Note: Descriptions are shown in the official language in which they were submitted.
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'l~hi~ ,inv~ntion ~cncrally relates to a visunl npproach and landinp,
system for aircraft having su~)plement<lry warning and indicating device~
associated therewi.th to v$sually guide a pilot in his approach to a runway
and to warn the yi].ot if llis descent path is too low.
Visual indicating systems for guiding pilots during their approach
to runways have been provided and are effective to some degree. Such devices
are frequently rather complex and costly and fail to provide sufficient
warning to a pilot that tlle approach path is too low and such devices also
fail to provide proper guidance when using a two-segment approach for noise
control in which the outer segment of the approach is steeper than the inner
segment or near segment which is a more shallow approach so that appropriate
flare-out and touchdown may be attained.
The following U.S. patents disclose various developments in
landing guidance systems which are somewhat related to this invention.
1,349,277 2,991,743
2,280,126 3,204,218
2,455,721 3,259,985
2,634,399 3,320,584
2,691,150 3,447,128
2,784,925 3,474,406
An object of the present invention is to provide a visual approach
slope indicator for aircraft as disclosed in my U.S. patent No. 3,868,778, ,
combined with a warning device to indicate to a pilot that his approach is
low and therefore dangerous so that he may take corrective action to return
to the proper approach path. The warning device may be in the form of a
red signal light or lights aimed in the direction of a low approach and so
shielded that the red light could only be seen when an aircraft is below.
the proper approach path, in the form of a center bar of light which is
normally white and which will turn red when the approach path drops to a
predetermined degree below the correct path or in the form of a combination
of these two embodiments.
Another object of the invention is to provide a visual approach
filope indicator and landing system including supplementary indicating and warn-
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ing device~ in the form of slgns or symbols which become
visual to the pilot to indicate to tlle pilot that he
should take some action such as a change in course or a
change in the descent path hy looking ahead with such
devices lncluding a red final warning in the event the
pilot fails to change his enroute or approach course at
the appropriate time.
The invention relates to a visual approach
indicator unit including three elongated bars, means
mounting two of the bars in longitudinal alignment with
each other, means mounting the third of the bars in
parallel spaced relation to the two longitudinally aligned
bars and centrally between the two bars, the two bars
being longitudinally spaced from each other a distance
slightly greater than the length of the third bar, visual
means mounted on the bars for direct vlewing of the bars
themselves as closely spaced solid line segments in apparent ~ -
longitudinal alignment with each other while approaching
the same at a predetermined angle perpendicular to the bars,
and warning means associated with the bars for direct -
viewing when approaching the bars at an angle substantially
less than the predetermined angle.
Figure 1 is a schematic side elevational view
illustrating the positioning of the visual approach slope ~'"r
lndicator with a warning device which will warn a pilot
when his approach path to a runway is too low.
Figure 2 is a perspective view of a runway and
slope indicator with red signal lights which are normally
shlelaed asso,ciated therewith which will be revealed eo
the pilot should his approach path be too low.
~igure 3 is a group of views illustrating what is
observed by a pilot under various conditions of approach to
the runway.
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Figure 4 i8 a side view slmilar to Flg. 1 but
lllustratlng an arrangement ln which a center llght bar
will turn from white to red in the event of an approach
being too low.
Figure 5 is a perspective vlew, simllar to Flg. 2,
illustrating this embodiment of the invention.
Figure 6 is a group view, ~imilar to Fig. 3 but
illustrating the warning as it is observed by the pilot
when the embodiment of Figs. 4 and 5 is in use.
Figure 7 is a schematic slde elevational view of
a two-segment approach path in whlch supplementary indicating
or warning devices are employed.
Figures 8-12 are group views illustrating what
is observed by the pilot when a runway or alrport slope
lndlcator ig used in combination with an off runway or off
8 lope indicator.
Figures 13-16 are schematlc slde elevatlonal
views illustratlng varlous arrangements of lights, and shields
and, ln some instances, red llghts or filters ln front of ~ -
whlte lights to provlde a beam of white and/or red llght of
definite configurations with the relative directions of
the beams also being controlled.
Figure 17 is a schematic side elevational view
illustrating sequential arrangements in which the warnlng
or indicating lights are sequenced to
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appesr "off", "on", and "changed to red".
Figure 18 i9 a schematic slde elevational view illustrating sequen-
tial guidance lights in front of a slope indicator.
Figure 19 is a perspective view of the guidance lights of Fig. 18,
the slope indicator and runway observed by the pilot when properly approaching
the runway.
Referring now specifically to Figs. 1-3 an airport runway is sche-
matically illustrated ant designated by reference numeral 20 with a visual
approach slope indicator assembly 22 positioned ad~acent the runway which is in
the form of a pair of horizontally aligned bars 24 that are spaced from each
other and a central bar 26 is positioned between the bar~ 24 but is located
in rearwardly spaced relation from the other two bars 24 to establish a co on
line of sight 28 at a predetermined angle to the ground which designates the
correct approach path having a desired vertical slope so that s8 a pilot observes
the slope indicator 22, he will know that he is on the correct approach path when
the bar 26 is aligned with and between the bars 24 as illustrated in the upper
portion of Fig. 3. This structure and arrangement is the same a8 that disclosed -
~in my aforementioned U.S. patent No. 3,868,778 with the bar~ being illuminated,
brilliantly painted, lighted or otherwise constructed for use during various
visibility conditions. As the center bar 26 becomes disposed either below or
above the bars 24, the pilot will know that his approach is too low or too high.
Inasmuch as the too low condition is re dangerous, the present invention in-
volves the addition of red lights 30 positioned alongside of and below the
bars 24 with an opaque field 32 normslly occluding the lights 30.
The shields 32 would be dull in color or non-brilliant 80 that they
would not be distracting to the pilot. As illustrated in Fig. 3, as the ap-
proach path of the aircraft is only slightly lower than the correct path 28,
the center b&r 26 will be observed as being slightly lower than the two bars 24.
As the degree of error increases and the actual approach path of the aircraft
is lower than would be considered safe, the center bar 26 is not only observed
as being lower than the bars 24 but the red light 30 will become visible with
the intensity of the red lights increasing as the approach path of the aircraft
becomes lower in relation to the correct path. At a predetermined approach path
.. , ., . , ,. . , :
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designated 34, the red lights 30 which may be in the form of red spotlights
will be observed by the pilot but since the shleld 32 is stlll occludlng mo~t
of the light 30, the light 30 will be rather dim or of small intensity. Any
path of movement of the aircraft below the "red line" 34 brings the red light
30 into full view and maximum intensity thereby i~ediately warning the pilot
of a danger condition 90 that he may take correctlve action to pull his air-
craft up to the correct approach path 80 that the center bar 26 becomes aligned
with the bars 24 at which time the shields 32 will again occlude the red light
30.
Figs. 4-6 illustrate a similar arrangement of runway 20 and slope
indicator 22 including the pair of bars 24 snd the bar 26 oriented in the same
manner as in Figs. 1-3. Supported between and below the bars 24 is a tran8-
parent shield 36 which may be of plastic material or the like which is nor-
mally disposed below the center bar 26 when the pilot and aircraft are on the
correct path 28 in which event the pilot observes three white lights 24 and 26
in a row and in alignment with each other as illustrated in the top illustration
of Fig. 6. As the approach path of the aircraft is only slightly lower, the
center white bar 26 will be observed slightly below the two end bars 24. As
the aircraft approaches a path 38 which is too low for proper landing, designated
20 as 38 in Fig. 4, the transparent shield 36 which is red in color will begin to
be aligned with the center bar 26 80 that the center bar or center light 26 will
appear pink in color. If the aircraft i8 on an approach path 40 which is too
low for safe landing because the plane may touch down prior to reaching the
threshold of the runway, the transparent shield 36 will be completely disposed
in front of the white bar 26 so that a red center bar will be observed by the
pilot. The two bottom illustrations in Fig. 6 illustrate the pink transition
condition of the center bar 26 and the red or danger condition thereof which
red line is designated by numeral 40 in Fig. 4. Thus, if a pilot and his air-
craft drops progressively below the correct path 28 where he would see the middle
30 bar as white, he would subsequently see the middle bar as pink, that is a white
and red combination, and then completely red. This embodiment of the invention
operates in subsfantially the same manner as the embodiment in Fig. 1 and any
combination of these two embodiments may be employed and any desirable structure
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may be provided for producing the red light or danger signal to the pllot for
indicating to him that he i8 too far below the proper approach path, thus
indicating to him thQt corrective action should be taken in order to put his
aircraft back on the proper slope or approach to the runway 20.
Figs. 7-12 illustrate a two-segment approach path which i9 now fre-
quently required for noise control which, as illustrated in Fig. 7 includes
an initial steep segment of an approach path designated by numeral 28' which
may be a 6 degree slope and a final approach path 28 which is the same as
the approach path illustrated in Fig. 1 in which a slope indicator 22 is em-
10 ployed in the same manner as in Figs. 1 or 4 either with or without the lowslope path warning device illustrated in Figs. 1 or 4. In this arrangement,
the 6 degree outer segment 28' would be guided by a slope indicator 22'
located at a point spaced from the runway such as a point two mile3 off the
runway in the approach zone with the slope indicator 22' including the same
bars 24 and a center bar 26 oriented to provide a proper 6 degree slope
indication to the pilot of the aircraft following the steep approach path 28'.
The aircraft should gradually change from the steep approach segment 28' of the
approach path to the shallow 3 degree approach segment 28 with supplementary
indicating devices generally designated by numeral 42 indicating to the pilot
20 that he should be going through a transition from the steep se8ment to the low
segment ~ust prior to the point at which such transition is being made. In
Fig. 7 the point A is a condition illustrated in Fig. 8 in which the slope ~ -
indicator 22' indicates to the pilot that he is on the appropriate steep path
28' with the slope indicator 22, of course, indicating that he is too high for ~ -
the shallow segment of the approach path 28. As the aircraft reaches point B
in Fig. 7, as illustrated in Fig. 9, the slope indicator 22' indicates that the
aircraft is on the proper approach path and the slope indicator 22 indicates
that the aircraft is still too high for the approach segment 28. In this con-
dition, the supplementary lndicating device 42 come~ into vicw. The supple-
30 mentary inticating or warning device 42 is in the form of lights, bars or the
like, 44 which may be in the form of a directional control such as an arrow
as illustrated in ~ig. 10 but only the initial lights at the tip of the arrow
are observed when the aircraft is at point B. As the aircraft proceeds along
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the flight path 28', the bsrs 24 and 26 in the slope indicator 22' will remain
in line indicating that the aircraft is properly following the approach path
28' with the warning device 42 indlcating to the pllot that he should malntaln
visual contact and look ahead of the slope indlcator 22' and when the warning
devlce 42 reveals all of the lights 44 as the aircraft reaches point C, the
pilot ~hould then look ahead toward and be gulded by slope indicator 22 whlch
indicates that he is only slightly above the shallow approach path 28 90 that
tbe controls of the aircraft may be properly manipulated for transition from
the steep approach path 28' to the shallow approach path 28 which is the con-
dltion illustrated in Fig. 10. Then, as the alrcraft follows the transitionline from point C to polnt D in Fig. 7, the center bar 26 ln the slope lndlcator
22' properly indicates that the alrcraft 18 too hlgh and the warnlng devlce 42
defined by the lights oriented ln a pattern which illustrates an arrow lndicates
that the pilot should follow the flight path designated by the slope lndlcator
22 which intlcates that the alrcraft ls on the appropriate approach path or the
shallow approach path 28 to runway 20. In the event the aircraft pllot falls ~-
to follow the curved path of transition from the steep path 28' to the shallow
path 28 and continues along a dlrect path to the slope indicator 22' and reaches
point E, each of the lights 44 in the warning device 42 will t~rn red as the
aircraft reaches or approaches point E as illustrated in Fig. 12 80 that the
pilot will be immediately warned that he should take corrective action with the
red arrow also indicating that he should look ahead for guidance from the ~lope
indicator 22 where the pilot will see that the center bar 26 is below the end
bars 24, thus indicating that he should immediately pull the aircraft up so that
it follows approach llne 28, thus avoiding a danger condi~lon. The transition
of the llght 44 from white to red may be accomplished by any of various means
such as that illustrated in Figs. 1, 4 and 16.
With this arrangement, the supplementary indicating and warning
devices 42 all turn red at point E if the aircraft fails to make the transition
from the 6 degree steep approach segment 28' to the 3 degree, shallow segment
of the approach path 28. Various arrangements may be provided for designating
changes in an approach path from a steep segment to a shallow segment and im-
mediately warning the pilot of danger by red lights turning on when a point of
~063994
danger i9 reached in the steep approach segment if he does not cau~e the air-
craft to follow the transition path to the shallow segment of the approsch path.
Vsrlation in iight units are typically lllustrated $n Pigs. 13-16
with Flg. 13 illustrating a light unit 46 having an opaque shield 48 confining
the light beam to a particular angle of observation while Fig. 14 illustrated
the same type of light unit having an opaque shield 48 and red filters oriented
as designated by numeral 50 or alternatively in an angular position as designated
by numeral 52. Fig. 15 illustrates the light unit in which the opaque shield
48 is oriented at the top of the light beam and Fig. 16 illustrates the light
unit with the opaque shield 48 at the upper end of the light beam and the red
filter 50 at the lower portion thereof with the light unit 46 in each instance
having a reflector or shield 54 associated therewith. The light 46 may be in
the form of a spotlight and the opaque shields shut out light in certain direc-
tions and the transparent red shields may convert the white light passing
through them to red light. By appropriate orientation of the shields, each
light can be made to produce a beam of white and/or red light of definite
configuration with various angles of spread and in all directions. Also, the
relative directions of the beam can be controlled. For example, the direction
or angle at which the light can first be seen can be ad~usted for each light
unit 80 that these paths can be made more or less parallel, made to diverge,
converge, and cross each other before intercepeing the path of an aircraft or
made to converge at a point of interception with the flight path. Fig. 17 illu8-
trates arrangements of this nature in which the left-hand illustration in Fig.
17 illustrates three lights oriented at points 1, 2 and 3 in which the beam~
cross and intercept the flight path 28 which is directed toward a slope indi-
cator 22 at points 1, 2 and 3 so that light number 1 will be observed by the
pilot prior to lights 2 and 3 and the lights will be observed in a sequence.
The central illustration in Fig. 17 illustrates an arrangement in which the
light beams are parallel to each other and intercept the flight path 28 in the
same orientation as they are on the ground. The right-hand illustration in
~ig. 17 illustrates the three lights which converge at a point which intercepts
the flight path 28. These arrangements can produce the effect of lightg appear-
ing in sequence in either direction or all at once even though the lights are
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on at all times but appear to be off to the pilot then appear to come on snd
can then turn red through the geometry of the ~hielding system. In effect,
the motion of the plane on or near the proper flight path or its extension
causes the off-on-change-to-red effect without employing extensive switches,
mechanical equipment or the like.
Figures 18 and 19 illustrate schematically a slope indicator and
runway together with a plurality of sequenced lights 46 which are oriented in
a manner to designate or indicate to the pilot his approach path to the end of
the runway 20. This arran8ement is especlally useful when oblique approaches
to small airports are required where obstructions exist in the straight in
normal approach. A sequenced flashing slight turn arrow 3ust before the runway
threshold would guide the pilot to the correct landing orientation while suc-
cessfully avoiding nearby obstructions with the light units 46 being either
~equenced or flashing in sequence with one of the light units at the end of
the guide arrangement being in the shape of an arrow.
These devices are for nighttime use, low visibility use, or at any
other time where either lights or a brightly painted fluorescent surface might
be used to form the desired guidance and warning for pilots. These signs or
symbols which may be in the form of arrows or pointers will indicate to the
pilot to look and fly ahead or upward from the descent path defined by a slope
indicator where such slope indicator is off the airport and used for enroute
guidance or to turn left or right as the plane nears the slope lndicator and/or
alignment indicator 80 as to aim toward the next guide unit or the airport
itself. The supplementary devices are designed to appear to the pilot at an
appropriate time, such as 3ust before he is eo negotiate a change in course,
either horizontal, vertical or combination thereof. The lights "come on" thus
attracting his attention and in some cases, they turn red as a final warning in
the event he fails to change his enroute or approach course at the proper time.
The lights may be constructed to appear to the pilot in sequence either the
farthest or the nearest light appearing first according to the situation and
the intent of the signal. The lights may be made to change red in sequence
although the most significant impact usually can be made by having all of the
lights of the device change red at the same time.
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The units may be configured as arrows, chevrons, turn arrows or
signs such as "Up" or "Turn L" or "Turn R" and the like. The lights or bars
may be supported ln any suitable manner from the ground surface or any other
suitable supporting structure and effectively provlde supplementary indicating
and warning devices to be used with the visual approach slope indicator dis-
closed in my patent No. 3,868,778.
~r
