• Understanding airport operations and terminology

    While we have tried to explain and simplify technical information where possible, there are still some aviation terms and concepts included in this material.

    Let’s talk about airport operations and terminology that will help you better understand the work we did on the Six Ideas so that you can provide us with more meaningful feedback.

    Runways

    Toronto Pearson has five runways, each of which can be used in two directions. They are numbered based on their alignment with the compass heading. For example, Runway 06L is aligned at approximately 060 degrees. If more than one runway has the same heading, they are further distinguished by Left (L) or Right (R).

    Toronto Pearson has three east/west runways:

    • 05/23
    • 06R/24L
    • 06L/24R

    And two north/south runways:

    • 15R/33L
    • 15L/33R

    Runway Configurations and Operating Modes

    Runways can be used in a mixed-mode or dedicated-mode. When a runway is used exclusively for arrivals or departures, we say it is being used in a dedicated-mode. When the same runway is used for both landings and departures at the same time, we say it is being used in a mixed-mode.

    We can use our five runways in many different configurations, some of which provide us with more capacity than others.

    • Straight or Single runway configuration is when we use just one of our five runways to support a mix of arrivals and departures.
      • For example, using only Runway 23 for both arriving and departing aircraft. In this case, we would say that we’re on a single runway configuration using Runway 23 in a mixed-mode. We can use this configuration during periods of low traffic, when a single runway can handle the capacity.
       
    • Land 1/depart 1 configuration is when one runway is used for arrivals, and the other for departures. In this case, each runway is being used in a dedicated-mode.
      • For example, using Runway 33R for arrivals and Runway 33L for departures.
      • At times, to accommodate traffic the dedicated departure runway can also be used for arrivals when there are gaps in departure traffic. We call these offloads.
       
    • Dual runway configuration is when two parallel runways are used simultaneously and independently with both runways being used in a mixed-mode.
      • At Toronto Pearson, this can be done by using Runway 05/23 and 06L/24R or 05/23 and 06R/24L. Runways 06L/24R and 06R/24L cannot be used for a dual configuration because of their proximity to each other.
       
    • Triple runway configuration is when all three east/west runways are used, with one runway used in a mixed-mode and the other two in dedicated-modes.
      • For example, using Runway 23 in mixed-mode, and then using Runway 24R for departures and Runway 24L for arrivals.
       

    Our throughput rate (the number of arrivals and departures) is greatest when we’re on a triple configuration, followed by a dual configuration. In periods of low traffic, we can operate in a single or a land 1/depart 1 configuration.

    Why is this important? Our north/south runways can’t be used in a dual mode because of their proximity to one another, which means our capacity is impacted when we are on that configuration. This is a factor we need to consider when looking at initiatives such as the Idea 5: Summer Weekend Runway Alternation Program.

    Runway Operations at Toronto Pearson

    A number of factors are considered in determining which runways will be used at a given time, including:

    • Meteorological conditions such as wind direction, wind speed and weather
    • Runway conditions and availability (e.g. construction, maintenance, snow removal)
    • Operational efficiency and capacity
    • Aircraft type
    • Time of day

    During calm winds, we can use any of the five runways at Toronto Pearson, and so factors such as capacity needs or runway availability come into play.

    As the prevailing winds in the area are from the west, the most common runway configuration at Toronto Pearson supports a westerly flow, which means arrivals from the east and departures to the west using Runways 23, 24L 24R.

    The second most common configuration supports an easterly flow, with arrivals from the west and departures to the east using Runways 05, 06L and 06R. Our three east/west runways also provide us with the most capacity.

    How does weather and/or wind impact which runway is used?

    When the surface winds are too strong for aircraft to land and depart in the easterly or westerly configurations, NAV CANADA’s Air Traffic Controllers can re-assign runways to allow aircraft to land and depart into the wind. Since upper winds (or winds aloft) often increase with altitude, these may affect ATC’s decision to move to an “into the wind” configuration.

    Runway conditions are also a factor. Since friction is reduced in wet or snow-covered runway conditions, a lower wind speed level will prompt an ‘into the wind’ runway assignment than when operating in dry runway conditions.

    Additionally, anti-ice treatment and snow clearing of runways means that a runway can be temporarily unavailable, requiring alternate runway assignment.

    Preferential Runways

    As a best practice, many airports have provisions to operate their runways to enable aircraft to avoid noise-sensitive areas at certain times of day. We know aircraft noise can be more bothersome to our neighbours during the night, so we have defined overnight hours where the airport is configured to arrive and depart aircraft on “Preferential Runways”.

    The goal of the Preferential Runway system is to minimize the total population impacted. The defined Preferential Runway hours at Toronto Pearson are 12:00 a.m. to 6:30 a.m. every day. It’s important to note that these runways are just preferential, not mandatory.

    There may be times when we need to utilize runways outside the Preferential Runway system, for example due to strong winds or runway construction. This is important background to understand for Idea 6: Review of the Preferential Runway System.

    The current Preferential Runways in order are:

    Arrivals

    1. 05
    2. 15L
    3. 06L

    Departures

    1. 23
    2. 33R
    3. 24R

    Visual Flight Rules (VFR)

    Visual Flight Rules are rules that govern the procedures for conducting flight under visual conditions. These can be used when the weather conditions allow the pilot to see where the aircraft is going.

    Instrument Flight Rules (IFR)

    When visual references are obscured because of poor weather conditions or during the night, flight visibility is hindered. In these conditions aircraft are operated under IFR, and rely on defined standard procedures which are designed for all aircraft to operate. Aircraft can operate under IFR even when visual conditions do not require them to do so.

    Instrument Landing System (ILS)

    A precision instrument approach system, the ILS provides aircraft with precision vertical and horizontal navigation guidance information during approach and landing.

    Standard Instrument Departures (SIDs) and Standard Terminal Arrival Routes (STARs)

    When pilots fly from airport to airport using Instrument Flight Rules (IFR), they use standard published routes that act like roads in the sky and take them from point to point along their journey.

    When taking off, pilots use Standard Instrument Departures (SIDs) to get to the first point along their route. And when they reach their destination, they use Standard Terminal Arrival Routes (STARs) to move from the en-route portion of the flight onto the final approach path.

    STARs and SIDs are mapped out by waypoints (named points) in the sky to help pilots align with the final approach phase of flight. The existence of a published SID or STAR doesn’t mean it’s the only route an aircraft will follow. Air Traffic Controllers may direct pilots to operate off the SID or STAR for reasons related to safety and/or efficiency. For example, during periods of low traffic, air traffic controllers may direct aircraft to take a more direct approach to reduce the time it takes to get on the ground.

    Arrival Flight Paths

    Arriving aircraft often follow “U” shaped arrival flight path, which is used by Air Traffic Controllers to manage traffic. We talk about the u-shape in the following way:

    • The downwind is when aircraft fly past the airport parallel to, but in the opposite direction of the landing runway before joining the base leg
    • The base leg is when the aircraft is turning at a right angle from the downwind to the final approach
    • Final approach is when the aircraft is aligned with the runway and getting ready land

    Noise Abatement Procedures

    Toronto Pearson has a set of Noise Abatement Procedures that aircraft flying in and out of the airport are required to follow.

    • An arriving aircraft needs to be at 3000’ Above Sea Level (ASL) – equivalent to 2400’ Above Ground Level (AGL) – when it begins its final approach to the runway.
    • Departing aircraft are required to reach an altitude of 3600’ ASL (3000’ AGL) prior to making a turn from the runway heading. However, turns lower than 3000’ AGL (early turns) are permitted for propeller aircraft between 6:30 a.m. and 11:30 p.m. and for select eligible jet types between 7:00 a.m. and 11:00 p.m.

    It is important to understand SIDs and STARs, arrival flight paths and our noise abatement procedures when reviewing Idea 1: Nighttime approaches and Idea 2: Nighttime departures.

    Continuous Descent Operations

    Continuous Descent Operations (CDO), also known as Continuous Descent Approach (CDA), is a method by which aircraft approach airports prior to landing. It is designed to reduce fuel consumption and noise compared to other conventional descents. Instead of approaching the airport in a step-down fashion, throttling down and requesting permission to descend to each new (lower) altitude, CDO allows for a smooth, constant-angle descent to landing.

    NAV CANADA is proposing to increase CDO as part of Idea 4: Continuous Descent, which can be leveraged using satellite based navigation technology (Performance Based Navigation). Learn more about Performance Based Navigation below.

    Performance Based Navigation (PBN)

    Performance Based Navigation (PBN) are routes that use satellites and onboard equipment for navigation with enhanced accuracy. Previously, pilots flew from one ground-based radio transmitter to another which added flying time.

    With PBN, aircraft can fly more directly using satellite signals which reduces flying time, fuel consumption and GHG emissions. The International Civil Aviation Organization (ICAO) has recommended that States develop a plan for the implementation of PBN-related technologies and procedures. PBN describes the aircraft required navigation performance and through a set of navigation specifications that include both Area Navigation (RNAV) and Required Navigation Performance (RNP) specifications. Each navigation specification defines aircraft and aircrew requirements needed to support a navigation application within a defined airspace.

    Area Navigation (RNAV)

    Area Navigation (RNAV) is a type of PBN that allows aircraft to fly a defined route using station-referenced navigational aids (usually satellites) or on-board navigational equipment, or a combination of these. This technology is in used at airports around the world, including Toronto Pearson, and is essential to providing an airspace structure that supports safe sequencing at high traffic volume airports.

    Required Navigational Performance (RNP) and Required Navigational Performance – Authorization Required (RNP AR)

    Required Navigation procedures are similar to RNAV but also include on-board performance monitoring and alerting. It allows for even more efficient and flexible use of airspace than with RNAV. On-board performance monitoring and alerting allows RNP operations to provide an additional level of safety and capability over RNAV operations.

    RNP systems allow an aircraft to fly a specific path between two 3D-defined points in space. This allows for the design of flight paths that are shorter and that provide for a continuous descent – reducing flying time, greenhouse gas emissions and noise. RNP AR systems are used in obstacle-rich environments, where a higher level of navigation performance better able to address issues of airport access is required, and more recently have been adopted for improved operational efficiency, particularly at larger airports. The operator must meet additional aircraft and aircrew requirements, and obtain prior operational authorization from the regulatory authority before operating.

    About Noise Modelling

    The GTAA and NAV CANADA undertook noise modelling to understand the benefits and impacts of the options being proposed as well as to assist in communicating them. Since the proposals affect different aspects of aircraft operations at Toronto Pearson, the best noise modelling metrics were used for each idea. These include the use of single event, average and threshold modelling.

    For proposals that put forward a specific change to a flight path – such as those presented in ideas 1, 2, and 4 – single event noise modelling was used. This allows for the easy comparison of the noise footprint between existing and proposed flight paths by showing what the noise footprint would look like if a single aircraft flew the respective procedures. This footprint is known as the Single Event Lmax contour. While some of our maps show the footprint as a static contour, it’s important to understand that noise events are temporary. For comparison purposes, a 737-800 was used to show single event noise footprints.

    The proposals related to runway utilization and operations over a longer time period were considered – such as those presented in ideas 5 and 6 – a mix of average and threshold metrics were used. Threshold metrics allow us to project how many times a certain noise level will be reached (Number Above).

    Average measures, such as CNEL (Community Noise Equivalent Level), allow us to compare what the average exposure over a specified time period will look like both before and after a proposal. CNEL is the average sound level over a specified period, with a penalty of 5 dB added for 7:00 p.m. to 10:00 p.m., and a penalty of 10 dB added for of 10:00 p.m. to 7:00 a.m. Average metrics take in to account all the noise events. Single event levels (Lmax) cannot be effectively compared against average levels such as CNEL. Rather, one must compare CNEL noise footprints to other CNEL footprints and Single Event Lmax footprints to other Single Event Lmax footprints.

    You can find even more helpful terms in our glossary.