TWO SIDED MARKER

BALISE A DEUX FACES

English Abstract

The marker has a pair of upwardly converging
reflectant planar panels facing approximately in opposite
directions. In its correct attitude on a support surface
the panels slope at 2°-6° to the vertical if the marker
is intended for assisting the landing of fixed wing aircraft
and at 8°-10° to the vertical if the marker is intended for
assisting the landing of helicopters. The reflectant panels
are preferably retroreflectant.

French Abstract

La balise a une paire de panneaux plats réfléchissants et convergeant vers le haut, orientés à peu près dans des directions opposées. Dans la disposition correcte sur une surface d'appui, les panneaux sont inclinés à 2.degrés.-6.degrés. par rapport à la verticale si la balise a pour but de faciliter l'atterrissage d'un avion et à 8.degrés.-10.degrés. par rapport à la verticale si elle a pour but de faciliter l'atterrissage des hélicoptères. Les panneaux réfléchissants sont, de préférence, rétroréfléchissants.

Claims

The embodiments of the invention in which an exclusive property or privilege
is claimed are defined as follows:
1. Marker for support on a support surface in a predetermined attitude,
comprising a pair of substantially planar panels, each of a size to be visible to a pilot
on a descent path, facing approximately opposite directions, and, in said attitude to
each slope toward the other, in an upward direction, said slope of each panel being at
an angle of between 2° and 10° to the vertical, each of said panels having
retroreflectant material covering a substantial area thereof.
2. Marker for assisting the landing of a fixed wing aircraft or helicopter, designed
for support on a support surface in a predetermined attitude, comprising a pair of
substantially planar panels facing approximately opposite directions, said panels being
more closely spaced from each other than the width of said panels and, to each slope
toward the other, in an upward direction, said slope of each panel in said attitude,
being at an angle of between 2° and 10° to the vertical, each of said panels having
retroreflectant material covering a substantial area thereof.
3. Marker for assisting the landing of a fixed wing aircraft or helicopter,
comprising a pair of substantially planar panels facing approximately away from each
other and each sloping toward the other at a convergence angle of between

4° and 20° and having retroreflectant material covering a
substantial area of each of said panels, said panels being
more closely spaced from each other than the width of said
panels.
4. In combination, an aircraft runway, a marker
therefor, and a support surface for said marker,
means for mounting said marker on said support
surface in a predetermined attitude,
said marker, when so mounted, comprising a pair
of panels facing approximately away from each other, said
panels, with said marker in said predetermined attitude,
sloping upwardly toward each other, and each sloping at an
angle of between 2° and 10° to the vertical, each panel having
retroreflectant material covering a substantial area thereof,
said panels being more closely spaced from each other than the
width of said panels.
5. Marker as claimed in claim 1 wherein, in said
attitude, each said panel slopes at an angle of 2° to 6° to
the vertical.
6. Marker as claimed in claim 2 wherein, in said
attitude, each said panel slopes at an angle of 2° to 6° to
the vertical.
7. Marker as claimed in claim 3 wherein said convergence
angle is 4° to 12°.
8. In combination as claimed in claim 4 wherein each
panel slopes at an angle of between 2° and 6° to the vertical.

9. Marker as claimed in claim 1 wherein, in said
attitude, each said panel slopes at an angle of 8° to 10°
to the vertical.
10. Marker as claimed in claim 2 wherein, in said
attitude, each said panel slopes at an angle of 8° to 10°
to the vertical.
11. Marker as claimed in claim 3 wherein said
convergence angle is 16° to 20°.
12. In combination as claimed in claim 4 wherein each
of panel slopes at an angle of between 8° and 10° to the
vertical.
13. Marker for support on a support surface in a
predetermined attitude, of a size to be visible to a pilot
on a descent path, comprising a pair of substantially planar
panels facing approximately opposite directions and, in said
attitude to each slope toward the other, in an upward direction
said slope of each panel being at an angle of between 2° and 10°
to the vertical, each of said panels having retroreflectant
material covering a substantial area thereof; wherein said
panels are formed of aluminum and said retroreflectant material
is a layer attached to the outwardly facing surface of each
panel.
14. Marker for assisting the landing of a fixed wing
aircraft or helicopter, designed for support on a support
surface in a predetermined attitude, comprising a pair of
substantially planar panels facing approximately opposite
directions, and,to each slope toward the other, in an upward

direction, said slope of each panel being at an angle of
between 2° and 10° to the vertical, each of said panels having
retroreflectant material covering a substantial area thereof,
wherein said panels are formed of aluminum and said retroreflectant
material is a layer attached to the outwardly facing
surface of each panel.
15. Marker for assisting the landing of a fixed wing
aircraft or helicopter, comprising a pair of substantially
planar panels facing approximately away from each other
and each sloping toward the other at a convergence angle of
between 4° to 20° and having retroreflectant material covering
a substantial area of each of said panels wherein said panels
are formed of aluminum and said retroreflectant material is
a layer attached to the outwardly facing surface of each panel.
16. In combination, an aircraft runway, a marker therefor,
and a support surface for said marker,
means for mounting said marker on said support
surface in a predetermined attitude,
said marker, when so mounted, comprising a pair
of panels facing approximately away from each other, said panel
with said marker in said predetermined attitude, sloping
upwardly toward each other,and each sloping at an angle of
between 2° and 10° to the vertical, each panel having retroreflectant
material covering a substantial area thereof,
wherein said panels are formed of aluminum and
said retroreflectant material is a layer attached to the out-wardly
facing surface of each panel.

17. Marker as claimed in claim 13 wherein, in said
attitude, each said panel slopes at an angle of 2° to 6° to
the vertical.
18. Marker as claimed in claim 14 wherein, in said
attitude, each said panel slopes at an angle of 2° to 6° to
the vertical.
19. Marker as claimed in claim 15 wherein said
convergence angle is 4° to 12°.
20. A combination as claimed in claim 16 wherein, in
said attitude, each said panel slopes at an angle of 2° to 6°
to the vertical.
21. Marker as claimed in claim 13 wherein, in said
attitude, each said panel slopes at an angle of 8° to 10° to
the vertical.
22. Marker as claimed in claim 14 wherein, in said
attitude, each said panel slopes at an angle of 8° to 10° to
the vertical.
23. Marker as claimed in claim 15 wherein said
convergence angle is 16° to 20°.
24. In combination as claimed in claim 16 wherein, in
said attitude, each of said panels slopes at an angle of
between 8° and 10° to the vertical.
25. Marker for support on a support surface in a
predetermined attitude, of a size to be visible to a pilot
on a descent path, comprising a pair of substantially planar
panels facing approximately opposite directions and, in said
attitude to each slope toward the other, in an upward direction,

said slope of each panel being at an angle of between 2° and 10°
to the vertical, each of said panels having retroreflectant
material covering a substantial area thereof, wherein said
panels, when considered in plan, converge from one end toward
the other to provide a toed-in effect.
26. Marker for assisting the landing of a fixed wing
aircraft or helicopter, designed for support on a support
surface in a predetermined attitude, comprising a pair of
substantially planar panels facing approximately opposite
directions, and, to each slope toward the other, in an upward
direction, said slope of each panel being at an angle of
between 2° and 10° to the vertical, each of said panels having
retroreflectant material covering a substantial area thereof,
wherein said panels, when considered in plan, converge from
one end toward the other to provide a toed-in effect.
27. Marker for assisting the landing of a fixed wing
aircraft or helicopter, comprising a pair of substantially
planar panels facing approximately away from each other and
each sloping toward the other at a convergence angle of between
4° and 20° and having retroreflectant material covering a
substantial each of each of said panels,
wherein said panels, when considered in plan,
converge from one end toward the other to provide a toed-in
effect.
28. In combination, an aircraft runway, a marker therefor,
and a support surface for said marker,
means for mounting said marker on said support
surface in a predetermined attitude,

said marker, when so mounted, comprising a pair
of panels facing approximately away from each other, said
panels, with said marker in said predetermined attitude,
sloping upwardly toward each other, and each sloping at an
angle of between 2° and 10° to the vertical, each panel
having retroreflectant material covering a substantial area
thereof,
wherein said panels, when considered in plan,
converge from one end toward the other to provide a toed-in
effect.
29. Marker as claimed in claim 25 wherein, in said
attitude, each said panel slopes at an angle of 2° to 6° to
the vertical.
30. Marker as claimed in claim 26 wherein, in said
attitude, each said panel slopes at an angle of 2° to 6° to
the vertical.
31. Marker as claimed in claim 27 wherein, in said
attitude, each said panel converges in a vertical plane at 4°
to 12°.
32. A combination as claimed in claim 28 wherein,
in said attitude, each said panel slopes at an angle of 2°
to 6° to the vertical.
33. Marker as claimed in claim 13 wherein, in said
attitude, each said panel slopes at an angle of 2° to 6°
to the vertical.
34. Marker as claimed in claim 14 wherein, in said
attitude, each said panel slopes at an angle of 2° to 6° to
the vertical.

35. Marker as claimed in claim 15 wherein, in said
attitude, each said panel converges in a vertical plane at
4° to 12°.
36. A combination as claimed in claim 16 wherein, in
said attitude, each said panel slopes at an angle of 2° to
6° to the vertical.
37. Marker as claimed in claim 29 where said convergence
in plan is between 0° and 3°.
38. Marker as claimed in claim 30 where said
convergence in plan is between 0° and 3°.
39. Marker as claimed in claim 31 where said convergence
in plan is between 0° and 3°.
40. A combination as claimed in claim 32 where said
convergence is between 0° and 3°.
41. A marker as claimed in claim 1 wherein said marker
is frangibly supported on said support surface.
42. A marker as claimed in claim 2 wherein said marker
is frangibly supported on said support surface.
43. A marker as claimed in claim 3 wherein said marker
is frangibly supported on said support surface.
44. A combination as claimed in claim 4 wherein said
marker is frangibly supported on said support surface.
45. A marker as claimed in claim 1 wherein said panel
carries a fluorescent stripe which is horizontal in said predetermined
attitude.

46. A marker as claimed in claim 2 wherein said panel carries a fluorescent stripe
which is horizontal in said predetermined attitude.
47. A marker as claimed in claim 3 wherein said panel carries a fluorescent stripe
which is horizontal in said predetermined attitude.
48. A combination as claimed in claim 4 wherein said panel carries a fluorescentstrip which is horizontal in said predetermined attitude.

Description

' CA 02079919 1998-09-14
This invention relates to a marlcer for use in marlcing unlighted runways or
helicopter landing pads in remote areas.
There is a considerable need for a cheap and efficient reflector marlcer for
remote runways which may located in areas without a practically available source of
power. Such a cheap and efficient reflector marlcer may also required as back up, for
use on a normally lighted runway, in case of power failure. There is an analogous need
for helicopter pad marlcers.
The invention provides an economical and efficient runway marlcer for fixed
wing aircraft and helicopters, having means for mounting the marlcer adjacent a
runway in a predetermined attitude. The marlcer has a pair of substantially planar
panels joined to face in approximately opposite directions. ~ach panel extends
upwardly and slopes toward the other and slopes at an angle of about 4~ - 12' tothe other panel, for fixed wing aircraft, whereby the reflector may be mounted in said
attitude with the panels each sloping at 2~ - 6~ to the vertical, a substantial part
of each of said surfaces being reflectant. (For helicopters the panels will converge at
16~ - 20 and slope at 8~ - 10~ to the vertical when in the desired attitude).

CA 02079919 1998-09-14
By retroreflection herein is meant reflection back toward the source of the
incident ray.
There is thus provided a convenient runway marlcer which may be used in a
series of spaced locations on each side of the runway, with the planar reflectant
surfaces at 2~ - 6~ to the vertical to correspond to the preferred 3" descent angle for
fixed wing aircraft, and with the normals to the planar surfaces directed in a vertical
plane parallel to the runway; so that a plane on a landing approach with its landing
lights or a spotlight on, will receive the brightest retroreflection when descending in
line with the runway and at an 2~ - 6 descending approach path. Since reflectantsurfaces of specific qualities are discussed hereafter, it is noted that an ordinary
reflectant surface will give (to the pilot) a higher retroreflection when the beam is
incident normal to the reflecting surface, than when the beam's direction of incidence
is non-normal.
In a preferred aspect of the invention, the reflectant area is covered with
~rolenecting material which gives a brighter re~lorenection for incident light normal
to the plane of the reflector than its l~llul~nection for light incident at another angle.
Thus r~llorenecting rnaterial and normally reflecting material will give a higher degree
of le~lolenectivity to normally incident light but the relative drop in retroreflectivity
will be greater with

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ordinary than with retroreflective material. Thus for
aircraft approaching the marker from directions other
than normal to a reflectant area, the marker with retro-
reflectant material is easier for the pilot to detect.
With retroreflectant material, the pilot of an
approaching aircraft receives, whatever his approach angle,
a brighter reflection of his landing lights than with an
ordinary reflector, and, because of a quality of the preferred
retroreflector, receives the brightest reflection when he
is on the correct approach path. Thus the pilot may use
the reflection intensity as his guide toward finding and
following the correct path.
In a preferred aspect of the invention the panels
carrying the reflectant material, (and preferably the whole
marker (other than the reflecting layers)) are made of
aluminum. Although many of the advantages of aluminum are
well known, a particular advantage with this invention is
that aluminum has nearly the same coefficient of thermal
expansion as the preferred retroreflectant material which
is preferably applied as a layer to the panel. Considering
the fact that the reflector in accord with the invention
should be designed to withstand a temperature range of -40~C
to +50~C, the effects of differential thermal expansion
between the body of the reflector and the reflectant surface
are material and in many situations, the use of aluminum or
aluminum alloys is found the best way to avoid buckling or

r~
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tearing of the retroreflectant material, since the thermal
expansion coefficient of aluminum or aluminum alloys is
close to that of the preferred retroreflectant material.
By 'aluminum' hereafter, including the claims, I
mean to include aluminum alloys.
In a preferred aspect of the invention there is,
on each panel, in addition to the retroreflectant area, at
least one stripe (and preferably two) of fluorescent material
designed to give a significant daytime indication to the
pilot of the presence and (considering a number of markers
collectively) of the direction of the runway, it being
understood that the retroreflectant material tends to give
a flat impression, not easily noticeable by the pilot when
~ illuminated by sunlight (except when the pilot is) or daylight.
In a preferred embodiment of the invention each of
the planar panels is formed of a sheet of material, preferably
aluminum, where the panel integrally extends into side walls
generally perpendicular to said panels, and means are
provided for joining each side wall of a panel to the adjacent
side wall of the opposite panel. Preferably each panel side
wall will be provided with a inwardly directed flange at its
inner end generally perpendicular to the side wall and (at
the desired relative angles of the panels) parallel to the
flange on the side wall to which it is to be joined. Thus
each flange of one side wall of one panel may simply bolted
or other~ise attached to the flange of the appropriate side

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wall of the other panel, to produce the body of the
reflector.
In a preferred form of the invention the planar
panels, in addition to converging upwardly toward each
other also converge in plan from one end toward the other
to provide a toed-in effect. Thus vertical planes through
the respective panels intersect at an angle of greater
than O and less than 3~. The result is that the toed-in
markers may be arranged on each side of the runway and will
give a brighter retroreflection to a pilot descending along
a line centered over the runway than with markers where the
vertical planes through the marker panels were parallel.
The body of the marker thus produced may be provided
~ with anchoring means, and, if desired, a top member. The
anchoring means may of any design, adapted to provide the
correct azimuthal orientation of the marker and to provide
the correct attitude implying correct slope of the panel
sides. Preferably I provide a base plate with side flanges
which attach to lower portions of the side walls of the
joined body. The base plate may then be mounted on the
ground surface beside the runway or on the runway by such
means as spikes inserted into the surface or by bolting
to a pre-installed base. Shims may be used with the spikes
or bolts to achieve the correct attitude and in addition
the marker must be installed in the correct azimuthal
orientation.

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'_
In drawings which illustrate a preferred embodiment
of the invention:
Figure 1 shows inventive markers marking a runway,
Figure 2 shows an assembled marker,
Figure 3 shows the marker of Figure 2 in exploded
view,
Figure 4 shows a broken-away view of an assembled
marker,
Figure 5 shows an alternative construction for
the marker base.
Figure 6-8 show preferred retroreflectant material
Figure 9 shows a modified form of the inventive
marker
Figure 10 shows a runway marked with the marker of
Figure 9; and
Figure 11 shows a frangible mount for the marker.
In the preferred embodiment of the invention:
Figure 1 shows a runway for fixed wing aircraft
marked with 6 markers 10 in accord with the invention
arranged three on each side of the runway in respectively
spaced locations. Each marker has a pair of outwardly facing
reflecting panels 12 converging upwardly with (in correct
attitude) a slope to the vertical of 2~ - 6~ and, in
azimuth, oriented so that a vertical plane parallel to the
longitudinal direction of the runway is perpendicular to
the planes of the reflecting surfaces of the panels.

2 ~ 7~
Each marker has two planar panels 12. In the
preferred construction each panel extends integrally on
each side into side walls 14 preferably generally perp-
endicular to the panels and extending along their height.
The side walls are each provided with inwardly turned flanges
16 perpendicular to the side walls and arranged so that
the flange 16 of the side wall of one panel may be parallel
to and juxtaposed to the flange 16 of the appropriate side
wall of the other panel. Registering bolt holes 18 are
provided in the flanges so that each abutting pair of flanges
may be bolted together to form the completed marker body.
The panels 10 and side walls 14 are made of aluminum thick
enough to be self sustaining.
The body, as shown is preferably provided with a
base plate 18~for mounting the panel. The base plate 18 is
preferably made of aluminum, thick enough to be self
sustaining and dimensioned to conform to the area defined
by the opposed lower edges of the panels and the opposed
lower edges of respective pairs of joined side walls.
The base is provided with upstanding flanges 20 at opposed
edges selected to overlie the outer surfaces of the side
walls for attachment thereto, preferably, where aluminum
is used, by self tapping screws 22. The base plate is
preferably provided with apertures 24 for anchoring means.
In Figure 3 the mode of attachment for anchoring is by
spikes 26. The azimuthal orientation of the marker must

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be selected so that vertical planes through the planar
panels are aligned with the runway. The attitude of
the marker to ensure the correct angle of the panels to
the vertical is then adjusted by the use of appropriately
selected shims 28 in the form of washers about selected
spikes. In Figure 5 the base plate is provided with a
bolt hole 24B and an arcuate slot 24A about the bolt hole
for receiving bolts 30 from a poured concrete base. The
arcuate slot allows orientation of the marker to achieve
the desired azimuthal orientation and shims 28A may be
used about ~he of the bolts to achieve the desired attitude.
The levelling of a marker in its correct attitude may
however be performed by other or more sophisticated methods
than those shown.
The marker may be provided with a top plate 34
having four side flanges 36 adapted to overlie the top
edges of the panels 10 and side walls 14. The top plate
may be attached by self tapping screws 40 through registering
apertures 38 and 42.
Top plate 34 and base 18 may also be made of
self-sustaining aluminum. Top plate 34 and base 18 may
each be provided with an aperture 44 ( the apertures are
vertically aligned) to receive the standard of a marker
flag.
- The panels 10 will, over most of their area be
covered with retroreflecting material 46. I prefer to use

CA 02079919 1998-09-14
a plastic provided with an aluminized coating defining an array of recessed cubecorners. Such a le~rolcnecting material will form relatively wide angles to the normal,
re-~o~cnectant light from the landing lights (or searchlight) of a descending aircraft.
However such retroreflector has a further quality of importance in the preferred form
of the invention. The retroreflection at large angles to the normal, of the preferred
recessed cube corner reflector is relatively good but retroreflection is strongest when
the incident (and hence the reflected) beam are normal to the surface. Thus the pilot,
of a descending aircraft may tell when he is on the correct descent path by the fact
that the rc~ cnection from a panel becomes brighter or less bright as he approaches
or departs from the descent angle normal to the panel.
I prefer to use a cube corner recessed retroreflector formed of plastic with thecube corner recesses molded in a selectively colored aluminized reflector coating on
the outer cube surface. In the preferred form of such material the recessed cubesurfaces are covered with a protective transparent smooth layer (not shown) also of
plastic to protect and lceep clean the recessed cube.
As the retroreflectant material I prefer to use surfaces made up of the cube
corner reflectors as described in the following IJ.S. Patents;

2, 380, 447 Jungerson
3, 712, 706 Stamm
3, 684, 348 Rowland
3, 810, 804 Rowland
4, 025, 159
4, 202, 600 Burke
The teachings of the above patents are incorporated
herein by reference.
In particular the invention preferably makes use
of cube corner reflective sheeting as described in the
Burke patent 4, 202, 600 where regular arrays of cube
corner reflectors in sheets are arranged in zones (in-
distinguishable to the user) oriented relative to adjacent
zones in such a way that retroreflective intensity
variation with azimuthal angle (measured in the plane of
the sheet), is reduced at high angles of incidence to the
normal to the sheet.
By an array is meant an ordered group of cube
corner triads. A 'zone' is the area occupied by such an
array.
The invention takes advantage of the fact that
retroreflectant material composed of arrays of cube corner
reflectors (which are not individually distinguishable at
minimum expected viewing distances) customarily retroreflect
inciden~ light more strongly at a normal angle of incidence
-10-

~ ~ Q 7~ ; 3
than at any other angle of incidence.
It is noted that with all cube corner reflector
arrays there is some directivity in the strength of the
secondary reflection. That is for a given array zone
the secondary reflection will be stronger in some azimuthal
directions relative to the normal than other. This is of
course more noticeable with a single array where all triads
have an ordered orientation relative to each other. It will
also be noted that the cube corner reflector array zones
which are taught by Patent 4, 202, 600 and preferred for
use with the invention, are too small for resolution by
the viewer so that the actual orientation of individual
zones of the reflecting surface is not known when a sheet
bearing the reflectant coating is applied. Thus it is
preferable if the cube corner reflector sheet is divided
into zones (indistinguishable at usual viewing distances)
which are differently oriented relative to each other tending
to give a more uniform reflection at large angles to the
normal and at varying azimuthal angles about the normal.
Preferably the cube corner cavity material is
that sold under the trade mark REFLEXITE, a product of
the Reflexite Corporation of New Britain, Connecticut.
In such product the cube corner cavities are arranged in
windows formed by triads of mutually perpendicular cube
faces in an ordered array with a predetermined orientation.

Such ordered arrays are in zones small enough to be
indistinguishable to the viewer at minimum normal
viewing distances. The zones are preferably arranged
to have two orientations at 90~ to each other arranged
in a checkerboard or other pattern. The REFLEXITE
material customarily is supplied in rolls with a self
adherent backing.
Figures 6-8 are taken from U.S. Patent 2,202,600
previously referred to. In Figure 6 the preferred retro-
reflective sheeting is schematically illustrated from the
non-retroreflecting side. The array as oriented in Figure
6 may be thought of as having an orientation corresponding
to a horizontal directional arrow. As stated in Patent
4,202,600 the orientation of an array with an orientation
as shown in Figure 6 can be varied in a regularly alternating
pattern, such as a checkerboard pattern, in a random pattern
or in any other pattern that provides sufficient mixing
of different orientations to give the sheet an appearance
of uniform brightness when viewed at a high angle of
incidence from the minimum.
Figures 7 and 8 show two preferred methods of
combining arrays in zones with orientations at 90~ to each
other. Since the arrays have 60~ symmetry (90~ - 60~ = 30~)
each zone has its cube corner reflectors oriented at 30~
to adjacent zones. The result is reflective sheeting which
for retroreflected rays at 60~ to the normal, has relatively

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even reflectivity at different azimuthal angles about the
normal.
As previously stated the preferred sheeting of
the Reflexite Corporation of New Britain Connecticut. The
zones are indistinguishable at normal minimum viewing
distance.
It is noted that the two qualities of the preferred
material which are of principal value with this invention,
are that the night retroreflection at relatively wide angles
to the normal to the plane allows the pilot, at night, to
find the general location of the runway and its markers,
while the stronger retroreflection when the pilot is on
his correct descent path acts as an indicator to help him
to reach and maintain the correct descent path.
The preferred retroreflecting material is
customarily supplied in rolls, from which the may be cut
Lor adhesive application to panels 10 to form, as shaped
by the planar panels, a substantial planar retroreflecting
area 46. Such area will be principally used at night and
I prefer to use retroreflecting material of silver color.
Since the marker should be designed to operate
over a temperature range of -50~ to 40~C, it is of some
importance that the thermal expansion coefficient of the
retroreflectant layer be close to that of the panels 10.

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With the preferred retroreflecting material as described
above the planar panel is preferably made of aluminum
since its coefficient of thermal expansion is sufficiently
close to that of the preferred "Reflexite" as to prevent,
in most circumstances, the buckling or tearing of the
'Reflexite' over the above temperature range.
In this embodiment it is preferred to make the
marker other than the reflecting layer or layers of a
single piece of aluminum sheet, of sufficient thickness
to sustain its shape and bent to form the panels 10, side
walls 14 and flanges 16 as described.
Although the retroreflectant material works
excellently at night when illuminated by the searchlight
or landing light of an aircraft, such material is difficult
to distinguish in sunlight or ambient daylight which, of
course, is not normally retroreflected to the pilot.
Accordingly, it is preferred to provide at least one and
preferably upper and lower stripes 48 of fluorescent
material, above and below each area 10 and oriented to
be horizontal in the preferred attitude of the marker. Such
bars are preferably formed of self-adhesive fluorescent
tape of color contrasting with that of area 46 (fluorescent
orange is preferred for stripes 48) and overlying each
panel 10 above and below each area 46 (as shown) and
alternatively the material forming area 46 may be cut to
cover the whole area of panel 10, and the upper and lower

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fluorescent stripes 48 placed thereover.
There is thus provided, for daytime use, the
marker with two horizontal stripes 48 which assist the
pilot in locating the runway, and its azimuthal orientation,
and to indicate horizontal indications in directions
transverse to the runway. The bars 48 of course do not
strongly retroreflect nor do they give the pilot an
indication of whether he is descending at the correct
angle. They are however useful in the daytime when the
retroreflectant material looks dull under solar or ambient
light illumination.
The embodiment of Figure 5 shows a poured concrete
base 50 which would be located beside the runway and which
has a pair of upstanding bolts 30. The base 18A is rotated
about the bolt through hole 24B until the correct azimuthal
orientation is obtained, and then the nuts 52 are tightened
to fix the tray firmly in place. The marker is then
installed on the tray as described in connection with
Figure 3 and 4.
It should be said that any method of anchoring
and levelling is within the scope of the invention.
The preferred embodiment has been described with
angular slope of the panels 10 suitable for fixed wing
aircraft. This is believed to be the principal use of
the invention.

CA 02079919 1998-09-14
However the inver~tion rnay also be used to mark helicopter pads and launching
areas. For use with helicopters, the panels 10 and their re~lore~lective material should
converge at 16~ - 20~ and, in the correct marlcer attitude slope at 8~ - 10~ to the
vertical, corresponding to the desired helicopter descent angle. The panels will, in
use, be oriented to be perpendicular to a vertical plane extending in the desired
azimuthal approach direction.
Figure 9 shows a form 11 of the marlcer which is a modified alternative to that
shown in Figure 2. Figure 9 shows that the members lOA, 14A, 34A (corresponding
in function to members 10, 14 and 34 are so proportioned that opposite faces of the
planar panel slope toward each other at an angle A to the vertical as with the panel
of Figure 2. Thus for Figure 9 (or Figure 2) the angle A is 2~ - 6~ for fixed wing
aircraft and 8c 10'' for helicopters. Figure 9 further shows that it is preferred to
have the planar panels 'toed-in' toward each other by the angle B (malcing the angle
of convergence 2B). For most applications B will equal about 1~ . Although such
convergence. is best shown only at the top of the marlcer, the planar panels arearranged so that they converge at substantially the same angle in any horizontalsection through the marlcer. Figure 10 shows, in plan, a plurality of the marlcers of
Figure 9. The advantage of the toed-in arrangement will be obvious from Figure 10.
Thus, as shown, the toed-in is achieved by orienting the planar panels so that vertical
planes perpendicular to the panels intersect at an angle of greater than 0~ and less
than 3. Thus as shown
- 1 6-

~ Q 7 ~
the toed-in markers will tend to self retro-reflect from
each side of the runway toward an aircraft approaching
along the center of the runway axis, more clearly than
would markers as in Figure 2 where the vertical planes,
normal to the planar panels are parallel to each other.
Thus in the alternative of Figures 9 and 10
the toed-in planar panels lOA are provided with central
retroreflecting layers 46 bordered by upper and lower
fluorescent stripes 48 as in the embodiment of Figures
2 and 3.
Figure 9 also illustrates the provision of a
marker pennant 66 on a standard 68 which passes through
upper aperture 44 to seat on a spring 70 which rests in
lower aperture 44.
Figure 11 demonstrates that the reflecting marker
constructed as described in relation to either Figure 2
or Figure 9 may be mounted on a frangible standard 60 of
plastic which is molded to provide an easily frangible
narrowing 62. The Frangible standard is mounted in a
base 64 in any conventional manner while the base may be
embedded in the ground beside a runway or may be free
standing. The provision of the frangible mount means that,
if a marker is struck by an errant aircraft, it may break
off with less damage to the aircraft than would a fixed
- marker.

~ 7~
'~_
The various embodiments show retroreflecting
material 46 on the two sloping sides 10 bordered by
upper and lower fluorescent strips 48. It is understood
that, if desired, end walls 14 or 14A may be provided with
a similar arrangement having a central area of retro-
reflectant material similar to material 46 bordered by
upper and lower stripes of fluorescent material similar
to strips 48.
Figure 10 indicates, in dotted form, that
markers 11 maybearrayed across each end of the runway,
to indicate the runway limits.

Representative Drawing