Note: Descriptions are shown in the official language in which they were submitted.
107174~
This invention relates to a light system for guidance of aircraft and
more particularly a visual ligh~ system by which the approach of an aircrsft to
a runway is guided and the flare-out and touch down of the aircraft to the run-
way is precisely guided.
Aircraft guidance lighting systems are presently being used in many
airports and operate to a degree of satisfaction to prov~de a pilot with guid-
ance during the approach segment of a landing when visibility conditions are
good. However, in low visibility conditions, deficiencies occur in the present
approach lighting systems in that they will provide a pilot with horizontal and
roll guidance but do not provide him with vertical guidance. Also, in low
visibility conditions and possibly in good visibility conditions, while the
present approach lighting system will guide the pilot during the approach
segment of his landing path to the runway threshold, present systems fail to
provide adequate guidance during the landing segment to guide the pilot during
flare-out and touch down.
An object of the present invention is to provide an aircraft guidance
system for providing guidance visible to a pilot during both the ~pproach seg-
ment and landing segment of the aircraft when approaching and landing on a
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runway.
In the approach segment of the landing path, the indicating lights
provide vertical and pitch guidance as well as horizontal and roll guidance for
virtually eliminating missed approaches and danger of undershooting the runway
due to a pilot's inability to visually determine his vertical position. This
is attained by a system of lighted indicators oriented on or near the ground
which define two plane surfaces, the intersection of which is a straight line
which is precisely the correct path for the aircraft to follow in making its
approach to the runway. The indicators are arranged in a manner to form lines
which appear to the pilot to converge at the correct point of the runway even
though that point on the runway and the runway itself is not yet visible. In
the flare and landing segment of the landing path, the pilot receives guidance
from the runway threshold to which he has been properly guided by the approach
segment. At this point, the landing path changes from a slope of about 3 to
a flare-out and very flat descent of about 1 until the wheels of the aircraft
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touch down on the runway. This guidance during the flare-out
and touch down segment is provided by indicator units oriented
at predetermined spaced intervals along at least one side or
both sides of the runway positioned and configured to define a
number of plane surfaces each of which intersect a longitudinal
vertical plane passing through the runway center line so as to
form or define the precise landing path of the pilot's eyes so
that the indicators would all show as being aligned when the
:` aircraft is on correct landing path but their slopes would vary
by becoming flatter as they are placed further down the runway
with the intersections of all of the imaginary plane surfaces
~" with the ground being lines which converge at a point on the
;` runway where the landing path line touches the runway.
It is another object of the invention to provide a visual
light system for providing guidance to aircarft pilots during
. both an approach segment and a landing segment of a landing path
for the aircraft to enable accurate and precise visual guidance
for the aircraft pilot in which the system is relatively in~
expensive and materially enhances the capability of a pilot to
safely land an aircraft even in periods of very low visibility.
The invention relates to a visual approach guidance
system for guiding an aircraft toward an aiming point on a run-
way comprising a plurality of indicating light units spaced
equally on each side of the correct approach path for the air-
craft with the light units converging toward the aiming point,
each of the light units including at least two light members
oriented in laterally and vertically spaced relation with the
inner light members being above the outer light members, the
outer light members being in the form of a longitudinal light bar
and the inner light members being a dot-type light for direct
viewing of the bars from the approach path as closely spaced
solid line segments in longitudinal alignment and converging
toward the aiming point and direct viewing of the dot-type
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lights from the approach path as being in alignment with the bars, -
a vertical plane including the dot-type lights in a pair of light
units disposed in transversely aligned relation on opposite
sides of the correct approach path for the aircraft and being
defined by a base line extending between the outer light mem-
bers and sides extending from the outer light members through
- the dot-type light ~embers having its apex coinciding with the
approach path of an aircraft whereby the pilot of an aircraft
following the approach path will observe two converging seg-
mental lines of light with the dot-type lights being aligned
.;. with the light bars, an inclined triangular plane surface being
defined by the approach path extending to the aiming point, the "
outer light members along one side of the approach path extend-
ing to the aiming point and a base.line extending from an outer
light member along said one side of the approach path and through
a corresponding inner light member to the approach path with the
aiming point defining the apex of the inclined triangular surface,
and a guidance system for guiding an aircraft during the flare
out and touchdown portion of the approach path in which the touch-
2~ down point is longitudinally inwardly on the runway from the
aiming point, said guidance system for the flare out portion
including a plurality of indicating light units spaced along
the runway and converging toward the touchdown point, each in-
dicating light unit in the guidance system for the flare out por-
tion of the approach path including three elongated bars with two
of said bars in longitudinal alignment with each other and the
third bar di8posed in spaced parallel relation thereto and cen-
trally between said two of the bars for direct viewing of the
bars themselves as closely spaced solid line segments in apparent
longitudinal alignment with each other while following the flare
out portion of the approach path toward the touchdown point.
Figure 1 is a perspective view of the approach segmer.t of
the light system of the present invention illustrating the line of
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intersection of two plane surfaces formed by the lighting system.
Figure 2 is a top plan view of the assembly of Fig. 1.
Figure 3 is a vertical elevational view of the assembly
of Figs. 1 and 2 illustrating the intersecting relationship of
.'5' the two plane surfaces.
Figure 4 i9 a diagrammatic view illustrating the light
system of the present invention indicating a correct path and
- incorrect path.
Figure 5 is a perspective view of the landing segment of
the flight path.
Figure 6 is a top plan view of the assembly of Fig. 5.
Figure 7 is an end elevational view of the assembly of -
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Fig. 5 illustrating the plane intersections.
Figure 8 is a diagrammatic view showing a correct flight
path and incorrect flight path.
Referring now to the drawings, an airport runway is
designated by
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reference numeral 10 with the landing aircraft being designated by numeral 12. r
The light system of thi~ invention is divided into two segments with the
;1, approach segment being illustrated in Figs. 1-4 and the landing segment being
illustrated in Figs. 5-8 with the pilot using the approach segment for guidance
to the threshold 14 and an aiming point 16 spaced from the threshold 14 of the
runway 10 and the pilot using the landing segment for the flare-out and flat
rate of descent to a touch down point 18 on the runway 10.
~ The approach segment includes two rows of light bars 20 and 22 which
;g' converge and intersect at the aiming point 16 as illustrated in Fig. 2. Located
10 inwardly of and above the rows of light bars 20 and 22 is a pair of rows of
lights 24 and 26 which may be in the form of rou~d light dots which also con-
verge to the aiming point 16 und which are located inwurdly of and above the
horizontal plane of the light bars 20 and 22 as illustrated in Pigs. 1 and 3.
The two plane surfaces 28 and 30 illustrated in Fig. 3 are de~ined by a surface
passing through the lights 24 and 20 on one side and the lights 26 and 22 on
the other side so that the point of intersection of the plane surfaces 28 and
30 form a precise approach path 32 for the aircraft 12 as illustrated in Figs.
1 and 2 ~o that the aircraft will be in the appropriate approach path in align-
ment with the center of the runway and in the appropriate slope toward the aim-
20 ing point 16 of the runway 10.
The pilot's eye will see an arrangement illustrated in the upper -`-
diagramm~tic illustration in Fig. 4 when he is on the proper approach path 32.
The other three illustrations in Fig. 4 will indicate to the pilot that he is
not on the correct approach path and will indicate to him what must be done to
correct his approach path so that the aircraft 12 will precisely follow the
approach path 32 defined by the intersectio~ of the two plane surfaces 28 and
30.
With the approach lights defining the approach path 32, the pilot will
be provided with a target towards which the aircraf~ is to be aimed for landing
30 at the correct point on the runway and provides the pilot with precise hori-
zontal and verticsl guidance for putting and keeping the aircraft on a correct
approach path even when only a segment of the approach lights are visible due
to rain~ fog or other conditions causing low vislbility. The intersection of
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the two plane surfaces is a straight line 32 which is the precise ~orrect path
for the aircraft to follow in making its approach to the runway with the indi-
cators forming lines which to the pilot converge at the correct point of the
runway even though that point or the runway itself is not yet visible. When
~;, the pilot's line of sight is on either plane surface, the lights defining that
surface will form a straight line or segments lying in a straight line since the
indicator lights are also situated as to be in that plane. The rows of lights
should be distinctly different from each other so that when the pilot's eye is
~; above the plane, he would see two distinct rows of lights and if the pilot's
eyes are too low, the rows would be reversed. The closer the aircraft and
pilot's eye i8 to being in the plane surface, the closer the rows will become
and will merge into a single row when right on the plane surface. The light
rows could be distinctly colored and provided with a slot srrangement so that
the pilot could only see the light when on the plane surface and if above the
plane surface, the light would disappear or the light could be made to change
color when above the surface such as appearing yellow and if below the plane,
the light could also disappear or change color and because of the danger element
~hould be made to change to red. Other arrangements could be provided in order
to provide guidance to the pilot. The warning feature whereby all or some of
2Q the lights change to red for low approach positions is desirable regardless of
how the plane surface is indicated to the pilot. While this portion of the
invention relates primarily to the approach to the runway in its final stages,
approximately 3,000 to 4,000 feet from the threshold, it may also provide en- -
route guidance or check points. For example, rows of lights on or near the
ground, or water surface, can define the plane surfaces and hence the correct
path of the aircraft going through mountain passes or the like where the airport
is not visible until the pass has been traversed but is near enough that cor-
rect altitude for a good approach to the runway is important. Also, the cor-
r~ct approach slope can be defined by a plurality of intersecting and defined
plane surfaces wherever this might be to advantage. For example, where there
- is a deep drop off in the runway approach and the land contours favor two or
more pairs of defined planes, all having a co n line of intersection.
The landing segment of the flight path illustrated in Figs. 5-8
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provides a continuation of the approach segment of the flight path with the
aircraft following the approach line 32 to the runway threshold. At this
point, the pilot looks to the landing segment for flare-out and guidance to
actual touch down.
The guide slope or approach path to the threshold and perhaps slightly
down the runway toward the landing point 16 is about 3 above horizontal. Then
r~ the path changes to a flare-out and very flat descent about 1 above horizontal
; until the wheels of the aircraft touch down on the runway pavement. The land-
ing segment of the system defines the flare-out and the resulting flat descent.
The landing segment includes indicating light units 34, 36, 30, 40
and 42 with each light uni~ being in the form of three bar lights or any other
lights of suitable configuration with the lights being oriented on one or both
sides of the runway 10. If light units are mounted on both sides of the run-
way, they must match each other with the bracketed portion of the lights gener-
ally designated by numeral 44 in the right-hand portion of Fig. 6 indicating
another type of light assembly in the form of longitud~nally extending bars
with dot type lights associated therewith. As indicated, the indicating units
34-42 are disposed at predetermined spaced intervals and are so positioned and
configured to define a number of plane surfaces each of which intersect a
longitudinal vertical plane passing through the runway cen~er line so as to
form or define the precise landing path 46 of the pilot's eyes. Probably three
of these planes would suffice if a varying distance of the indicators from the
- runway i8 acceptable as illustrated but in some instances, it may be preferable
to keep all of the indicator units the same distance from the runway edge with
it being essential that the indicators be spaced longitudinally close enough
that even in fog, two or more could be seen a~ once thus requiring a correspond-
ing number of plane surfaces. The indicator units would all show as being
aligned when the aircraft i5 on a correct landing path as illustrated in Fig.
~ but their slopes would vary, becoming flatter as they are placed further
down the runway as illustrated in Fig. 7. It is pointed ou~ that the inter-
section of all of the imaginary plane surfaces with the ground are lines wh~ch
all converge at a point on the runway where the landing path line 46 touches
the runway 10 which is indicated at the touch down point 18.
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As illustrated, the indicating units 34 are placet in plsne ABC thus
defining line BCE which corresponds with the approach path 32. As the pilot's
eye picks up the indicating units 34, 36, 38, 40 and 42, the unit 34 is indi-
cating the approach path and when the pllot's eye no longer observes the indi-
cating unit 34, the indicating units 36, 38, 40 and 42 will guide the pilot on
the landing path 46. During the landing segment, the runway edge lights or
runway center 11ne lights have become visible or at least a part of them have
; become visible so that the pilot has horizontal guidance from them and thus
will be over the center line of the runway and will automatically be at correct
;~ 10 height and rate of descent for landing and touch down if he keeps the indicator
lights aligned. If the indicator lights are used on both sides of the runway,
the plane surfaces they define as designated by numerals 48 and 50 in Fig. 7
provide the intersection which is the landing path 46 but because these imagi-
nary planes become progressively flatter, the intersection becomes subject to
increasing horizontal error and therefore reliance should be placed on the
conventionsl runway lights or center line lights for horizontal control.
Because horizontal guidance is available over the runway, the guidance as to
the height need only be given periodically since no aiming effect need be
derived from the indicator ligh~s as a group. Therefore, the indicator lights
can be in the form of clusters of lights, three bars to be aligned as illus-
trated, two dots and a bar, two bars and a dotl a triangular configuration
showing as a line when on course and triangular otherwise or any other suitable
configuration. Also color differences of lights may be used or this purpose.
In the landing segment, it probably is not necessary to incorporate a red danger
feature for being too low since the runway is just below and a relatively flat
path of descent has already been achieved. Also, it is prefersble to color
differentiate the approach light units from the landing segment units with the
lighting intensity for the landing segment lights also being less with fog
penetration being determined more by reduced spacing than by light intensity.
When the indicator light units in the landing segment form a line
parallel to the runwsy with a fixed offset distance, the plur~lity of triangu-
lar plane surfaces such as 48 and 50 at esch light unit would have the indi-
cators in the corners of the plane triangles with each group of indicators
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being equally spaced from the runway but the height of the triangular plane
surface at each group of indicators being progressively less so that the height
of each vertical ~riangular surface will terminate at itS upper end on the
landing path 46.
Thus, with the approach segment and landing segment of the flight
path being indica~ed by the indicating light units, the pilot is provided with
a continuous and precise guidance along the approach path with the indicating
units not only indicating to the pilot whether he is on course or off course
but also indicating to him the direction which he is off course and the degree
that he is off course in order to enable proper correction of the deviation so
that the aircraft 12 will proceed on the approach path 32. When he approaches
the landing path segment 46 of a flight path, the pilot~s eyes will pick up
the indicating units in the landing path segment so that he will flatten his
rate of descent and properly flare-out his landing path to the touch down
point 18 by following the guidance pro~ided by the light indicating units in
the landing segment.
