Projects

Point Merge System (PMS) is an innovative technique to improve the efficiency of terminal airspace operations. It was developed by the EUROCONTROL Experimental Centre (EEC) and now constitutes a building block for medium and long term developments (as for instance 4-D trajectory management) in the context of SESAR.

The PMS operational concept is based on a specific P-RNAV route structure that is made of a point (the merge point) with pre-defined legs (the sequencing legs) equidistant from this point that should be used for path shortening or stretching. The sequence is achieved with conventional direct-to instructions to the merge point. Open-loop vectoring should only be used to recover from unexpected situations.

In 2008 EUROCONTROL identified three possible candidates for the PMS implementation, namely Oslo, Dublin and Rome. Three different projects of support to the implementation were then established with the external partner AVINOR (Norwegian ANSP), ENAV (Italian ANSP) and IAA (Irish ANSP).

“Point Merge System at Rome ACC” was the project in which ENAV was involved.

The aim of the project was to evaluate the domain suitability and user acceptability of introducing the PMS concept in Rome TMA, for the management of traffic to LIRF (Fiumicino Airport). 

ENAV Headquarter managed the project, with extensive cooperation of Rome ACC and ENAV CNS/ATM Experimental Centre. Support was provided by Eurocontrol Experimental Centre and Headquarter. Deep Blue was responsible for the organisation of the Validation activities as well as for the Human Factors assessment.

The project made up of two phases, consequential and strictly interdependent.

Phase 1 – Prototyping Sessions

The first phase focused on the design of the PMS procedures for Rome TMA and on the evaluation of their effectiveness and acceptability in Rome TMA. Possible effects of PMS on Extended TMA (E-TMA) sectors and/or on cooperation between E-TMA and TMA sectors were out of the scope of this first phase and postponed to the Phase 2.

The first phase was carried out at Rome ACC in 2008. It developed in a first stage of procedures design and in a second stage of evaluation.  The evaluation was based on four small scale prototyping sessions, in which the concept was tested in different operational scenarios depending on the runway configurations in use in both LIRF and LIRA (Ciampino airport).

An iterative and incremental validation approach was applied, which had the twofold purpose to gradually introduce the new concept to the controllers and profiting by the results of the previous session to prepare the following one.

On the basis of this approach the first prototyping session tested the concept in a simplified operational scenario marked by lack of traffic destination LIRA, application of Continuous Descend Approach (CDA) within the triangles despite radar minima constraints and lack of departures from both LIRA and LIRF. The use of a simplified operational scenario was intended to allow the controllers involved in the prototyping session to purely focus on the operational concept under investigation. A more realistic and complete operational scenario was then simulated in the following sessions, in which traffic to LIRA was added to the traffic samples and radar minima constraints within the triangles were taken into account.

Phase 2 – Real Time Simulation in the framework of TMA2010+ Project South

The second phase of the project enlarges the scope of the investigation and considers the possible impact of PMS not only on Rome TMA sectors, but also on E-TMA sectors.

During this phase a large scale real-time simulation was arranged and carried out at ENAV CNS/ATM Experimental Centre. It consisted in the first real time simulation of the TMA 2010+ Project South.

The purpose of the simulation was to assess domain suitability and user acceptability of the PMS concept in a more complete operational scenario than the one used in phase 1. The operational scenario taken into consideration included both TMA and E-TMA sectors. The traffic samples contained traffic to and from both LIRF and LIRA, as well as to and from some other minor airports situated in the Rome Flight Information Region (FIR) such as Napoli (LIRN), Pisa (LIRP), Firenze (LIRQ), Perugia (LIRZ). Also in this case PMS was applied only to the traffic destination LIRF, while the traffic to the other airports was managed in the conventional way.
In addition to PMS, Arrival Manager (AMAN) was also introduced in the second phase of the project. Although AMAN is not mandatory for the use of PMS, it was proposed as a support for the pre-sequencing managed by E-TMA sectors controllers. The evaluation of the possible interoperability between AMAN and PMS was one of the main objectives of the second phase of the project.

Results Achieved

The prototyping sessions produced in the first phase of the project produced positive results on the users’ acceptability and domain suitability of applying the PMS technique in the operational environment of Rome TMA. The large scale simulation carried out in the second phase of the project confirmed the same results, highlighting also positive outcomes about the user acceptability and domain suitability in the E-TMA. 

The controllers involved in these studies found the method comfortable, safe, accurate and easy to learn and to apply. In very short time they became familiar with it and able to apply it properly and effectively, even under high traffic load and in case of non nominal events. They considered the new technique suitable to and easy to accept in Rome TMA sectors, perceiving it as the evolution of the current method based on radar vectoring as result of the introduction of the PRNAV capability.

In their opinion the adoption of this method is likely to yield the following advantages:

• standardisation of the controllers performances, thus implying a standard high quality of the traffic management, less conditioned by personal skills and one’s own tolerance of traffic density and complexity
• improved teamwork, since the standardisation of the work allows to predict and anticipate the colleague’s behaviour, expectations and needs
• general reduction of controller cognitive workload in all TMA sectors, since the standardised way of managing the arrival traffic simplifies the work and reduces the need for problem solving, continuous monitoring and R/T communication
• general high level of job satisfaction in the controllers, since the less creativity required for the arrival traffic management is counterbalanced by evident positive results in terms of spacing and runway capacity usage.

They also highlighted some drawbacks of the PMS technique, among which the following ones are worth to be reported:

• loss of flexibility with respect to the current open loop vectors technique
• conditioned applicability in certain circumstances (i.e. bad weather conditions impairing the use of both triangles and point merges), thus entailing the need for radar vectoring to continue to be applied
• concurrent application of radar vectoring and PMS method in case of traffic not 100% PRNAV equipped
• possible impact on the controllers workload in E-TMA sectors

They tended however to accept these limits as tolerable side effects of the PMS technique. They were conscious of these drawbacks, but did not consider them as limitative as to impair the acceptability of the technique itself and/or its effectiveness. On the contrary they appreciated the possibility to continue using the method even partially or in non conventional ways in the cases in which it was instead expected not to be usable at all. The management of non nominal events (i.e. bad weather, mixed equipped traffic samples and transition from PMS to radar vectoring and vice versa) confirmed these results.

Positive results have been also achieved with respect to the incremental and iterative validation approach adopted in the project. The execution of small sessions of assessment, besides allowing to test PMS in different operational scenarios of Rome TMA, confirmed to be extremely fruitful also from the validation point of view. Each session was a means to scratch hypotheses, preliminary results and possible redesign suggestions to be further checked, implemented and/or validated in the following ones. Each report was in this respect a working document intended to compare the result of the study with the ones of the previous sessions, consolidate the results produced so far and provide recommendations and way forward for the following sessions and/or phases of the project.

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