About

The GeoAlt project addresses several challenges with the current use of barometric altimetry:

1. Transition Layer Variability:
Transition layers exist at different heights worldwide, creating inconsistencies in flight operations.

2. Manual Input Errors:
Switching between standard and QNH altitudes requires manual input, which can introduce errors.

3. Inefficiency and Buffer Requirements:
Due to uncertainties around the transition layer, air traffic control (ATC) needs to build in substantial buffers, leading to inefficiencies.

4. Lost Flight Levels:
The existing transition layer inhibits continuous climbs and descents.

5. Environmental and Capacity Impact:
Uncertainty in vertical aircraft positions limits ATC's ability to design optimal route structures, negatively impacting the environment and airspace capacity

Research Approaches and Methodologies

1. Concept Development:
NATS: Building large fast-time simulations to model airspace design using GeoAlt and comparing it to the current barometric model.
DLR: Conducting aircraft simulations for cruise and descent phases to evaluate performance.

2. Aircraft Performance Analysis:
DLR Expertise: Analyzing individual aircraft performance and proposing the comparison of real flight data (using barometric altimetry) with simulated flight data (using GeoAlt). This involves re-simulating real flights under identical conditions but with GeoAlt.
Validation: Re-simulations will validate models against real flights, enabling the creation of a simpler fast-time simulation model to examine the cumulative effects on fuel consumption and overall efficiency over time.

3. Efficiency and Safety:
- Investigating the net fuel efficiency benefits of a fully geometric network.
- Assessing the removal of the transition layer and its impact on continuous climbs and descents.
- Evaluating the use of GeoAlt for Required Navigation Performance (RNP) arrivals to improve approach efficiency

1. Collision Risk Analysis:

NLR: Examining the potential consequences of reducing vertical separation minima to 500 feet, focusing on collision risk in en-route airspace (FL 290-600). The analysis includes establishing accuracy and integrity requirements, assuming a fully GeoAlt system without mixed airspace.

2. Wake Vortex Encounter Risk:

DLR: Focusing on the impact of reduced separation on wake turbulence. This involves detailed simulation and modeling to understand how decreased vertical separation affects the safety and efficiency of air traffic.

3. Safety and Surveillance:

Discussing the need for secondary surveillance radar and the impact of GeoAlt on ATC procedures and aircraft operations.

Considering the effects of jamming and spoofing on the GNSS systems used for GeoAlt, though this is outside the immediate project scope.

These approaches collectively aim to validate the feasibility and benefits of transitioning to geometric altimetry and reducing separation minima, thereby improving airspace efficiency and safety.

Green Route Charging (GRC)
Research Approach:
Exploratory Research: Initial feasibility studies to assess the viability of GRC solutions before considering their implementation.
Environmental Focus: Emphasis on reducing aviation's climate impact, including CO₂ and non-CO₂ emissions (e.g., contrails, NOx).

Methods:
Algorithmic Climate Change Functions (aCCFs): Use of aCCFs to identify climate hot spots based on weather forecasts, aiming to avoid areas with high climate impact.
Route Charging Mechanism Development: Investigating charging mechanisms that incentivise routes minimising climate impact, potentially offering credits or imposing premiums based on environmental impact.
Scenario Analysis: Evaluating different scenarios, such as rewarding the avoidance of climate hot spots and the implications of charging mechanisms on ANSPs and airspace users.

Modulation of Route Charges (MRC)
Research Approach:
Operational Feasibility: Assessing the practical implementation of charge modulation within the current regulatory framework.
Congestion and Emissions Reduction: Focused on reducing total emissions and traffic congestion through modulated charges.

Methods:
Traffic Data Analysis: Utilising EUROCONTROL DDR2 data from different traffic periods (e.g., February and September 2019) to develop modulation factors. Revenue Workload Ratio Preservation: Ensuring revenue neutrality for ANSPs by proportionally adjusting revenues based on route distance.
Decision Variables: Modulation of route charges (factor M) and temporal displacement of flights to optimise route efficiency.

Origin-Destination Charging combined with MRC (ODC + MRC)
Research Approach:
Integrated Charging Model: Combining ODC and MRC to create a comprehensive charging mechanism that addresses both cost efficiency and environmental impact.
Congestion Management: Introducing modulation factors on congested routes to manage sector capacity and optimise route charges.

Methods:
Great Circle Distance Charges: Implementing charges based on the shortest distance between origin and destination, irrespective of the actual route flown.
Redistribution of Charges: Distributing collected charges to overflown ANSPs based on the portion of the route flown within their airspace.
Scenario Constraints: Ensuring flights adhere to minimum cost routes while maintaining sector and airport capacity, and preserving the revenue/workload ratio for ANSPs.

These research approaches and methods are designed to explore and potentially implement solutions that can effectively reduce aviation's environmental impact while maintaining operational feasibility and economic efficiency.