controller new instruction(depending on initial instruction of delegation).

INTERRUPTION OF DELEGATION

The delegation can be interrupted by the controller atany time and for any reason, e.g. situation morecomplex than expected, additional traffic.

The delegation can be interrupted by the pilot only incase of emergency3, e.g. CDTI failure, meteorologicalcondition degradation such as storm cell encounter.

DESCRIPTION OF THE SIMULATION

BACKGROUND AND OBJECTIVES

A first small scale real-time experiment took place inJune 1999 [8]. The main objective was to collectfeedback from controllers and pilots in order to assessthe operational feasibility and potential interest of theconcept. Due to the assumptions made – simple ATCenvironment, small number of participants and limitedoccurrences of potential delegations – no quantitativemeasures could be made. The results were qualitativeindications gathered through questionnaires anddebriefings, with an inherent subjective component incontroller and pilot responses. The overall feeling aboutthe method was “promising with a great potential”. Thismethod could allow an increase in controller availability.In addition, the flexible use of delegation would providethe expected flexibility to use the method under differentconditions and would also enable a gradual confidencebuilding. It has been observed however that the nonrespect of the applicability conditions of the methodcould result in an increase in workload andcommunication.

The objective of the present larger scale experiment isto validate the concept in a more realistic environmentand to evaluate the expected gains from a controllerperspective. For the controller, the expected gainsmainly rely on a workload reduction that was estimatedthrough the number of instructions given. It should benoticed that the monitoring aspects also impacting onworkload were not yet evaluated. (A measurementbased on eye-tracking will be performed during the nextsession in November '00.) An initial evaluation on theimpact on flight efficiency is proposed through themeasurement of time, distance, and fuel consumption.

The differences between the '99 experiment and thisone mainly rely on three elements: all aircraft areequipped to receive delegation, two sectors aresimulated at a time, and a high density airspace is used.

� The interruption by the pilot must be restricted to suchsituations since the backup intervention for the controller mayinduce additional workload and stress.

SIMULATION ENVIRONMENT

The simulation was split into two distinct sessions of oneweek each: one for sequencing applications and one forcrossing and passing applications. From a controllerperspective and due to the short training period thissplitting was thought to minimise risk of confusion in theuse of the two classes of application. From anevaluation perspective, this splitting allowed for aseparate analysis thus a better understanding of theoutcomes for each class.

Two distinct organisations were thus simulated:

� An extended Terminal Manoeuvring Area (TMA)exhibiting sequencing situations from cruise to theInitial Approach Fix (IAF).

� An en-route airspace exhibiting crossing andpassing situations.

The simulated airspace was a part of the Paris SouthEast area which was thought to represent a typical highdensity airspace (Figure 5). Four existing sectors wereselected. Two criteria were considered for selection:firstly the sectors should have arrival and overflyingflows to be used for both organisations. Secondly, thesectors should be long enough to allow for a significantduration of the delegations. Sectors should also be largeenough since anticipation and space are needed to takemaximum advantage of the delegation (Typically to setup the delegation process, to give "resume" pointwithout requiring coordination, and to let aircraftmanoeuvre). The four sectors were then combined intotwo measured sectors. The combination was differentfor each organisation. For extended TMA, the grouping– which is applied in the reality – allowed for a handlingof a majority of flights from cruise to IAF by the samesector. Thus, the delegations process could besimulated and analysed during a significant period oftime. In addition, direct instructions to IAF that wereintensively used specifically for merging applications didnot require any coordination.

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Figure 5. Airspace dedicated to sequencing applications. Flights landing at Charles de Gaulle (LFPG) or Le Bourget(LFPB) from the South-East arrive through AR1 and are transferred to Roissy TMA (feed sector) over SUSIN (IAF) atFL80. Flights landing at Orly (LFPO) from the South-East arrive through AO1 and are transferred to Orly TMA (feedsector) over MEL (IAF) at FL70.

The two measured sectors plus two feed sectors weresimulated at a time. Each measured sector was mannedwith two controllers: one planning and one tactical. Eachfeed sector was manned with one controller. For eachorganisation, each controller was specialised on onemeasured sector and simulated as tactical controller onthis sector: two training exercises plus two halfmeasured exercises. Each measured exercise wassimulated twice: once without the use of delegation,once with it. The duration of each measured exercisewas two hours. No specific tool was provided to thecontrollers.

On each sector, the aircraft were handled by twopseudo-pilots. All the aircraft were ASAS equipped andthus capable to receive delegations. When receiving adelegation instruction (via radio-telephony), the pseudo-pilot activated the corresponding function performingautomatically the separation assurance.

The traffic samples were derived from two trafficrecordings performed in the Paris Area Control Centrecovering traffic flow in the morning and in the afternoonon the 13th of October 1999. For the extended TMAorganisation, the traffic was mainly composed of arrivalflows. The arrival traffic was slightly increased andadjusted to create clusters of up to five aircraft, and tohave similar traffic load for both sectors. Thesequencing of these clusters could lead to continuousstreams of aircraft (Figure 7). The resulting traffic wasclose to a real high density traffic and validated by aParis Controller.

PRELIMINARY RESULTS

For the following results, a measured period of twohours has been chosen for each exercise startingapproximately 15 min after the beginning of theexercise. A total of three exercises (denoted Ex1, Ex2and Ex3) have been simulated twice: without and withdelegation. Ex2 and Ex3 were based on the same trafficsample.

The number of arrival flights and the sector load areindicated below for each sector (Tables 3, 4). Thenumber of arrivals is identical for both sectors. Thetraffic load was lower for AR due to more overflyingtraffic in AO. However due to the complexity of the routestructure the resulting workload for AR was consideredas equivalent to that of AO.

Exercise IAF Max Min Mean StdevEx1 47 19 7 13 3Ex1 ASAS 47 19 5 13 3Ex2 48 16 4 10 3Ex2 ASAS 48 17 4 11 3Ex3 48 20 5 11 4Ex3 ASAS 48 21 5 12 4Table 3. Number of aircraft in sector AO.

Exercise IAF Max Min Mean StdevEx1 47 15 6 10 2Ex1 ASAS 47 15 4 10 2Ex2 48 15 5 10 2Ex2 ASAS 48 14 5 9 2Ex3 48 16 4 11 3Ex3 ASAS 48 15 5 10 2Table 4. Number of aircraft in sector AR.

The variation of workload with and without delegation isestimated through the number of manoeuvring actionswhich is listed below (Tables 5, 6). Standard instructionsof separation and delegation instructions are indicatedby type along with the total number. (The "reportmerging distance" application was not used and istherefore omitted.)

In order to compare the variation in the number ofmessages, the number of target selections is alsoindicated. The transfer instructions have been omittedsince transfer to next sector induces the same numberof messages with and without delegation.

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Heading 46 21 56 16 50 13

Direct 39 36 58 23 57 44

Speed 58 8 104 22 64 26

Level 70 55 70 62 58 61

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Remain 10 9 4

ResumeThenRemain 2 5 1

Merge 6 15 20

ResumeThenMerge 14 17 16

EndDelegation 7 9 4

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SelectTarget 35 42 40

Table 5. Instruction number for AO.

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Heading 68 35 48 24 105 46

Direct 51 29 63 36 66 34

Speed 70 16 110 7 140 16

Level 113 79 78 62 88 64


Remain 3 6 17

ResumeThenRemain 0 0 0

Merge 14 24 11

ResumeThenMerge 21 22 24

EndDelegation 4 4 9


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SelectTarget 39 52 49

Table 6. Instruction number for AR.

Some differences in the number of instructions can benoticed among exercises but may rely on differenttechniques of control. However, no significant trendemerges. As discussed previously, sector AR requiresapparently more manoeuvring instructions.

The summary of the number of instructions is given inTable 7 and in Figure 6. The most important result is thesignificant decrease in the number of instructions withdelegation (28% for AO, 34% for AR). The majordecrease results from the reduction of speedinstructions. It should be stressed that the reduction ismore important for AR sector requiring more instructions(vectoring and speed). The reduction of instructions isthought to reflect a reduction of the task of control. As aresult of the reduction of the manoeuvring actions,particularly speed and heading changes, trajectoriesbecomes more stable (see also Figure 8). Less time-critical "guiding" to maintain separation is necessary.

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Heading 51 (5) 74 (29) 17 (4) 35 (11)

Direct 51 (11) 60 (8) 34 (11) 33 (4)

Speed 75 (25) 107 (35) 19 (9) 13 (5)

Level 66 (7) 93 (18) 59 (4) 68 (9)


Remain 8 (3) 9 (7)

ResumeThenRemain 3 (2) 0 (0)

Merge 14 (7) 16 (7)

ResumeThenMerge 16 (2) 22 (2)

EndDelegation 7 (3) 6 (3)


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Table 7. Summary of instruction number for allexercises (figures in brackets represent standarddeviation).

0

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Figure 6. Summary of instruction number.

Concerning the number of messages exchanges (i.e.target selections included), a decrease is also visible(18% for AO and 25% for AR). However, while areduction of the frequency occupancy was expected andfelt by all the controllers, no significant variation hasbeen recorded. Technical problems with the voicerecording may explain this result.An initial estimation of the efficiency variation was madethrough the record of time, distance and fuelconsumption. Total and mean values are indicatedbelow (Tables 8, 9). A slight decrease emerges withdelegation from the three parameters. The flightefficiency is also graphically suggested on flowntrajectories (Figure 8): with delegation trajectoriesbecome straighter.

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Ex 1 34:52:30 13314 838696Ex 1 ASAS 33:24:35 13026 810361Ex 2 37:05:55 13329 764981Ex 2 ASAS 34:28:35 13060 754834Ex 3 35:42:50 13353 754288Ex 3 ASAS 33:39:45 13025 737003

Table 8. Total efficiency figures.

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Ex 1 0:22:16 142 8922Ex 1 ASAS 0:21:20 139 8621Ex 2 0:23:11 139 7969Ex 2 ASAS 0:21:33 136 7863Ex 3 0:22:19 139 7857Ex 3 ASAS 0:21:02 136 7677

Table 9. Mean efficiency figures.

CONCLUSION

In the scope of evaluating the benefits of the delegationof sequencing operations to the flight crew, a simulationwith controllers has been carried out. An existingorganisation including two measured sectors with arrivalflights was simulated. From a controller perspective, thedelegation allows for a significant reduction in thenumber of instructions given. This is thought to reflect apossible workload reduction. In terms of efficiency, time,distance and fuel consumption are also reduced, and itappears also that trajectories become more stable. Inthis paper, only raw quantitative results have beenpresented. Detailed analysis including the controllerquestionnaires is forthcoming. It should provide moreinsights in the actual impact of delegation on thecontroller working methods, in particular modificationand/or rescheduling of tasks. A second session isplanned for November’00, and the impact of thedelegation on the monitoring task will be investigated. Amore detailed focus will be put on flight deck issues. Theimpact of non-nominal situations on delegation will beinvestigated in future experiments.

Figure 7. Example of planned (upper) and flown traffic (lower).

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Figure 8. Trajectories without delegation (upper) and with delegation (lower).

ACKNOWLEDGEMENTS

This project is sponsored by the EEC and theEurocontrol EATMP SCS Unit. The authors wish tothank Robert Graham (EEC) and Jean Lamonoca(CRNA Sud-Est, France) for their support. Thanks toAnne Cloerec, Jean-Pierre Nicolaon, Robin Deransy,Nathalie de Beler, and Carol Sheehan for their help andcomments. Thanks to Dominique Seiler, Jose Seixo,Franck Ballerini and Sébastien Lièvre for their technicalassistance. Thanks to Josée Bralet, Aymeric Blanc,Colette Lambert, Franck Loubier, and ThibaultSchneider for their skillful flying of the aircraft during thesimulation. And last but not least, thanks to ClaudioColacicchi and Alberto Valentini (ENAV, Italy), FernandoCambraia and Luis Martins (NAV-EP, Portugal), MarkAsquith and Ian Ralph (NATS, U.K.) for their enthusiastparticipation and their fruitful comments.

REFERENCES

The materials used for presentation and training duringthe simulation are available atwww.eurocontrol.fr/projects/freer/index.htm

1. Kelly, J.R., Abott, T.S., In-trail spacing dynamics ofmultiple CDTI-equipped aircraft queues, NASA TM-85699, 1984.

2. Pritchett, A.R., Yankosky L.J., "Simultaneous designof cockpit display of traffic information and air trafficmanagement procedures", SAE Transactions –Journal of Aerospace, 1998.

3. Pritchett, A.R., Yankosky L.J., "Interaction of cockpitdisplay of traffic information and air trafficmanagement procedures", IEEE/AIAA DigitalAvionics Systems Conference, St. Louis MO, 1999.

4. RTCA SC-186, Minimum Aviation SystemPerformance Standards for Automatic DependentSurveillance Broadcast (ADS-B), DO-242.

5. RTCA SC-186, Guidance for Initial Implementationof Cockpit Display of Traffic Information, DO-243,1998.

6. Sorensen, J.A., Goka, T., "Analysis of in-trailfollowing dynamics of CDTI-equipped aircraft",Journal of Guidance, Control and Dynamics, vol. 6,pp 162-169, 1983.

7. Williams, D.H., "Self-separation in terminal areasusing CDTI", Proceedings of the Human FactorsSociety Annual Meeting, 1983, pp 772-776.

8. K. Zeghal, E. Hoffman, J.-P. Nicolaon, A. Cloerec, I.Grimaud, “Initial evaluation of limited delegation ofseparation assurance to the cockpit”, SAE/AIAAWorld Aviation Congress, San Francisco, October1999.

Documents

Evaluation of delegation of sequencing operations to the flight crew