Part VI - General Operating and Flight Rules

Canadian Aviation Regulations (CARs) 2017-2

Standard 621.19 Appendix B Obstruction Lighting Specifications

Content last revised: 2000/06/01  

1. Design Requirements

(a) General

This Appendix sets out the detailed technical design specifications applicable to obstruction marking and lighting standards.

(b) Classification of Obstruction Lights

Name Colour Intensity Type Chapter
CL-810 Red low Steady burning red lights 5
CL-864 Red medium Red flashing lights 5
CL-865 White medium White flashing lights 6
CL-856 White high White flashing 7
CL-857 White high White flashing - catenary 8

(c) Definitions

(i) Beam Spread - The angle between the two directions in the vertical or horizontal plane in which the intensity is equal to 50 percent of the minimum specified peak beam effective intensity.

(ii) Vertical Aiming Angle - The angle formed between the horizontal and a line through the centre of the vertical beam spread.

(iii) Steady-Burning Light (Fixed Light) - A light having constant luminous intensity when observed from a fixed point.

(iv) Effective Intensity - The effective intensity of a flashing light is equal to the intensity of a steady-burning (fixed) light of the same colour which produces the same visual range under identical conditions of observation.

(d) Applicable Documents

(i) The following Military Standards and Specifications, as amended from time to time, apply to the specifications contained in this Appendix, to the extent stipulated below:

MIL-STD-810: Environmental Test Methods

MIL-C-7989: Covers, Light-Transmitting, for Aeronautical Lights, Specification for.

(e) Environmental Requirements - Obstruction lighting equipment is designed for continuous operation under the following conditions:

(i) Temperature: -55° C to +55° C.

(ii) Humidity: 95 % relative humidity.

(iii) Wind: Wind speeds up to 240 km/hr.

(iv) Wind-blown Rain: Exposure to wind-blown rain from any direction.

(v) Salt Fog: Exposure to salt-laden atmosphere.

(f) Light Unit - The light unit is compact, lightweight, and designed for easy servicing and lamp or flash tube replacement. Materials used within the light unit are selected for compatibility with their environment.

(g) Light Covers - Light-transmitting covers for light units conform to the requirements of MIL-C-7989.

(h) Light Colours - Red light systems should emit aviation red defined in accordance with the International Commission on Illumination (CIE) chromaticity diagram with the "y" co-ordinate not exceeding 0.335. Xenon flashtube emission is acceptable for white obstruction lights.

(i) Aiming for CL-856 and CL-857 (high intensity white flashing) - CL-856 and CL-857 light units have a method for adjustment of the vertical aiming angle between 0 and + 8 degrees. A spirit level or other device is provided as part of each light unit for setting the elevation angle of the light beam, and an indicator shows the elevation angle with an accuracy of ±1°.

(j) Control Unit

Control unit of a lighting system meets the following criteria:

(i) White Obstruction Lighting Systems

(A) Medium Intensity Lights - The control unit sets the system’s flash rate, flash sequence, and light intensity. The power and control functions may be consolidated in a single box with the light unit or may be distributed into several units.

(B) High Intensity Lights - The control unit sets the system’s flash rate, flash sequence, and light intensity. The system is designed for operation with light units located up to 800 m from the control unit. If the timing circuit fails, the light units continues to flash randomly or in accordance with Table 6. Failure of an intensity step change circuit will cause all light units to operate at the high intensity step. An override switch is mounted on the control unit to manually control light intensity during maintenance or in the event of a photometric control malfunction.

(C) Monitoring - The control unit monitors the specified operating mode of the flash lamp in a system. The operating status of each light unit in the system is displayed at the control unit. The control unit has provisions to permit connection of a remote indicator, supplied by others or as an option, which indicates the system status.

(ii) Red Obstruction Lights - Control units for these light systems are optional. When provided, control units are capable of providing more than one or more of the following functions:

(A) On/Off photometric control;

(B) Lamp failure monitor/remote display.

(k) Input Voltage - The obstruction lighting equipment is designed to operate from the specified voltage ±10%.

(l) Transient Protection - The power input, control, and monitor interface circuitry is designed to withstand line to ground surges up to 5kv for 10 milliseconds (ms) duration.

(m) Warning Labels - All enclosures which contain voltages exceeding 150 volts have high voltage warning label(s) placed at a conspicuous location(s).Warning labels are in French and English.

(n) Interlock Switches - Interlock switches are incorporated in the control unit and power supplies so that opening the enclosure has the effect of (1) disconnecting incoming power and (2) discharging all high voltage capacitors to 50 volts within 30 seconds.

(o) Component Ratings.

(i) Discharge Lighting Equipment - All components on discharge lighting equipment, including the flashtube, are designed for ease of servicing and meet performance requirements for a minimum of one year without maintenance.

(ii) Incandescent Lighting Equipment - All components in incandescent lighting equipment, except lamps, are designed to meet performance requirements for a minimum of 1 year without maintenance. Lamps have a minimum rated life of 2000 hours at rated voltage.

(p) Performance Requirements

(i) Photometric

Lighting systems meet the following photometric requirements:

(A) General - The effective intensity for flashing lights are calculated in accordance with the following formula:

Where:

Ie = Effective Intensity (Candelas)

I = Instantaneous Intensity (Candelas)

t1, t2 = Integration limits (seconds).

The limits of integration are selected so that the value of Ie is maximized.

For discharge flashing lights, the equipment provides the specified light output at the specified temperature extremes as the input voltage simultaneously varies by ±10% from nominal. The light intensity and beam distribution requirements for obstruction lighting equipment are specified below. All intensities listed are effective intensities (except steady-burning red obstruction lights) measured at the flash rate specified in Table 6.

(B) CL-810 (steady burning red) Light Unit - The CL-810 light unit meets the photometric requirements of Table 1.

Table 1

Angle (degrees above the horizontal) Intensity (percentage) (1)
15 to 0 5
0 to 2.5 40
2.5 to 12.5 100
12.5 to 15 40
15 to 30 15
30 to 90 5

Note (1): 100 percent is 32.5 candelas.

(C) CL-856 (high intensity white flashing - general) Light Unit - The beam spread and effective intensity is in accordance with Table 2.

Table 2

  Beam Spread  
Step Horizontal (degrees) (1) Vertical (degrees) Peak Intensity (candelas)
Day 90 to 120 3-7 270,000 ±25%
Twilight 90 to 120 3-7 20,000 ±25%
Night 90 to 120 3-7 2,000 ±25%

NOTE (1): Multiple light units may be used to achieve a horizontal coverage of 180 or 360 degrees.

Spec Note: Chapter 7 of this Manual stipulates a minimum peak intensity of 200,000 candelas. The day value of Table 2 is given as 270,000 candelas for which 75 % is 202,500 candelas.

(D) CL-857 (high intensity white flashing - catenary) Light Unit - The white flashing high intensity light unit has a beam spread and effective intensity in accordance with Table 3.

Table 3

  Beam Spread  
Step Horizontal (degrees) (1) Vertical (degrees) Peak Intensity (candelas)
Day 90 to 120 3-7 140,000 ±25%
Twilight 90 to 120 3-7 20,000 ±25%
Night 90 to 120 3-7 2,000 ±25%

NOTE (1): Multiple light units may be used to achieve a horizontal coverage of 180 or 360 degrees.

Spec Note: Chapters5 and 6 of this Manual stipulate a minimum peak effective intensity of 100,000 candelas. The day value of table 3 is given as 140,000 candelas for which 75% is 105,000 candelas.

(E) CL864 (red flashing beacon) Light Unit - The vertical beam spread has a 3 degrees minimum. The lower edge of the vertical beam spread lies between -1.5 and -0.5 degrees. Photometric requirements are in accordance with Table 4.

Table 4

  Beam Spread  
Step Horizontal (degrees) Vertical (degrees) Peak Intensity (candelas)
Single 360 3 minimum 2,000 ±25 %

(F) CL-865 (medium intensity white flashing) Light Unit - The vertical beam spread is three degrees minimum. The lower edge of the vertical beam spread lies between -1.5° and -0.5°. Photometric requirements are in accordance with Table 5.

Table 5

  Beam Spread  
Step Horizontal (degrees) Vertical (degrees) Peak Intensity (candelas)
Day/Twilight 360 3 minimum 20,000 ±25%
Night 360 3 minimum 2,000 ±25%

(ii) Flash Rate and Duration - The flash rate and duration is in accordance with Table 6.

Table 6 - Flash Characteristics for Obstruction Lights

Type Intensity Step Flash Rate (fpm)(1) Flash Duration (2)
CL-856 Day and Twilight 40 Less than 10 ms
CL-856 Night 40 Between 100 and 250 ms inclusive
CL-857 Day and Twilight 60 Less than 10 ms
CL-857 Night 60 Between 100 and 250 ms inclusive
CL-810 Single 20 - 40 1/2 to 2/3 of flash period note (3)
CL-865 Day and Twilight 40 Less than 10 ms
CL-865 Night 40 Between 100 and 250 ms inclusive

NOTES:

(1) Flash rates have a tolerance of ±5%.

(2) When the effective flash duration is achieved by a group of short flashes, the short flashes are emitted at not less than 30 per second.

(3) The light intensity during the period is not less than 10% of the peak effective intensity. The off period is at least 1/3 of the flash period.

(iii) System Flashing Requirements

(A) Simultaneous Flashing Systems - All obstruction lights in systems composed of CL-856, and/or CL-864, and/or CL-865 light units flash simultaneously. The flash rate is in accordance with Table 6.

(B) Sequenced Flashing Systems - Systems composed of CL-857 (white flashing high intensity) light units have a sequenced flash characteristic. This system consists of three lighting levels on or near each supporting structure:
- one level is near the top;
- one level midway between the top and bottom; and
- one level at the bottom or lowest point of the catenary.

The flash sequence is middle, top and bottom. The interval between top and bottom flashes is about twice the interval between middle and top flashes. The interval between the end of one sequence and the beginning of the next is about 10 times the interval between middle and top flashes. The time for the completion of one cycle is one second (±5%).

(iv) Intensity Step Changing - The intensity or mode change (on/off) for each of the obstruction lighting systems is stipulated in Chapters5, 6, 7 and 9. Change of intensity or mode is controlled by means of a photocell device which is installed to sense the ambient background illuminance (lux) of the north sky. The photocell settings are in accordance with Table 7.

Table 7

Step Ambient Luminance
Day to twilight 600 - 300
Twilight to night 50 - 20
Night to twilight 20 - 50
Twilight to day 300 - 600

2. Quality Assurance Testing

(a) Qualification Tests - Photometric and system operational tests are conducted after completion of all environmental tests. The same obstruction lighting units are used throughout the tests. The purpose of the following tests is to demonstrate compliance with these specifications. The tests may be run on the control unit, power supply, and a single light unit, with a simulated load replacing the other light units. Equipment tested are completed with optional equipment.

(b) High Temperature Test - The high temperature test is conducted in accordance with MIL-STD-810, Method 501.2, Procedure II. The equipment is subject to a constant temperature of at least +55° C for four hours after temperature stabilization. The equipment is then turned on for testing. The owner/operator of the obstruction lighting ensures that the manufacturer has demonstrated during the test that the equipment maintains the proper flash rate and (for discharge flashing light) the proper amount of energy is being delivered to flashing light) the proper amount of energy is being delivered to the lamp as the input voltage is varied by ±10% from nominal and that a visual examination has been conducted after the equipment was removed from the test chamber. Failure of the equipment to operate properly or any deterioration in materials constitutes failure of the test.

(c) Low Temperature Test - The low temperature test is conducted in accordance with MIL-STD-810, Method 502.2 Procedure II. The equipment is placed in a chamber which maintains a temperature of -55° C or less. Equipment, with input power off, is then exposed to a 24-hour soaking period after which the equipment is turned on for 1 hour, and achieves proper flash rate and intensity within 30 seconds after being energized. The owner or operator of the building, structure or object on which the lighting equipment is used ensures that the manufacturer has demonstrated during one hour of operation as part of the test that the equipment maintains the proper flash rate and (for discharge flashing light) the proper amount of energy is being delivered to the lamp as the input voltage is varied by ±10% from nominal and that, at the conclusion of the test, a visual inspection has been be conducted. Failure of the equipment to operate properly or any deterioration in materials constitutes failure of the test.

(d) Rain Test - The wind-blown rain test is conducted in accordance with MIL­STD­810, Method 506.2, Procedure I. The rain is at a rate of 130 mm/hour with an exposure time of 30 minutes per side. The equipment is operated throughout the test. Failure of the equipment to operate properly, or any deterioration in materials, or excessive accumulation of water in the equipment constitutes failure of the test.

(e) Wind - Evidence is provided, either by testing or by calculated mechanical force, to demonstrate that installed light units meet the wind requirements in paragraph 1(e)(iii).

(f) Humidity Test - The test is in accordance with MIL-STD-810, Method 509.2, Procedure I. The equipment is subjected to three complete cycles (71 hours) according to Table 507.2-I, except the maximum temperature at cycle 1 should be +55° C. Failure of the equipment to operate properly or any deterioration in materials constitutes failure of the test.

(g) Salt Fog Test - The salt fog test is conducted in accordance with MIL-STD-810, Method 509.2, Procedure I. Failure of the equipment to operate properly or any evidence of damage, rust, or corrosion in materials constitutes failure of the test.

(h) Photometric Test - Light units are energized by system power supply and control unit, and tested for compliance with the photometric requirements set out above. For a discharge flashing light, the specified intensity is produced at high and low temperature extremes as the input voltage to the system power supply varies by ±10% from nominal. Red light intensity may be measured in white light and then calculated if the glassware manufacturer certifies the chromaticity and transmissivity values of the red filter material for the particular source. If more than one lamp type is to be used, the qualification testing is completed for each lamp type. For a discharge flashing system, if the power supply and optical head are separate components, the owner or operator of the building, structure or object on which the equipment is installed ensures that the manufacturer has demonstrated that the required photometrics are produced with the units separated by maximum and minimum recommended distances and connected by cable recommended by the manufacturer. Photometric test results are in the forms of:

(i) Vertical beam pattern: Distribution curve (vertical angle versus candelas).

(ii) Horizontal beam pattern: Polar plot (horizontal angle versus candelas).

(i) System Operational Test - System components are connected with the necessary wiring to electrically simulate an actual installation in which the top and bottom light units on a structure are separated by 600 m for a system composed of CL-856 or CL-865, and 150 m for system composed of CL-857, and the controller separated an additional 800m. Simulated interconnecting cables with equivalent impedances may be used in lieu of full cable lengths. The system is energized and operated to demonstrate compliance with all specification operating requirements such as flash rate, flash sequence, photoelectric switching of intensity steps, operation of interlock devices and satisfactory operation under input voltage variations. If the power supply and optical head are separate components, it is demonstrated that with the maximum recommended separation between components, sufficient energy is delivered to the light unit to produce the specified photometrics. This test is modified to verify the specific requirements for single CL 810 and a system composed of CL 810 and CL 864 lights.

(j) Visual Examination - The obstruction lighting equipment is examined for compliance with the requirements on materials, finish and quality of workmanship.

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