If you have read my article on the New Directions for Airport Collaborative Decision Making (CDM), you will be interested in this narrative description of the envisaged working of the expanded CDM concept. I do strongly recommend that you read the New Directions article first!
The example used is that of a departing flight. It is not a formal use-case as such and it focuses on the most important new features only. The scenario does not aim to be all-encompassing but sufficient detail is provided to enable readers to get a better understanding of the novel applications of CDM. A number of new services are mentioned in this scenario which are in addition to those mentioned in the original article. Their role is self explanatory but if you have any question, please write a comment and I will explain things in more detail.
Scenario assumptions
Airport – operational characteristics
The scenario is set at a busy European airport, the hub of a network carrier and served also by several low-cost airlines.
Three runways are available of which the two parallel runways are in use in the scenario, one for landing, the other for take-off.
The terminals and aprons are located such that no runway crossing is necessary for departures or for arrivals.
De-icing services are provided by a company specialised in this activity and which is independent of the ground handling companies.
The handling company in the scenario is in competition with two other similar enterprises, all three providing full service to their clients.
The airport has implemented A-SMGCS Level 2, Multi-Lateration based surveillance equipment and gate-link facilities. Appropriate air/ground digital link services (e.g. Pre-departure Clearance and D-Taxi) are in use.
The Approach Control Unit and the Aerodrome Control Tower serving the airport have shared, legacy arrival and departure managers, which however have been updated to accept Trajectory Based Operation (TBO) type (more accurate and detailed) information.
Airport – CDM characteristics
All partners participate in CDM and:
• CDM is linked to the network manager and is able to handle FUM/ DPI messages
• all new concept elements are implemented, including the elimination of the artificial airside/groundside boundary
All partners, including those with facilities that are not on the airport (e.g. taxi company, railway operator, etc.) are part of the net-centric environment.
The airport offers comprehensive Timely Passenger Delivery Service (TPDS) to the airlines requesting it. The actual provision of the service has been contracted to a company specialised in this kind of support.
Airport – passenger screening characteristics
The airport has one centralised Passenger Screening facility in each terminal, with lanes opened according to demand. The total number of lanes
available in the terminal that is the subject of this scenario is not able to accommodate more than about 80 % of peak demand (i.e. waiting time exceeds the agreed maximum).
Each Passenger Screening facility has two lanes for conducting extra checks on selected passengers. These are equipped with full body scanners.
Passengers approach the Passenger Screening facilities from a concourse that is off-limits to non-travellers.
100 % screening of hold baggage has been implemented in accordance with the applicable European directive.
At the time of the scenario the airport security status is red, resulting in more specially selected passengers and more thorough checking.
Schengen and non-Schengen flights depart from different areas and identity control is implemented before the Passenger Screening facility for non-Schengen flights and passengers are required to show their boarding pass before accessing the concourse and the Passenger Screening facility.
Airport – access characteristics
The airport is served by train, taxis and two lines of the Municipal Bus Company. It also has sufficient capacity for both short and long term parking of private cars. In spite of the train and bus connection, the majority of passengers (80+ %) arrive by car (private or taxi).
The airport is reached via a four-lane highway which connects to one of the major motorways. This motorway is subject to frequent delays and the airport highway contains a bridge which is often icy in winter (environmental constraints limit the use of salt in the area), causing frequent accidents.
At the time of the scenario, a fender-bender accident on the airport highway slows traffic to a crawl. Trains are running irregularly due to industrial action announced a week earlier.
Airport – meteorological characteristics
Late November, mid-morning, freezing rain, sleet, low visibility. The runways are being closed alternatively to check the friction index and to remove contaminants when necessary.
Airport – passenger amenities characteristics
The airport is renowned for its shopping arcades, a separate one serving each terminal. Making full use of the world famous products of the region, several boutiques sell these with a good selection of other merchandise also.
A selection of local culinary delights is available in the several restaurants placed strategically near the shopping areas. Their motto: “We are the best place to eat in town… and there is even an airport nearby!”
Wireless internet is available only in the shopping areas but there are “business islands” with power outlets and desks specially shaped to easily accept laptops of various sizes. Internet is free but there is a small charge for using the printers.
Passengers are obliged to pass through the shopping areas in order to reach their gates.
Airline characteristics
The airline operating the flight in the scenario is a network operator with extensive intra-European flights feeding its trans-Atlantic operations to the USA, Canada and the Caribbean area.
The intra-European flights have an on-time performance of 70 %.
The airline is a user of the Timely Passenger Delivery Service provided by the airport (via its contracted partner).
The airline is a member of a major alliance.
At this particular airport, all their ground handling is provided by one of the three competing companies.
Flight planning is provided for the airline by a commercial organisation that is part of the net-centric environment. The airline does have its own AOC. The division of responsibility between the pilot in command and the flight dispatch officer assigned to the flight reflects the new principles, where the pilot is responsible for decisions affecting the safety of the flight but the AOC is in command of all decisions concerning the commercial aspects of the flight.
Flight characteristics
The flight is an intra-European operation, departing from this busy airport to the airline’s main hub. Both airports are located in the Schengen-area.
The aircraft has landed being 15 minutes behind schedule. The turn-round time is 45 minutes.
Passengers are allowed to check-in either max. 30 hours prior to scheduled departure via internet or within 3 hours at the airport. Airport check-in can be at a self-service kiosk or agent assisted. Baggage drop-off for internet check-ins is serving all flights of this airline.
Aircraft characteristics
The aircraft concerned is a modern narrow body twin-engine jet. It is equipped with ADS-B out on 1090 MHz Extended Squitter as well as
air/ground digital link capability, with all the LINK2000+ services implemented (including D-TAXI). The cockpit has a Class 2 EFB which has been updated to display information related to CDM. The aircraft is able to use the gate-link facility while at the boarding gate.
Institutional, regulatory and implementation environment
At the time of the scenario, CDM has been implemented in Europe. The implementation program was co-ordinated by EUROCONTROL and it was fully supported by major associations like ACI-EUROPE, IATA, AEA, ELFAA and CANSO. This wide-spread support was based to a very large extent on the Cost/Benefit Analysis and subsequent business cases developed to support a favourable decision.
The FAA was also involved as an observer and advisor.
Scenario – summary description
The scenario uses one business class passenger checking in at home as the focal point, tracking his interaction with the passenger and baggage flow processes and the services being applied to those processes. Relevant aspects of the turn-round process are described when they are of concern to this extended form of CDM.
Scenario in detail
Aircraft operator planning
Flight BSX120 is the second rotation of this particular aircraft that day. Three more are planned. The first rotation was completed on schedule and the outbound leg of the second departed 5 minutes behind schedule.
The return leg of this trajectory carries a Very High Value tag (the 5th Dimension of the trajectory refers) in view of the large number of transfer passengers booked on it. This tag was determined by the aircraft operator, using the criteria agreed under the CDM implementation program and was added to the trajectory description when it was published.
The Airport Status Report Service (ASTRES) of the destination airport had published several warnings for the day. The first one originated 7 days earlier when the industrial action of the train drivers was first announced. The latest came on the day of the operation and was triggered by the prevailing meteorological conditions as well as the automated report from the Passenger Flow Information Service (PFIS). This latter reacted to the news of the accident on the airport access road, flagging up the disruption of the passenger flow towards the airport.
The airline dispatcher assigned to flight BSX120 was using the airline version of the net-centric trajectory planning end-user application which, as a subscriber to ASTRES and PFIS from all the airports served by the airline, was able to collate and automatically evaluate all the published information, generating appropriate advice to the dispatcher in respect of eventual necessary changes to the trajectory. In this particular instance, no changes were recommended but the trajectory value was published earlier to ensure proper planning at the airport where the return leg will originate.
Passenger check-in
Mr. C. D. Mariani, a busy executive of a mid-size company travelling home on BSX120 used the airline’s internet check-in facility (available from 30 until 1 hour before departure) to check in, starting the transaction 2.5 hours before departure. He indicated to the airline that he would have one piece of baggage to check on arrival at the airport. In the process, he was offered a choice to receive updates on his flight via a variety of delivery methods (text message, email, and push-email. He was also invited to indicate his selected method of accessing the airport. The choice to decline was prominently displayed in both cases together with a short explanation why this information was useful. The system only asked for the method of travel to the airport and not its origin. This type of remote interaction with the passenger was designed to avoid privacy issues. Mr. Mariani accepted the notifications, selecting push-email and he also selected “Taxi” when asked for the method of travel. With his Smartphone permanently on-line to the Internet, Mr. Mariani will receive the email notifications without having to log in to his email account.
The underlying application of the check-in web site immediately displayed a warning about the need to expect longer transit times to the airport, due to the accident. Had Mr. Mariani selected “Train”, he would have been informed of the need to choose an alternative solution because of the industrial action by the train drivers. Had he decided not to indicate his method of travel, generic messages covering all cases would be displayed.
The application is using information from ASTRES and PFIS.
Since all four taxi companies serving the airport are partners in the net-centric environment, Mr. Mariani’s selection of “Taxi” was noted by their systems also and they returned information containing the expected wait time and the phone numbers to call a cab, all of which was displayed on the site. This latter feature is time-dependent and does not trigger if the time until departure is more than a certain number of minutes.
Transit to the airport
Mr. Mariani had called a taxi and started the trip towards the airport in what would normally be plenty of time. However, because of the unreliable train service, there are more cars on the road than on other days, slowing progress. The effects of the earlier accident can still be felt.
The taxi company’s own vehicle tracking system noted when Mr. Mariani’s cab started its journey towards the airport. The tracking system was aware of the problems on the airport access road and had already increased the time before that particular car would be available for another fare. However, the system now noted that progress was even slower than expected. Together with similar information from scores of other taxis heading towards the airport, the delay information now exceeded the predetermined warning limit and the taxi company published a Delay Status Airport Access Report. From this moment onwards, all services and end-user applications which were subscribers to information on the airport access road status took into account one more delay report. One more, since other taxi companies and organisations which have published such information were also contributing to the shared situational awareness. One of the services that picked up the new report was the Passenger Flow Information Service (PFIS) at the airport.
Airport planning – general
The trajectory and associated flight data representing BSX120 has been available in the airport planning system for several months. It was described in the form of a 5 dimensional business trajectory (3 spatial dimensions, 1 time dimension and 1 economic value dimension) and a set of flight data, together which described the aircraft operator’s intentions, geared for best business outcome of the flight. As the actual date of the flight approached, details of the description, including the trajectory dimensions, were progressively refined. Some of these refinements actually reflected constraints and the aircraft operator’s response to them, to ensure that the trajectory would still be manageable in the expected and then actual state of the ATM network.
In the net-centric environment, which the airport is a part of, all partners from the airport operator via ATC to the aircraft operator share the same situational awareness. They are using the same set of flight and ATM network data presented according to their individual needs but always resulting in the same overall picture. The different partners are able to manipulate the trajectory/flight data depending on their particular authorisation but the information sharing rules (early versions of the forthcoming SWIM-based arrangements) ensure that all interventions are within the framework of the collaborative decision principles. These principles as well as the content of the trajectory/flight data and the different authorisations were agreed (in some cases provisionally) as part of the institutional framework established for CDM.
As noted earlier, the Airport Status Report Service (ASTRES) had already published its warning about the possibility 
of major trajectory distortions due to weather and the airport access difficulties, both of which were going to impact mainly the time dimension (since it was not expected that aircraft would need to divert to alternate aerodromes). With more bad news coming in through the Passenger Flow Information Service (PFIS), ASTRES incremented its warning level by 1 (even more serious distortions).
The Passenger Flow Information Service (PFIS) in the meantime is busy collecting and interpreting the passenger movement data it has available. In the net-centric environment, it has access to the occupancy of the airport parking garages and the in and out movement of the vehicles, the rate of returns at the car-rental companies, the total number of passengers expected at the airport per hour and the numbers actually processed, delays on the access roads, public transport situation, etc. PFIS is able to generate very accurate, real-time passenger flow information and compare it to the planned flow levels. When there is a discrepancy, like on the day of Mr. Mariani’s flight, PFIS publishes appropriate warnings showing, for instance, how the passenger flow-through demand peaks shift along the time-line and in space (terminals, gates, etc.). At the Passenger Screening service, ID control providers, passenger handling agents, the restaurants and shops, everywhere where end-user applications are subscribers to the PFIS warnings intelligent and context sensitive advice is generated with a view to optimising the operations concerned (e.g. open more Passenger Screening lanes, check-in counters, etc.).
On this particular day, triggered by PFIS, the various organisations have determined that there will be an unplanned peak in passenger arrivals in the period 2 hours before BSX120 is due to depart. Based on the recommendations of their end-user applications, and using their ability to make decisions collaboratively via the shared information environment, the partners agree the mitigating measures. More Passenger Screening lanes will be opened although the extra security measures cannot be suspended. It is determined (in part using data on internet check-ins already done) that the check-in kiosks at the airport will probably slow down the passenger flow. All in all, the airport expects a temporary passenger handling capacity shortfall up to 15 % in Mr. Mariani’s terminal. Empirical data held at the CDM data base shows that this translated to maximum 15 minutes delay in the average passenger’s progress from first entering the airport until reaching the boarding gate area. Passenger Flow Information Service (PFIS) notices when this result is published by the airport operator’s planning application and a further generic warning reflecting this new element is published by PFIS. Several mitigating actions are introduced, some automatically. An extra number of traditional check-in desks are manned and extra personnel assigned to the check-in area to guide passengers to the alternative check-in facilities to minimise queues; the Passenger Screening service reacts by ensuring that there are sufficient lanes open to keep the delay there to the minimum; the list of flights whose passengers will receive additional prompts to proceed swiftly to the gate is updated.
Aircraft operator planning
The operator of BSX120 is relying on the airline planning end-user application to maintain their awareness of the ATM network and in it the trajectory/flight data of BSX120. Information from ASTRES and PFIS feed into the same application.
The aircraft operator has already noticed that the time-dimension of the trajectory of the incoming flight has been modified and that the on-ground milestone in CDM is now shown as 20 minutes late. With the very short turn-round, it is not likely that the delay can be recovered.
In the meantime, the aircraft operator is aware that a number of flights from the airport had been cancelled and some of the passengers were now booked on BSX120, most of them connected at BSX’s main hub. This is cause for a further increase in the economic value of BSX120’s trajectory. This increase is immediately published by the operator. The consequences of this change are described below.
Note: In fact there may be other mechanisms in the real system through which an aircraft operator can request special handling, however those are not the subject to this scenario.
ATC planning
The arrival management service at the airport had originally set up the approach sequence taking the runway availability and traffic into account and this resulted in the 20 minute landing delay of BSX119 (the incoming flight of BSX120). The economic value of the trajectory at that time was already tagged as high in view of the value allocated to the return leg of the trajectory, but it was not yet over the predefined threshold which would have triggered collaborative action to reconsider its position in the landing sequence.
When the aircraft operator increased the economic value, the Aircraft Queue and Surface Movement Management Service (AQSMS) noted the change and determined that the value was now appropriate to trigger action. Since the time available for action was also within the predetermined limits, AQSMS interpreted the value increase as a request for improvement the aim of which was to reduce the 20 minute delay if at all possible. This activity is governed by strict rules agreed beforehand. Safeguards against abuse are in place, changes cannot unduly penalise other operators and changes can only be actually implemented if ATC agrees.
Sequence Change – Possible Alternative 1
As a first step, AQSMS requests a new approach sequence, taking BSX119 and other possible requests into account. The results are then proposed to the operators of the affected aircraft in the form of new constraints. If they agree, ATC is given the new proposed sequence and it is implemented if possible. Aircraft operators can follow the developments on line through the changes to the trajectories. This alternative is a possible precursor to the SESAR UDPP. It differs mainly in that the ATM network offers a change of sequence rather than aircraft operators generating the necessary changes. However, in this CDM time-frame it may be more realistic to follow this alternative until aircraft operators organise themselves to run a proper User Defined Prioritisation Process (UDPP) service.
Sequence Change – Possible Alternative 2
AQSMS alerts the aircraft operators concerned that collaborative action is required to resolve the situation. Since all partners are using the same “picture” of the ATM network, using applications with similar functions, they can quickly evaluate the impact of the request(s) on their operation and agree the changes needed to the trajectories. The proposed changes are then published for the planning application (e.g. AMAN) which generates the new constraints. This alternative is in line with the SESAR proposed UDPP service. It is not certain that it can be widely implemented in the short-term; however, local instances of this type of working may in fact be found feasible.
Through the actions described in Alternative 1 above, BSX119 is given a trajectory modification which results in a landing delay that is only 15 minutes.
Passenger progress from arrival at the airport to the passenger screening area
On arrival at the airport, Mr. Mariani’s taxi was met with a long queue of vehicles at the curb. This added a further few minutes to his already delayed arrival.
Since he had checked in at home, he proceeded directly to the baggage drop-off point of BSX. This facility is shared by several airlines and as forecasted, there was a queue of passengers waiting to deposit their bags.
When it was his turn, Mr. Mariani was asked to scan his boarding pass then he handed over his single suitcase, took possession of the baggage tag and was then ready to proceed towards the boarding gate.
The airport is running an extensive Timely Passenger Delivery Service (TPDS) to which BSX has subscribed. The company providing TPDS on behalf of the airport has established several Control Over Passenger Behavior Points (COPBP) along the passenger flow. These points are used to determine the best and most cost-effective method of influencing passenger behavior in a way that is experienced by the passengers as un-intrusive but which nevertheless ensure a highly successful TPDS. The exact location of these points is customized to fit each airport.
Check in at this airport or baggage drop-off is COPBP0 following which control is seen as “limited”.
TPDS noted Mr. Mariani’s passage of COPBP0 and in view of his delayed arrival a warning was displayed on the scanner’s terminal politely asking him to proceed to Passenger Screening without delay. Had the boarding pass been printed at the airport, the warning would appear also on the printed document. As a general rule, whichever new check-in method is used (e.g. boarding pass on a PDA or smart phone) the warnings and requests are sent/displayed in the most appropriate manner. If Mr. Mariani had no baggage to drop off, his presence would not have been recorded until he reached COPBP1.
Passenger progress tracking – Possible Alternative 1
The passive method entails having the passenger scan the boarding pass at predetermined points along the path to the boarding gate. This alternative requires additional scanning equipment and communications into the net-centric environment and may cause delays if congestion occurs. It is essential that passengers do scan at all the required points as otherwise the uncertainties in the TPDS would become too big.
Passenger progress tracking – Possible Alternative 2
The active method is using Radio Frequency Identification (RFID) technology. The RFID chip, in the form of a stick-on is issued and activated the first time the passenger scans the boarding pass printed at home or when the boarding pass is issued at the airport. Sensors located at the required points along the passenger flow pick up the signals from the chip which contain a code that is unique to the airport, the flight on the given day and the passenger. Introducing a culture where passengers need to ensure that the stick-on chip is placed on the boarding document (or some other suitable location if there is no paper boarding document) can be a challenge but is probably not a showstopper. However, issues concerning personal data protection must be addressed properly.
At this airport, the passive passenger tracking method is in use. COPBP1 is collocated with the passenger check point just before the Passenger Screening facility in the Schengen area of the terminal. TPDS notes Mr. Mariani’s passage into the security area. He was now in an area that carried a passenger behaviour control tag of “extensive”. This meant that there were now several options for reaching individual passengers if it was necessary to motivate their faster progress towards the gate.
PFIS monitors the length of the Passenger Screening queue. If it reaches certain predetermined lengths, warnings are published to which the organisation providing the Passenger Screening service needs to react by implementing agreed scenarios aimed at reducing the queue. If the Passenger Screening queue warning status remains in effect longer than a pre-set limit, the airspace user applications also react with advice to the operators on possible mitigating measures.
Aircraft turn-round
BSX119 arrives at the gate and the trajectory becomes idle in the spatial sense while it evolves in the time dimension. In the 5th dimension, its economic value, it already carried a high classification because of the value allocated to the next section of the trajectory which will be flight BSX120. There is a theoretical point alongside the turn-round time axis when the idling trajectory changes from being BSX119 to BSX120. Even in this idle state the trajectory is consuming resources and it can change in the time dimension as well as the economic dimension. Even the spatial dimension continues to exist in a virtual sense, affecting short term planning and providing turn-round progress information to the network as required.
In the case of BSX120, the economic dimension cannot go any higher but the time dimension is being looked at by the aircraft operator to determine the measures needed to ensure a timely arrival back at the hub in order to allow connecting passengers to transfer properly. The options are being considered taking the complete network operation of the airline into account.
It is determined that by ensuring a very tight operation, it should be possible to turn the aircraft round in the available time and hence no change to the trajectory is needed. This confirmation is published and TPDS notes the reduced time available for aircraft turn-round. TPDS assumes that in actual practice this shortened time is likely to result in a small delay and hence it is even more important to have all passengers at the gate on a timely basis. TPDS therefore implements a scenario specifically developed to increase effectiveness in such circumstances.
Passenger progress from passenger screening through the shopping area
Having cleared the Passenger Screening check, Mr. Mariani is now in the renowned shopping plaza of the airport. He did check the gate of his flight on one of the monitors as he left the Passenger Screening facility and saw that the monitor advised passengers to proceed to the gate but he decided to do some shopping first and may be even have refreshment before walking to the gate. In other words, Mr. Mariani was exhibiting the desired passenger behaviour for which the shopping plaza had been built for in the first place and he was also exhibiting the expected human response to a generic message (“go to the gate”) which he had seen many times and which no longer conveyed the intended urgency. This was happening even after the rather longish trip to the airport. Basically, here was another potentially late passenger in a situation that TPDS was designed to resolve.
When TPDS was introduced at the airport, each concession (shops as well as restaurants) was equipped with an entrance boarding pass scanner/display and passengers were asked to scan their boarding passes when entering. TPDS recognizes those passengers who are in danger of being late arriving at the boarding gate and the display presents a friendly warning addressed to the passenger containing also useful information about how long it will take for them to reach the gate from the particular establishment. A similar warning is generated when checking out from shops.
The check given by the cashier in shops and the waiter/cashier in restaurants may be accompanied by a printed note, containing the warning and
information as a direct reminder to passengers to hurry to the boarding gate. TPDS can be programmed to even prevent access to the concessions in extreme cases.
The entry points to the concessions are also COPBPs and beyond them the concession area is considered as of very tight control. There are dedicated displays that list time critical flights and possibly passenger names as well as dedicated PR announcements heard only in the given area, again possibly with passenger names, to urge the affected passengers on.
When Mr. Mariani scans his boarding pass, he notices the warning on the display and decides to expedite his shopping. While inside the store, his name is called twice by the automated system of TPDS. He decides to forget about the beer and proceeds directly to the gate.
Collaborative planning of BSX120’s departure
The captain of BSX120 confirms that it will be necessary to deice the aircraft before take-off. Using his EFB, the captain communicates with the dispatcher assigned to his flight, who notes the de-icing request and adjusts the ground portion of the trajectory to include a pass through the remote de-icing pad.
The change is published by the aircraft operator and all applications that are subscribers to the trajectory note the change and perform any necessary evaluation of the impact of the change.
It is determined by the CDM Milestones Application that an on-time take-off (as determined with a view to achieving an on time arrival) is still possible. The CDM message exchange with the CFMU takes place as usual.
The Baggage Flow Information Service (BFIS) reports that the required 100 % screening of passenger baggage for flight BSX120 has been completed and the baggage is delivered to the aircraft.
The Hold Cargo Information Service (HCFIS) reports that a container of urgent merchandise has not been delivered yet and hence will not be available for loading if the scheduled departure time is not modified. In view of the very high value trajectory and other considerations (e.g. the availability of alternative transport means) the dispatcher decides not to modify the trajectory and the particular cargo item is de-coupled from BSX120.
The Departure Management service (DMAN) has in the meantime included BSX120 in the sequence for the runway that is expected to be used for take-off. CDM’s Variable Taxi Time module has calculated the expected taxi time taking into account the de-icing process as well as the taxiway surface conditions, both of which act in the direction of longer taxi times. AQSMS is aware of the calculated take-off time as well as the very high value attached to BSX120’s trajectory, however, the calculated take-off time is still well within the limits and hence no specific action is taken. CDM’s pre-departure sequence application is also allowed to work without intervention. Had the calculated take-off time been outside the limits, AQSMS would have triggered the local collaborative process which aims to achieve agreed improvements in such cases.
Since several warnings from different services were affecting the trajectory of BSX120, it was put in an alert status by the end-user planning application of the airport operator. Their gate planning could be affected by a delayed push-back. This alert status was cancelled when CDM reported that the necessary milestones were being met.
BSX120 pushes back on time.
The actual taxi sequence is published by CDM and the de-icing company uses this information to correctly position its equipment at the de-icing pad to be able to handle the different aircraft types in the most efficient way possible.
BSX120 lifts off within 20 seconds of the calculated time.
Performance evaluation
When BSX120’s lift-off time is published, the Performance Evaluation Service (PESE) records all information it requires to generate the
performance data set for this trajectory. If data is missing, it attempts to acquire it automatically and failing that, it triggers a request at the partner designated to run the performance related activities. In this case it is the airport operator who receives such requests for manual intervention. Once the data set for the trajectory is complete, it is published as yet another available for use by the performance evaluator end-user applications. These applications enable the various partners to evaluate (using agreed and standardised metrics) their performance in the handling of individual trajectories as well as the overall performance of the operation. This activity forms a part of the collaboration agreement between the partners and is used for improving CDM performance on both the local and the network level.
Note: Like parts of the article, parts of this scenario have originally appeared in the L4CDM study for EUROCONTROL.