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Study of optimisation procedures for decreasing the impact of noise around airports II

Deliverables

Arrival Procedures in TAAM are defined geometrically as a succession of waypoints or special points called NoName Stars, from the STAR fix to the runway threshold. In those points the user can set altitude restrictions, IAS restrictions or DME restrictions. Once the procedure is geometrically defined in TAAM, the tool randomises automatically aircraft performances to adapt the trajectory for each aircraft to the ideal profile represented by the geometric procedure. When the procedures are defined in terms of thrust or configuration setting, additional pre-processing work is required to model them in TAAM since the tool does not consider these parameters. In this case, it is needed that the procedures are translated into parameters understandable by TAAM (rate of climb and descent, climb speed etc, specified in Level Bands). When the procedures are defined in terms of geometry and speed, they can be modelled in TAAM with a degree of realism that depends on the specific procedure and on the intrinsic limitations of the tool. The first limitation is related to the relative distance between successive Star points: two consecutive STAR points must be at least 0,5 NM far between them. If one of the new procedures contains significant speed changes or altitude changes in less than 0,5 NM (as it occurs), we should make assumptions to simulate that stage of the procedure. There is also another limitation regarding the minimum distance between two consecutive and ordinary waypoints; they must be at least at 3 NM. Other limitation is that the last point of the STAR before the runway threshold is understood by TAAM as the initial point of a final descent of 3 degrees glide slope to the runway. We should do this last point as little as TAAM lets us maintaining the definition of the procedure. Once the user has set the altitude and speed restrictions in each waypoint of the star, aircraft will comply them if the aircraft characteristic file (performance data) contains within its limits the necessary rate of descent, descent IAS, etc to reach those values. In order to make aircraft comply with these restrictions, the user must modify and adapt, for each procedure, the parameters related with the descent of the aircraft: descent IAS, rate of descent, speed on final, and so on. This means that for each real aircraft model, there will be in the simulation as many models as different procedures are going to be analysed. Descent IAS and rate of descent are specified in Level Bands, where the value is the upper limit of the Band, specified as a Flight Level. The maximum number of Level Bands for each stage of flight is 20. If the user want to include in the scenario a very detailed procedure, he must increase the number of level bands in order to describe all the altitude, speed, and rate of descent changes performed by the aircraft flying the procedure. Although the aircraft complies with the altitudes and speed restrictions included in the definition of the procedures, this does not mean that the aircraft performs a correct profile. Once the aircraft passes through a waypoint at the required altitude and speed, TAAM establishes a pseudo-cruise phase that can last even more than a minute. So the descent is stepped and not continuous. Making a fine-tuning of the performances we can reduce this cruise phases and obtain a realistic profile. The main risk we assume is that modifying the aircraft performance data and establishing so many altitude and speed restrictions can make the model not flexible enough to sequence properly the arrival flow to the airport. One of the most important objectives of the pre-calibration tests is to determine whether or not the TAAM output is realistic.
1.Pilot and controller tools 1.1. Flight Deck displays In support of the Sourdine procedures, the following items are added on the flight deck: - Vertical navigation display - Flap deployment cues See [D6-2] for more details on the navigation displays. Further modifications are assumed not to be required. The relevant procedure is assumed to be available in the navigation database. Which is for the experiment the case. Pilot feedback on Flap/gear deployment cues - The use of cues for the selection of Flaps 1 and Flaps 2 is helpful; the cues for gear down, Flaps 3 and Flaps full cause too much clutter on the display. These three points are located too close together and below 2000 ft, they are not very useful. Common practice to lower gear at 2000 ft is used. - The speed is sometimes too high to select the flaps at the indicated position (which may result in disregard of these points). In case of overspeed, the flaps/gear selection advisory should be adjusted so that the advise does not result in overstressing the aircraft. - The flap and gear deployment cues have to be optimised according to the prevailing wind conditions, otherwise, the predictions are incorrect. Furthermore, finetuning is needed for the exact location of the cues on the profile (e.g. putting the points somewhat later could optimise noise and fuel burn). - The cues for Flaps 3, Flaps full and gear down result in too much clutter. - The influence of wind conditions should be taken into consideration. A more dynamic tool (that is maybe adaptive) is desired, for example, the possibility of pilot input to customise the approach. - It is suggested to keep the deployment cues in view after the aircraft has passed them. In the present setup, the indications disappear as soon as the aircraft has passed them. The clues are then removed, but they may still be needed in case the selections have not yet been made. 1.2. Ground tools Controllers will be provided with two tools when working with the Sourdine procedures. These are Ghosting and monitoring aids. Ghosting A ghosting tool projects the position of an aircraft onto another plane. For the Sourdine II prototyping sessions, the inbound aircraft from the SUGOL IAF are projected onto the RIVER arrival route. This provides the controller with information about the relative positions of the aircraft on the two inbound routes, prior to merging into a single stream. The current version of the tool uses a basic ghosting algorithm that determines the distance to go (along track) to a projection-point on the route. This distance is then backtracked across a given path in order to determine the location of the ghost plot. This path can either be a straight line or a predefined route (e.g., RIVER arrival route). For the projection point the NARSI position was configured, as all arrivals will have to be merged at this location, even those aircraft that were cleared to proceed direct from SUGOL to NARSI, skipping the MICOL merging point. Monitoring aids Monitoring aids compare the current flight data with the system trajectory and detects any deviations from the cleared flight level or the cleared lat/lon route. In case, a deviation of the flight from the system trajectory is detected, a non-conformance warning (NCW) is issued. These NCWs are displayed in line 0 of the label and have the following meaning: - FL DEV means that a deviation from the cleared flight level has been detected, - FL Bust means that the cleared flight level has been busted, - LAT DEV means that the deviation from the cleared route has been detected. Controller feedback on Ghosting tool - Ghosting was experienced as very helpful. - It facilitates the merging of inbound streams from RIVER and SUGOL, which is done by the FDR/DCO. - Participants considered whether it would be advantageous to display the ghost plot on the basis of time rather than distance (as it is currently done). - If ghosting was based on time, the information could also be provided to ACC. Controller feedback on Monitoring Aids - Participants appreciated the general idea of providing monitoring aids to the controller. Nevertheless, they were not fully satisfied with the chosen implementation. - First, it was noted that FL deviations were only detected in case the aircraft descended without being cleared for the CDA (i.e., the CDA was not entered in the label). In contrast, there was no FL deviation, if the aircraft was cleared for a CDA, but did not initiate it in time. - Secondly, it was maintained that if the ARR and FDR/DCO s tasks primarily consist in monitoring, then there be a broader set of monitoring alerts. For instance, controllers could be warned in case of insufficient separation between a heavy and the subsequent aircraft.
Procedure design process: The project started with the generation of an overview of current practices and future technology related to the environmental friendly approach and departure procedures. Based on those results and after feedback from an international expert panel a first set of potential procedures was developed. Those procedures were assessed using single event simulations (SES) with Airbus aircraft performance and noise calculation tools. Aircraft included in the study are the short/medium-range twinjet A320-200 and the long-range, four-engines A340-300. The performance studies involved computation of operational trajectories based on the procedure descriptions. These studies enable a first selection of the initial procedures based on aircraft performance limitations and provide trajectories that reflect performance characteristics and limitations of the aircraft. The trajectories are used as input for single event noise prediction carried out with Airbus Noise Level Calculation Program (NLCP). This assessment led to the selection process where 5 approach and 3 departure procedures were selected to be further assessed in detail during the project. Description of the 8 Operational flight procedures (including two baselines): Brief description of Approach procedures: - Procedure I: Baseline FMS approach procedure: This procedure has a standard vertical flight path, with a level segment at 3000ft, during this last part of the flight path deceleration is performed, making this procedure quite competitive and better than standard approach procedures. - Procedure II: Basic CDA with 2º initial FPA: this procedure follows a fixed 2-degrees path angle from 7000ft up to ILS intercept at 3000ft.The aircraft decelerates at idle thrust in clean configuration during this part of the flight, deploying the cleanest possible landing configuration on landing. - Procedure III: Basic CDA with 2º initial FPA and increased final glideslope: the difference between procedure II and procedure III is the steeper flight path angle (4º instead of 3º for all other approach procedures) on the ILS. - Procedure IV: CDA with constant speed, variable FPA segment at landing configuration: the procedure is largely flown, from 7000ft to ILS intercept, with idle thrust and in landing configuration. - Procedure V: CDA with constant speed, variable FPA segment at intermediate configuration: the procedure is similar to procedure nº IV, with the difference that the variable FP is the result of an idle thrust descent from 7000ft to ILS intercept on an intermediate configuration. Brief description of Departure Procedures - Procedure 1: Baseline take-off procedure: this is the baseline departure procedure (NAP ICAO-A) - Procedure 2: Sourdine optimised close-in: this is the closein departure procedure, for which the noise relief is located relatively close to the runway. The procedure is distinguished by a deep cutback in thrust, followed by a gradual increase in thrust starting at 3000ft [D3-1-2]. - Procedure 3: Sourdine optimised distant: this is the distant departure procedure, same as for the previous one with the difference that the noise relief is further away from the runway. Again the procedure is distinguished by a deep cutback in thrust but on reaching zero flap speed (Vzf), followed by a gradual thrust increase starting at 5000ft [D3-1-2].
Show WHEN, HOW and WHERE to implement the Sourdine II procedures; The Sourdine II departure procedures are found to be currently implementable, while the arrivals should follow a stepped implementation (improvement cycle) as follows: WHEN? When valued by decision maker after local assessment processes. How? Through 4 STEPS (the last defines the cycle for more improvement) STEP 1 implementation, with the current situation, will take full advantage of existing technology. STEP 2 , the less intrusive procedures can be implemented in the short-term in a busy traffic ATM system. STEP 3 the more intrusive procedures can be implemented in the short term in low density traffic. Where? The Sourdine II Arrival procedures currently in Step 1 (of the implementation cycle) - Procedure II can be implemented in large airports - Procedure V in medium airports - Procedure III in small airports Procedure IV should be further assessed for maintenance evaluation, feasibility and acceptance by the users.Jump to STEP2 should be introduced in high density traffic once the challenges to define operational procedures that can be used by flight crew with no significant change in workload are solved and ways are found among all as to maintain minimum separation between aircraft resulting in keeping the airports’ safety and capacity level.
HOW are the various assessments done? The validation methdology applied in the SOURDINE-II project has been described in the deliverable D2-1: Validation Methdology. It is based on the MAEVA Validation Methodology. The assessments are part of the overall validation work. The newly defined Noise Abatement Procedures have been assessed with respect to Noise, Capacity, Safety and Acceptance by the Pilot and the Air-Traffic Controller. For the execution of these specific assessments, various computer models, tools and simulators have been used. The specific methods applied in these assessments have been described in detail in the following reports: Noise: D5-1, D5-2 Capacity: D4-1-1a Safety: D4-2-1 User acceptance: D6-1, D6-2, D6-3, D6-4, D6-5. SUMMARY of the results of the assessments NOISE: All Sourdine II procedures provide significant noise reduction as compared with current day practice. Approach: With single event simulations, it has been demonstrated that the SOURDINE II reference approach procedure, as compared with current practice, shows benefits more than 5dBA in a very large range of the procedure (see chapter 4). As compared with the reference, even more noise reduction can be achieved, especially with procedure III and IV. Procedure III providing noise relief at all noise levels; procedure IV mainly at the lower (~55 Lden) noise levels. A population impact study was performed at Madrid-Barajas airport and all four approach procedures showed reductions in impacted population. Procedure III was responsible for the largest change in impacted population. However, procedure IV, and to a lesser extent procedure II produced noticeable reductions in numbers under the 60dB Lnight contour. CAPACITY: Application of the SOURDINE II approach procedures will lead to a reduction of the peak hour capacity. Obviously, this is especially the case for procedure IV, where a long distance is flown at low speed (FAS). However, for procedure II, III and V, relatively small reductions in peak hour capacity occur. This capacity reduction only presents a problem during operations where demand exceeds the capacity. In off-peak hours or in the situation where traffic is scheduled more regularly over the day, no sustained capacity problem would occur at the four airports considered in this analysis when procedure II, III, or V would be implemented. This is even true at 2015 traffic volumes. It is assumed that implementation of the departure procedures will have no capacity impact. SAFETY: The combination of parallel runways with CDA procedures is an identified safety issue. This operation is not in line with the current ICAO guidelines for parallel approaches, i.e., 1000ft vertical separation is required until aircraft on both approaches are locked on the ILS Localiser signal. Possible solutions on this subject that need further exploration are for example the use of curved approaches based on approach procedure with vertical guidance (APV procedure) or to have a short level segment for one of the runways. Also the approach with the optimised level segment (SII reference) may be an option here. During the expert panels and the final meeting various experts emphasised the importance to have a generic noise abatement procedure and no tailor made procedures for each airport. This recommendation is mainly derived from a safety point of view, increased risk on pilot error when flying many different procedures. ACCEPTANCE OF PILOTS AND CONTOLLERS: The pilots and air traffic controllers were positive on procedure II and II-A (variation of procedure II including speed constraints). Procedure II-A basically leads to more time between the various configuration changes and therefore makes it more controllable for the pilot. Speed constraints have the risk however of leading to a negative noise impact as compared with a more noise-ideal procedure II. It was suggested by some of the controllers to extend the prototyped version of the ATC monitoring aid with an alert when the separation minima are violated and the controller needs to intervene.

Exploitable results

With the continuing growth of air traffic as well as the ever increasing level of urbanisation around most airports in Western Europe, the impact of aircraft noise and emissions on the quality of life for the surrounding communities has become a serious issue to be dealt with. Many European airports already face the conflicting problems of increasing their airport capacity to meet the amount of traffic, and the increasing pressure from the general public to reduce environmental impact, particularly noise and emissions, of the increased traffic volume. Many efforts are already being undertaken to reduce the source noise itself by the introduction of more silent aircraft and engines. On the other hand, a further solution to noise reduction around an airport is the definition of new approach and departures procedures. By modifying or optimising the operations and traffic flow of aircraft around the airport, it should be possible to achieve noise reduction. The noise assessment results show that all Sourdine II procedures provide significant noise reduction as compared with current day practice. With single event simulations, it has been demonstrated that the SOURDINE II reference approach procedure shows benefits more than 5dBA in a very large range of the procedure. From all approach procedures Sourdine II arrival procedure III, featuring an increased final glide path angle, provides the largest noise benefit compared to the reference procedure. The optimized departure procedures featuring optimized thrust management provide noise reduction in the targeted zones compared to current PANS-OPS procedures, either close-in or at distant positions. The distribution of the fleet mix will influence the shape of the noise contours considerably (i.e. unbalanced use of runways). Noise assessment conclusions are the same (i.e. slight differences depending on fleet-mix flow) for all scenarios. Major noise benefits are mainly determined by higher altitudes for approaches while for departures on the thrust settings. It is recommended to perform flight trials in a low-density situation (e.g. at night) to get detailed feedback on aircraft performance as well as pilot and controller acceptability from hands-on experience. Results from these flight trials can support additional assessments like performed in this project to reach the ultimate goal: continuous descent approaches during peak-hour operations at major European airports while maintaining or even improving capacity and safety.

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