Idea 4: Continuous descent

Proposed action

Increased use of Continuous Descent Operations (CDO) and reduced use of the downwind for quieter aircraft arrivals.

Implemented - February 28, 2019

As part of the follow up process under the Airspace Change Communications and Consultation Protocol, NAV CANADA will complete a post-implementation community impact assessment. This will be initiated approximately six months following implementation. 

Six Ideas consultation results are available as part of the Quieter Operations Roadmap - Public Engagement Report

Reasons for increased CDO

In busy airspace such as that surrounding Toronto Pearson, keeping flights flying at the same altitude can be necessary to safely manage traffic flows. In order to keep aircraft at a level altitude, pilots must increase thrust and drag, which can create more noise. Increasing the use of Continuous Descent Operations will enable more aircraft to operate in a quieter flight profile. In some cases, the proposal will have the added benefit of allowing the aircraft to use "short cuts" to final approach that may reduce use of the downwind portion of the existing flight path.

How CDO works

NAV CANADA will leverage satellite-based navigation technology, known as Area Navigation (RNAV), to design new transitions to the final approach that provide for continuous descent. RNAV allows aircraft to fly a defined route using station referenced navigational aides (usually satellites) or on-board navigational equipment or both.

When CDO would be used

Continuous Descent Operations can be used during daytime and evening periods when traffic is relatively light. Usage will depend on capacity demands and tactical sequencing requirements – not all traffic will be cleared to use these approaches. During busy traffic periods, operations at Toronto Pearson require use of a high-low procedure to ensure safe separation between aircraft, so use of CDO would not be possible. The approaches for runways 15 and 33 can also be used as night-time approaches, as the base leg portion of the approaches are already outside the boundaries of the city.

The benefits

Continuous descent approaches are the quietest type of approach, offering noise reductions between 1 and 5 dBA depending on the phase of flight. A reduced noise footprint from continuous descent results in fewer households flown over at noise levels above 60 dBA.The estimated reduction in population impacted at specific noise levels for composite approaches to each runway, assuming the usage of common downwind and base legs, is as follows:

Runway 23

  • Reduction in population overflown at greater than 60 dba (depending on the transition): 5 to 8%
  • Approximate population reduction for all approaches to the runway: 22,000

Runway 24 L/R

  • Reduction in population overflown at greater than 60 dba (depending on the transition): 10 to 14%
  • Approximate population reduction for all approaches to the runway: 80,000

Runway 05

  • Reduction in population overflown at greater than 60 dba (depending on the transition): 1 to 7%
  • Approximate population reduction for all approaches to the runway: 7,000

Runway 06 L/R

  • Reduction in population overflown at greater than 60 dba (depending on the transition): 6 to 13%
  • Approximate population reduction for all approaches to the runway: 27,000

Runway 15 R

  • Reduction in population overflown at greater than 60 dba (depending on the transition): 2 to 12%
  • Approximate population reduction for all approaches to the runway: 27,500

Runway 15 L

  • Reduction in population overflown at greater than 60 dba (depending on the transition): 7%
  • Approximate population reduction for all approaches to the runway: 27,800

Runway 33 R

  • Reduction in population overflown at greater than 60 dba (depending on the transition): 4 to 30%
  • Approximate population reduction for all approaches to the runway: 29,800

Runway 33 L

  • Reduction in population overflown at greater than 60 dba (depending on the transition): 8 to 30%
  • Approximate population reduction for all approaches to the runway: 30,300

In addition to reducing the noise footprint for some aircraft, the new RNAV transitions will make it easier for air traffic controllers to enable "short cuts" to final approach that reduce use of the downwind portion of the existing flight path during quiet traffic periods.

The impact

Some communities under the base leg portion of the flight path may experience increased regularity of aircraft passing overhead. As this type of approach will allow more aircraft to "short cut" to final approach, areas under the downwind may experience less traffic while other areas may experience more. Specific impacts will depend on where you live.

The maps below show composites of the approaches to each runway and associated  noise modeling (more on noise modeling below). The altitudes shown on the maps for this initiative are approximate – based on a 3 degree angle of descent – and will vary depending on air traffic sequencing and management requirements and the manner of operation by pilots. We have also included samples of current flight paths and associated noise models.

If you live:

  • West of the airport, you’ll be interested in maps related to Runways 05 and 06L/R
  • East of the airport, check Runways 23 and 24L/R
  • North of the airport, check Runways 15L/R
  • South of the airport, check Runways 33L/R

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