GTD Develops Breakthrough Technology for Future Continuous Descent Approach (CDA) in Air Traffic Control

CDA is a more efficient landing procedure that enables aircraft to descend smoothly from cruising altitude to the runway without the traditional “stepped” descent pattern.

From Stepped Descent to Continuous Descent

Traditionally, landing aircraft approach a runway by descending in steps from cruising level to ground level. At each step, pilots must adjust engine thrust to level out the aircraft before descending again.

This conventional method:

• Increases fuel consumption
• Generates additional noise
• Produces higher CO₂ emissions

In contrast, Continuous Descent Approach (CDA) enables a smooth, uninterrupted descent (green path), reducing the need for thrust adjustments.

Airlines estimate that each CDA operation can save approximately:

• 150 kg of jet fuel
• Around 500 kg of CO₂ emissions

These environmental and economic benefits make CDA a key element of future sustainable aviation strategies.

The Operational Challenge: Airspace Capacity

Despite its advantages, CDA presents operational challenges. One major drawback is the potential reduction in airport or Terminal Manoeuvring Area (TMA) capacity.

Maintaining vertical separation between aircraft during continuous descent requires more complex air traffic control (ATC) strategies. To manage traffic flow safely, ATC may issue specific time constraints for aircraft to meet designated waypoints, such as:

• TMA entry
• Initial Approach Fix (IAF)
• Final Approach Fix (FAF)

These time requirements significantly increase the complexity of calculating optimal descent trajectories — particularly when fuel efficiency and emissions reduction are also objectives.

GTD’s Onboard Fast Optimiser for CDA

To address this challenge, GTD has developed an onboard fast optimiser for Continuous Descent Approach operations.

The system:

• Calculates descent profiles that minimize engine thrust usage
• Reduces reliance on speed brakes
• Ensures compliance with ATC time constraints

The optimiser continuously monitors the aircraft’s actual trajectory. Whenever the deviation from the intended path exceeds a defined error threshold, the system automatically launches a new optimisation process and re-plans an optimal descent profile in real time.

This dynamic re-optimisation capability ensures both:

• Operational efficiency
• Air traffic safety compliance

Supporting Sustainable and Intelligent Aviation

By combining trajectory optimisation, fuel efficiency and ATC constraint management, GTD’s technology contributes to:

• Lower fuel consumption
• Reduced CO₂ emissions
• Decreased aircraft noise
• Improved environmental sustainability

The development positions GTD at the forefront of advanced air traffic management and sustainable aviation technologies, supporting the transition toward smarter, greener flight operations.

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