Pearson Accountability Alliance

Noise Monitoring Terminals (NMTs) Around Toronto Pearson

Toronto Pearson’s operator, the Greater Toronto Airports Authority (GTAA), states that it has been “monitoring noise in neighbouring communities and areas under flight paths since the 1970s” and that there are currently 25 active Noise Monitoring Terminals (NMTs) distributed around the airport. These monitors feed into the Airport Noise and Operations Monitoring System (ANOMS).

Status of information requests

What the GTAA says about noise monitoring

According to the GTAA, NMTs are used to obtain objective data and assess aircraft noise levels. NMTs are one source of information that feeds into ANOMS, which correlates noise events with aircraft operations to create “Aircraft Noise Events”.

• “25 active Noise Monitoring Terminals (NMTs) in neighbourhoods around the airport.”
• Noise events are measured against a sound level threshold:
  • 65 dBA from 06:30 to 23:59
  • 60 dBA from 00:00 to 06:29 (lowered for nighttime)
• Noise events must last at least five seconds to be recorded.
• Recorded noise events are then checked against flight operations to flag “Aircraft Noise Events”.
• Pearson is federally regulated and “not bound to any municipal noise by-laws,” and there is no maximum legal noise limit; instead, the GTAA points to “noise abatement procedures” and “land use planning” as its main tools.

On paper, this sounds like a robust, science-based system. In practice, the story that affected communities experience on the ground is very different.

Noise-monitoring infrastructure around Pearson

The GTAA publishes a map of NMT locations distributed around Pearson. These monitors are presented as a permanent, reliable network that has been operating since the 1970s. However, the GTAA does not publish:

• Uptime / availability statistics for each monitor;
• Historical outage logs (dates, durations, and causes);
• Maintenance or calibration records; or
• Any formal trigger for public notification when a monitor goes offline.

This page documents the infrastructure that exists and the reliability failures that affected communities have been reporting for more than two decades.

Current Noise Monitoring Terminals (NMTs)

The following table lists the NMTs currently published by the GTAA.

Monitor-specific evidence summaries

Acacia Avenue / Acacia Park NMT – Evidence Summary

• Emails documenting outages beginning in 2023 and continuing in subsequent years.
• Known long-duration outage of approximately three months in 2023.
• Additional periods where local residents report the monitor as “flat-lined” while aircraft were clearly audible overhead at night.
• Repeated community attempts to obtain explanations and outage logs, with no detailed public accounting of downtime or reconstructed data.

Published Acacia Park noise data – 2025 (Pearson Accountability Alliance)

• Acacia Park Noise Monitor – 2025 summary page (monthly PDFs + XLSX datasets)

How Pearson’s NMTs count “noise events”

On the GTAA’s own description, a noise event at an NMT is only captured when two conditions are met:

• The sound level exceeds a threshold (65 dBA by day, 60 dBA at night); and
• The sound level stays above that threshold for at least five seconds.

If either condition is not met — for example, a very loud but brief overflight, or repeated peaks just below the threshold — the event may be invisible in GTAA’s statistics, even if residents experience it as highly disruptive in their bedrooms at night.

GTAA’s own 45 dB harm threshold

In its official Restricted Hours Operating Policy (Version 4.1, May 29, 2019), the Greater Toronto Airports Authority (GTAA) states that, during the restricted hours, it works with NAV CANADA to maintain flight procedures that “minimize the number of community residents that are overflown at a decibel rating above 45 dB”. In other words, GTAA itself treats 45 dB as the level beyond which nighttime aircraft noise exposure must be minimized for residents.

Yet in neighbourhoods such as Acacia Park, independently compiled data from the Acacia noise monitor show repeated nighttime events between 75 and 80 dB, and sometimes higher. On a logarithmic scale, an 80 dB event is perceived as more than 10 times louder than a 45 dB event. These are not rare anomalies; they are routine in the current operating pattern.

How GTAA uses NMT data to compare “aircraft” vs “community” noise

In addition to WebTrak and ANOMS, GTAA publishes interactive dashboards that claim to show how aircraft noise compares to “community” or “ambient” noise.

On these dashboards, the bars for “community” noise are often shown as equal to or higher than the bars for “aircraft” noise. On paper, this is then presented to communities, the media and policy-makers as proof that airplanes are not the main problem — that the real noise in neighbourhoods comes from the community itself.

For residents living under Pearson’s flight paths, these charts do not match lived experience. They are produced by the same institutions that control the aircraft, own the monitors, and design the thresholds. From a governance perspective, this is a built-in conflict of interest.

Examples: WebTrak views – Marvin Heights Public School monitor

The screenshots below show WebTrak views captured between December 29, 2025 and January 10, 2026. They are part of a community-maintained record of Marvin Heights Public School NMT behaviour that extends from 2023 onward. Across different days, weather changes, and traffic patterns, the Marvin Heights Public School NMT in Malton shows consistent signs of failure:

• Locked at abnormally high values, starting around 65 dB and ratcheting upward day after day into the high 70s, even when aircraft were distant;
• Not reacting to runway changes or traffic load, unlike neighbouring monitors;
• Staying at these inflated “background” levels for roughly three weeks, with no return to realistic community readings during the period observed; and
• No public notices from GTAA or NAV CANADA about the outage or misbehaviour.

This behaviour is consistent with a malfunctioning or stuck monitor—a serious issue for a system used to justify GTAA’s “community vs aircraft noise” comparisons. By inflating the supposed “community” baseline, the airport’s own dashboards can be used to claim that aircraft noise is lower than what local residents are generating themselves. It is an optical trick, not an honest picture of what people are living with at night.

Supporting documents for this section

• GTAA Restricted Hours Operating Policy v4.1.1 (PDF) — GTAA policy that acknowledges the need to minimize residents’ exposure above 45 dB at night.
• Sanitized 45 dB notification letter (PDF) — Correspondence alerting Transport Canada, Health Canada, GTAA and the Prime Minister’s Office that GTAA itself uses 45 dB as a harm threshold.
• ATI request to Transport Canada – NMT outage and reliability records (PDF)
• Joint NAV CANADA / GTAA request – NMT uptime and outage logs (PDF)

Additional screenshots and multi-year timelines for multiple NMTs (including Marvin Heights), covering outages and misbehaviour from 2023 onward, can be added as a ZIP archive on request.

Why NMT uptime matters for health and accountability

When monitors are offline, every missed night becomes a blank in the official record. Yet the aircraft still fly, and the noise still enters people’s homes.

When monitors are down, the harm is still real — but the data disappears. This systematically advantages the airport operator and disadvantages the residents, workers, and public-health systems that bear the cost.

Take Action: Demand an Independent Audit

The noise monitoring system is broken, opaque, and managed by the very organization causing the noise. Residents can use this page to email the Minister of Transport, copy their MP, and also notify their municipal council and local Board of Health.

Step 1: Turn this evidence into a formal record

Use the form below to generate a letter you can adapt for MPs, councils, Boards of Health, or media. You can copy the text or open it directly in your email program.

Step 2: Where to send this evidence

Use the tools below to send this evidence to federal, provincial, municipal and public-health decision-makers.

Evidence documents cited on this page

• GTAA Restricted Hours Operating Policy v4.1.1 (PDF)
• Sanitized GTAA 45 dB letter (PDF)
• ATI request to Transport Canada re: NMT outage and reliability records (PDF)
• Joint NAV CANADA / GTAA NMT failures correspondence (PDF)

For regulators, investigators, and auditors

A structured archive of noise-monitor outage emails (2003–2026), screenshots, and ANOMS/WebTrak discrepancies is available on request.

Please contact info@pearsonaccountabilityalliance.org for access to the full evidentiary package.

PAA’s position

Pearson operates on federal land under a Ground Lease with Transport Canada. After years of unresolved NMT failures, misleading public dashboards and escalating health impacts documented by residents, it is no longer credible for the federal landlord to look away.