Did you know that a strobe light is permitted as
an aerodrome beacon? Did you know that rotating beacons are permitted on
communications towers? How come this was allowed to happen? What is COPA doing
about it?
Here is a primer on lighting and marking of obstructions, including some recent
developments that will bring about an improvement in the control of new
installations.
Obstruction marking and lighting is something that most of us take for granted.
It used to be quite simple.
Obstructions greater than a certain height were marked with red lights by night,
sometimes flashing at a rate of 40 per minute, and painted alternately red and
white for recognition during the day.
Rotating beacons at aerodromes were white, much brighter and rotated at six
revolutions per minute.
Night obstruction lighting was limited to an apparent lower intensity than
Aerodrome beacons, making them easily recognizable over background lighting and
flashing or steady tower lighting.
The Canadian Aviation Regulations (CAR 602.19) was loosely worded in terms of
compliance.
Transport Canada could require that an obstruction be marked and lit, but there
was no requirement to inform Transport Canada so that they could decide if
marking and lighting were required.
There were voluntary standards for marking and lighting towers and, for the most
part, the communications industry did the right thing and complied.
But the standards were written in the permissive “should” instead of the
imperative “shall.”
This control, or relative lack thereof, was fine in the good old days. Towers
were few and far between, the vast majority were marked on maps and there were
relatively few NOTAMs for new ones.
However, with the rapid growth in demand for cellular telephones and changes in
technology, problems have occurred that highlight the need for better control.
The proliferation of towers brought much more potential for conflicts with
aviation. Then there was the development of strobe light technology, whose
bright flash capability made it possible to mark towers with lights during the
day and night instead of periodically having to re-paint towers.
At about the same time (about 10 years ago), the aerodrome beacon standard
changed, for various reasons, to permit white strobes and the rotation or flash
rate was changed to 20-30 flashes per minute.
Not much notice was taken by anyone of the potential for confusion with tower
strobes because there was virtually no beacon strobes installed at aerodromes
anyway. The most frequent use of strobes as aerodrome beacons came with
heliports, but they are differentiated from other strobes by emitting a coded
pulse for the Morse Code letter ‘H.’
But then along came an obstruction light manufacturer whose interpretation of
“flashing” for obstruction marking included a narrow beam rotating beacon, which
was accepted by Transport Canada.
It “flashes” at 40 per minute, slightly faster than aerodrome beacons but not
noticeably so, unless they are side-by-side. In addition, it is just about the
same intensity as an aerodrome beacon.
Because of its competitive price, it has been purchased by several
communications companies and there are now approximately 300 of them installed
in Canada, particularly in Quebec, Ontario and British Columbia.
One thing that is peculiar about the approval process for lights is that
Transport Canada does not test or approve of them. Instead, it requires that
manufacturers get independent testing to prove that a new light meets the
Standard.
In addition, new technology is coming along for new types of lights involving
LEDs. There are already a substantial number in place at this time but the low
intensity red light specification is under review at this time.
The changes that have crept in over the years have led to the need for a review
of the Regulation and the Standard governing the installation of markings and
lighting. COPA is part of a Working Group that is developing a more enforceable
Standard and at the recent Canadian Aviation Regulations Advisory Council (CARAC)
meeting, COPA was involved in passing a revised Regulation that makes it
imperative for anyone planning to erect a building, structure or any other
object to advise Transport Canada so that a decision can be made about what
marking and lighting is required.
In other words, the permissive “should” that is currently in the standard is
being changed to an imperative “shall.”
Another important amendment suggested by COPA and accepted was a requirement for
notification to Transport Canada of any planned obstruction, regardless of
height, that is within six kilometres of an aerodrome.
It was also agreed at the CARAC meeting that there is confusion introduced by
the rotating obstruction light and it must be resolved.
COPA raised the additional issue of a lack of information in the Canada Flight
Supplement (CFS).
It does indicate where aerodrome beacons are in place but it does not indicate
whether it is a rotating or strobe type. Transport Canada agreed that more
information in the CFS is required.
Although the Regulation was passed at the CARAC meeting, it will have to wait to
go through the promulgation process until the Standard is completed, which will
probably require a few more Working Group meetings for alternatives to be
explored to better differentiate between aerodrome beacons and obstruction
lights. And with the current delays being experienced in the rule-making
process, due to a backlog in the legal vetting of draft Regulations, we do not
expect the Regulation and Standard to be in place for at least a couple of
years.
In the meantime, Transport Canada agreed that an Aviation Notice will be put out
in the near future to highlight the continuing potential for confusion.
Here is a summary of the issues:
•Aerodrome beacons can be rotating or strobe types. The type installed at a
particular aerodrome is not detailed in the CFS.
•Aerodrome beacons and rotating obstruction lights are of approximately the same
intensity and brightness compared with surrounding lighting and other
obstruction lights.
•Aerodrome beacons rotate or flash at 20-30 per minute whereas obstruction
lights rotate or flash at 40 per minute. This difference is difficult to
distinguish in most cases.
•Obstruction strobe lights are high intensity during the day, and lower
intensity at night.
•Aerodrome beacons are always white whereas obstruction lights can be white
strobes or red incandescent.
COPA is working towards solutions to these issues but it will take time to bring
them into place. In the meantime, we hope you are enlightened by this article
and more aware that there is potential for confusion between aerodrome beacons
and obstruction lights.