For many European airports, the environmental aspect in their activities plays an important role. Various aviation stakeholders consider the environment as one of the key performance areas for their operations. In addition, the national authorities have imposed stringent environmental regulations to protect citizens living near airports and therefore the aviation stakeholders must innovate in order to grow within given constraints.
Innovations in air transport can be categorised in aeronautics (directly related to the aircraft, such as airframe structures, aerodynamics and engines) and air traffic management (ATM). The latter is comprised of advanced (operational) concepts and/or enabling technologies in the fields of communications, navigations and surveillance (often referred to as CNS) to safely manage air traffic flows efficiently in terms of time, costs and environmental aspects.
Environmentally Responsible Air Transport (ERAT) is a research project that addressed the Air Traffic Management (ATM) community's need to reduce the environmental impact per flight to allow for sustainable growth.
The objective of project ERAT was to develop and validate Concept of Operations (CONOPS) for the extended terminal airspace of a medium and a high density traffic airport, in such a way that the environmental impact of air traffic in 2015 should be significantly reduced while maintaining safety levels and airport and airspace capacity. The concepts were directly related to the concept work from SESAR members in ERAT, which they would undertake in the SESAR work programme.
Project ERAT focused on more efficient and environmentally friendly operations in the extended terminal airspace by facilitating more Continuous Descent Approaches (CDA) and Continuous Climb Departures (CCD).
The validation activities focused on the effects on the environment, safety, capacity and human factors. For both concepts, real-time simulation exercises were planned and performed to assess the aforementioned benefits and impacts. The objective of the validation plans was to bring it as close to the target operational environment as possible, supporting the ultimate goal to deploy the concept of operations.
The ERAT project aimed to identify operational initiatives, develop concept elements, integrate them and validate a concept of operations that reduced the environmental impact of air transport operation in all phases of flight in the (extended) terminal area.
At very high level, the phases required to undertake the development of an operational concept for air traffic management could be summarised as:
- Inventory of concept elements
- Define validation plan
- Define Concept of Operations (CONOPS)
- Summarise findings
The ERAT consortium has worked out these phases towards following stepwise approach:
- Identifying operational initiatives and develop concept elements with the potential to reduce the environmental impact.
- Selecting the operational concept elements to be included in the CONOPSs.
- Embedding those concept elements within CONOPSs for the terminal airspace of two airports (one with medium density and one with high density traffic, respectively Arlanda and Heathrow airport) based on the SESAR CONOPS.
- Develop a validation strategy and validation plans for the concepts at both airports.
- Undertake validation activities of the CONOPSs (e.g. with Real Time Simulation sessions).
- Assess quantified benefits of the concept of operations in terms of environmental impact, safety and capacity.
- Continue with validation and verification activities focused on preparing for live trials and deployment orientation.
It was decided at the beginning of the project that Stockholm Arlanda and London Heathrow were the centre points of the developed concepts - Arlanda (ARN) being representative as a medium traffic density airport and Heathrow (LHR) being representative for a high traffic density airport.
The important elements of the Concept for Arlanda included:
- Arrival Manager (AMAN) development;
- Controlled Time of Arrival (CTA) point and accuracy;
- Development of a Human Machine Interface (HMI) to better support controllers;
- Parallel routes;
- Procedure for short-haul traffic.
The ERAT Concepts of Operations for London Heathrow aimed to deliver benefits to both arrival and departure traffic into and out of London Heathrow. The latest concept was the innovative ERAT LHR concept, based on:
- High level airborne holding;
- Precision navigation approach transit
Overall, LFV (Luftfartsverket - SW) was very satisfied with the results of the concept development and validation work undertaken in this project. The most important conclusions are summarised below.
- Two route designs with STARs (Standard Terminal Arrival Route) have been validated with this concept. The concept proved to be able to accomplish a landing rate between 30 and 34 per hour. The arrival planning and predictability of operations were improved, allowing an increase in continuous descent operations, reaching approximately 80% up to 100% of all traffic. The current day operations proved to be very efficient due to short vectoring by air traffic controllers.
- The fuel burn results for the P-RNAV (Precision Area Navigation ) STARs were comparable to the baseline situation, however the track miles were approximately 10 NM longer. When the RNP (Required Navigation Performance) STARs were used, the track miles were comparable to the current day operations and approximately 3% fuel burn and CO2 reduction for arrivals was achieved. The short flights (less than 30 minutes) were now included in the arrival planning and could absorb delays on the ground rather than in the air. This allows for potentially further fuel burn reductions.
- The fixed arrival route structure caused less lateral flight track dispersion which subsequently reduced the noise exposure on the ground locally. The noise footprint areas were reduced up to approximately 20% when compared to the current day situation.
- The concept had no influence on Continuous Climb Departure (CCD) which was quite often allowed in the current day operations. The controllers judged that the current safety levels were also maintained. The simulations have demonstrated feasible advanced AMAN functions with associated HMI to run time based operations. A further concept refinement and other remaining issues will be addressed in those SESAR projects which follow-up on the ERAT achieved results.
Although the results may not be so promising, NATS (National Air Traffic Services, UK) was satisfied to have been able to perform this second concept development cycle to further develop the initial concept. Therefore these conclusions only address this second cycle as they form input for follow-up development cycles.
- By using FTS (Fast-Time Simulation) the cost of the project could be minimised while several design options could be explored before initiating a RTS that usually comes at higher cos
Much of the achieved results were exchanged and/or transferred from ERAT project team members to others working directly for SESAR projects, particularly when for the same organisation which was often a SESAR member.
The ERAT consortium recommended the following to SESAR:
- To take an example of concept development and validation work undertaken for Stockholm Arlanda terminal airspace. The ARN concept provides a good showcase of Time Based Operations for SESAR, with system support on the ground.
- To learn from airspace and route design work undertaken for London Heathrow in SESAR work dealing with high traffic density terminal airspace. The development cycles have revealed some very useful concept elements (e.g. point merge) and route design considerations in a complex airspace.