EXEMPTION FROM CHAPTER 15 AIRCRAFT DETECTION SYSTEM (ADS) OF STANDARD 621 MADE PURSUANT TO PARAGRAPH 601.24(2)(a) OF THE CANADIAN AVIATION REGULATIONS

From: Transport Canada

Pursuant to subsection 5.9(2) of the Aeronautics Act, and after taking into account that the exemption is both in the public interest and is not likely to adversely affect aviation safety, I hereby exempt the person who has responsibility for or control over the building, structure or object to mark and light it in accordance with the requirements of Standard 621 and who plans to install or modify an (aircraft detection system) ADS without provision of an audio signal (except for catenary crossings) from the requirements of Chapter 15 of Standard 621 - Aircraft Detection System (ADS), specifically pertaining to the provision of an audio signal, which is made pursuant to paragraph 601.24(2)(a) of the Canadian Aviation Regulations (CARs), subject to the conditions set out below.

Details of CAR 601.24(2)(a) and Chapter 15 – Aircraft detection system (ADS) of Standard 621 are set out in Appendix A of this exemption.

Purpose

The purpose of this exemption is to enable persons who have responsibility or control over obstacles, except for catenary crossings, to do an installation or a modification of an installation of an ADS without provision of an audio signal, as specified in Standard 621, Chapter 15.

Application

This exemption applies to the person who has responsibility for or control over the building, structure or object to mark and light it in accordance with the requirements of Standard 621 and who plans to install or modify an ADS without provision of an audio signal.

This exemption does not apply to catenary crossings [suspended cable such as for an electricity transmission line or ski-lift].

Conditions

This exemption is subject to the following conditions:

  1. Prior to the installation or the modification of an ADS, the person shall provide to the Minister a description of the proposal in the Aeronautical Assessment form for Obstacle Marking and Lighting prescribed in Appendix C of Standard 621.
  2. The person shall sign the form and submit it for review to the applicable regional office of Transport Canada, as set out in Appendix A of Standard 621.

Validity

This exemption is in effect until the earliest of:

  1. August 26, 2017 at 23:59 EST;
  2. the date on which any of the conditions set out in this exemption is breached;
  3. the date on which the exemption is cancelled by the Minister, in writing, where she is of the opinion that it is no longer in the public interest, or that it is likely to adversely affect aviation safety.

Dated at Ottawa, Ontario, Canada on this 12th day of September 2014, on behalf of the Minister of Transport.

“Original signed by Aaron McCrorie (for)”

Martin J. Eley
Director General
Civil Aviation
Transport Canada

Relevant CARs excerpts:

601.24

  1. Any person who plans to construct or modify a building, structure or object, or launch a tethered object shall notify the Minister of the proposed construction, modification or launch in accordance with the requirements of Standard 621 if the building, structure or object, or tethered object, will constitute an obstacle to air navigation.
  2. A person who has responsibility for or control over a building, structure or object that constitutes an obstacle to air navigation shall
    1. mark and light the building, structure or object in accordance with the requirements of Standard 621; or
    2. use the equivalent marking and lighting approved by the Minister under subsection 601.27(2).

SOR/2011-285, s. 6.

Relevant Standard 621 excerpts:

CHAPTER 15 ─ AIRCRAFT DETECTION SYSTEM (ADS)

15.1 Scope

Chapter 15 governs Aircraft Detection Systems (ADS) which are used to turn on obstruction lighting systems upon detection of an approaching aircraft. The system is radar based and can detect and analyze the flight path [position, altitude, heading and ground speed] of an aircraft so as to determine the possibility of potential collision with an object. If the flight path is such that the aircraft may impact the obstacle, then the obstacle lights are turned on and a later audio signal is transmitted. The purpose of the system is to enable the lighting to be off when not needed [absence of aircraft] and thereby to reduce energy consumption, and glare to the public.

15.2 Impact Boundary

  1. The impact boundary is a 3-dimensional boundary around the obstacle approved by the Minister, so as to establish the distance [in terms of seconds] from the location of the detected aircraft to a point of impact on this boundary.
  2. The impact boundary is at a distance of 60 m to 300 m from the actual physical sides of the obstacle, as shown in Figure 15-1.

Note: An impact boundary for a catenary is shown in Figure 15-1. Different shapes of impact boundary may be required for different obstacles. In the case of lengthy or large area objects, more than one ADS radar may be required.

  1. In vertical dimension, the impact boundary extends 60 m above the highest portion of the obstacle.

15.3 Operation

  1. The system has two primary functions: to turn on the obstacle lights and to emit an audio signal. These functions are performed with respect to the detection of the aircraft within a specified minimum flight time to the impact boundary for both a heading directly towards the impact boundary as well as a potential manoeuvre towards the impact boundary.
  2. The system has the following minimum timings for light and audio signal activation with respect to the speed of the aircraft and time from the impact boundary:

Aircraft speed
knots

Aircraft speed
m/s

Time from Impact Boundary
(seconds)

90

46.3

30

120

61.7

30

165

84.9

30

180

92.6

30

250

128.6

20
  1. Potential Manoeuvre to Impact Boundary

Note:The following addresses the case of aircraft that are not on a direct flight path to impact, but have the potential for impact.

  1. The ADS detects and causes light and audio signal activation per 15.3.2 for aircraft flying in the horizontal plane that would have a potential of impact if it were to conduct a turning manoeuvre of up to 2g. Refer to Figure 15-3.
  2. The ADS detects and causes light and audio signal activation per 15.3.2 for aircraft flying in the horizontal plane that would have a potential of impact if it were to conduct a descent of rate of up to 2.5m/s [500 ft per minute]. Refer to Figure 15-3.
  1. Lighting
    1. Once the lighting is activated upon aircraft detection, the lighting is maintained on for a period of at least 60 seconds.
    2. The lighting for use with ADS is of a design such that it will provide full intensity within 2 seconds of activation.
  2. Audio Signal
    1. The audio signal consists of a 3 note chime followed by a worded message indicating the type of obstacle as determined locally. For example, for a catenary crossing, the term "power line" may be used. The signal is repeated a total of 6 times for slow speed aircraft and 3 times for high speed aircraft [>250 knots], for a total duration of 12 seconds and 6 seconds respectively.
    2. The audio signal is limited in range so as to not interfere with other non-ADS broadcasts. The limitation of range is tested using standard General Aviation VHF radio and antenna equipment while the ADS VHF transmitter is transmitting a continuous test signal, range limit is where the perceived signal quality comes below level 4.

Note 1: A limited range represented by a volume of space defined by a cylinder centred on the ADS unit with a radius of 7 km and height of 1.8 km, is recommended.

Note 2: In the radio terminology, the quality of the radio signal is rated on a scale from 1 through 5, where 1 is the worst (unreadable) and 5 is best. A quality of 4 is fully readable, when below 4 the audio signal is degraded below an acceptable level.

  1. The audio signal is broadcast simultaneously on multiple frequencies in the VHF band over the range of 118 to 136 MHz. The frequencies are selected as appropriate for local requirements.
  1. Warning Zones

Note: The ADS may be considered to establish "warning zones" around the obstacle based upon the timings for light activation and audio signal transmission in relation to the impact boundary.

  1. If the aircraft enters the audio signal warning zone, an audio signal is transmitted. If the aircraft remains within this zone no additional audio signals are provided. A new signal will be provided, if the aircraft leaves the zone and then re-enters.
  2. If the aircraft enters the light activation warning zone, the lights are turned on and will continue to be illuminated for the period specified in subsection 15.3.4. If the aircraft remains within this zone beyond the specified period, the lights will turn off. The lights will be re-activated, when the aircraft leaves the zone and then re-enters.
  1. Frequencies
    1. Audio signal radio broadcasts comply with applicable Industry Canada guidelines and permit requirements.
    2. The radar frequencies are selected so as to not cause interference with other radar operations.

15.4 Monitoring

The ADS has continuous electronic monitoring to detect failure of the major components.

  1. Radar or Communications Failure:The occurrence of failure of the radar or of the communication link to the lights cause the lighting to be turned on continuously, the audio signal deactivated and an alarm given to a 24 hour staffed station. There is provision for immediate issuance of a NOTAM from this station. The communication status and operational status of the system are confirmed at least once every 24 hours.
  2. Obstruction Lights Failure:If a light outage occurs, the audio warning function remains active, the monitoring station is notified and a NOTAM issued. Corrective action is taken as soon as possible to restore the light.

15.5 Self Test

Unless the system has been activated at least once within a 24 hour period by aircraft, the system is activated for self test at least once within a 24 hour interval to verify the operational status.

15.6 Radar Unit

The radar unit is provided with a battery backup supply having a capacity for 24 hours of operation, to enable communication of external power supply failure to the lights.

15.7 Submission of Application for Use

The design and function of each control device is described in the ADS application. The control device description includes:functionality, selectable features, program modification, maintenance actions, failure/monitoring provisions and any reporting functions. The reportable functions are described and the methodology detailed for accumulating information.

15.8 Commissioning Test
The ADS installation is subject to a commissioning test to verify:

  1. the required performance of the system,
  2. absence of any interferences of the radar unit with other radars in the area, and
  3. that the audio does not present a hazard to other aircraft communications not in proximity to the obstruction hazard.
Date de modification :

Report a problem with this page

Date modified: