FLIGHT SYMBOLOGY TO AID IN APPROACH AND LANDING
IN DEGRADED VISUAL ENVIRONMENTS
Margaret A. MacIsaac
Human Factors Engineer
Crew Systems Integration
Sikorsky Aircraft
Stratford, CT
mailto:mmacisaac@sikorsky.com
Lorren Stiles
Chief Pilot
Research & Development
Sikorsky Aircraft
West Palm Beach, FL
mailto:lstiles@sikorsky.com
John H. Judge
Technical Fellow, Advanced Design
Sikorsky Aircraft, Stratford CT
jjudge@sikorsky.com
This paper summarizes the results of independent research and development addressing
deficiencies in current flight symbology presentations, which contribute to landing incidents in degraded
visual environments. Of particular emphasis was the symbology to aid a pilot in establishing a
stabilized approach to touchdown where the visual environment degrades suddenly due to rotor
downwash surface effects such as dust, sand, and snow.
The program investigated the current display formats and information content, as well as
historical data on “brownout” landing incidents, to determine where deficiencies lie. It was clear that
improvements in the method to cue the pilot to the aircraft state, as well as directing the pilot to develop
and maintain a stabilized approach profile were needed. Specific solutions for each deficiency, such as
lack of resolution in display of lateral groundspeed, were developed. Each solution was evaluated to
determine if it resolved the targeted shortcoming. The solutions were then combined into an integrated
display format. Sensitivities to changes in wind direction, gusts, etc were also investigated.
A variety of display palettes were considered: from basic primary flight/hover display (PFD) to
advance head up, head tracked, helmet mounted (contact analog) technologies, the intent being to enable
implementation of improved information displays into a wide range of aircraft cockpits, from off the
shelf to next generation.
Fixed based simulation evaluations, with realistic brownout environmental simulations, were
used to evaluate the design approaches. Data were collected to document performance improvements.
Technical studies were conducted to evaluate the feasibility of adding visionics to the flight
symbology displays. This included both the need and requirement for stabilizing the sensors, means to
incorporate the imagery as underlays to existing display formats, as well as the feasibility of fusing
differing sensor frequencies to develop a multi-spectral visual-like image capability of operating in the
demanding “brownout” environment.
Integration of advanced control laws, that will become available as fly by wire technology
matures, were also investigated. Integration of flight symbology cueing to command steering for
stabilizing the final stages of the approach were investigated.
Specific solutions to the “brownout landing” problem will be presented. Suggested
modifications to flight symbology on typical primary flight displays (PFD) will be presented. Results of
simulation trials will be presented. Finally, potential future improvements will be provided.
Presented at the American Helicopter Society 61st
Annual Forum, Grapevine, TX, June 1-3, 2005.
Copyright 2005 by the American Helicopter Society
International, Inc. All rights reserved.
pilot. Thus, the brownout condition makes it
difficult if not impossible to detect drift. As
a result, the military has been seeking
solutions in and out of the cockpit including
the utilization of chemical mats, new tactics
that include coordination among crew chiefs
and pilots to “outrun” the brownout cloud,
and potentially fielding a new display-sensor
suite2. The focus of this paper is on flight
symbology to aid pilots in landing during a
brownout condition.
Introduction
Helicopters are routinely required to
land at remote sites without the aid of
navigation guidance, as reported in Iraq and
Afghanistan. Pilots returning from the field
report that the desert environment consists of
such fine dust that it is almost impossible to
counteract. As stated in an earlier paper1, “the
fineness of the soil and sand has redefined the
meaning of brownouts (“dust outs”) – the dust is
so fine that the difficulties begin earlier in the
approach than normally experienced and dust
clouds persist for long periods of time.”
Problem Analysis
It is interesting to note that the problem
for the helicopter differs greatly from the
fixed wing airplane. The airplane designs
have typically targeted the transition from
instrument meterological conditions (IMC)
to visual conditions (VMC) at lower
altitudes, thus improving the probability of
completing a specified approach procedure
to a prepared airfield. The airplane
maintains a stabilized approach profile,
including a fixed speed, until in visual
conditions, where the flare to touchdown
results in landing in a stabilized flight
condition on a prepared surface. If visual
conditions are not achieved, the landing
must be aborted.
The tactical helicopter encounters
exactly the opposite situation. The
approach commences with visual references
to an unprepared landing point. The
approach procedure requires the pilot to
determine the proper approach path,
deceleration rate, and rate of descent to
successfully arrive at the landing point at
zero (or low) forward velocity. At some
point during the approach procedure, the
Figure 1.
Brownout landing in Iraq 53E
The dust and sand is kicked up by the
rotor downwash resulting in a “brownout”
which means all visual cueing is lost while
very low to the ground. The human eye is
dependant upon outside visual cues that
provide optical flow or movement and
thereby convey a sense of motion to the
1
“Lessons Learned From Operation Enduring Freedom:
Implications for CV-22”. American Helicopter Society.
Phoenix, AZ. 2003.
Presented at the American Helicopter Society 61st
Annual Forum, Grapevine, TX, June 1-3, 2005.
Copyright 2005 by the American Helicopter Society
International, Inc. All rights reserved.
“US Army to field interim solution to resolve helicopter
brown-outs”.Flight International. April 2004.
2
pilot transitions to IMC conditions and must
complete the landing without the benefit of
visual references. This approach is depicted
in Figure 2.
Figure 2.
Elements of Brownout Approach
Much of the technology investigations
have focused on providing the pilot with visual
references when in the IMC portion of the
profile. Sensors that can “see through” the
obscurants of the brownout (synthetic and
enhanced vision) have been mainly developed in
the fixed-wing commercial domain. Relatively
speaking, the challenges facing the fixed wing
environment are simple and straightforward.
The fixed wing world needs a sensor that can
see through fog, the primary limiting condition
to successful landings. The helicopter operator
requires to see not only through fog, but many
other types of obscurants, from blowing snow,
to dust and sand, and smoke. Thus far, no one
single sensor technology is able to meet these
needs.
Through previous research3 we
understand that the solution to a helicopter
3
Solutions that Permit Safer Flight in Degraded Visual
Environments, J. Judge, K. Bredenbeck, V. Sahasrabudhe,
Sikorsky Aircraft, 2004.
Presented at the American Helicopter Society 61st
Annual Forum, Grapevine, TX, June 1-3, 2005.
Copyright 2005 by the American Helicopter Society
International, Inc. All rights reserved.
successfully landing in a brownout environment
is a multi-faceted one. As stated by J. Judge,
“the ultimate solution to brownout and obstacle
avoidance includes the integration of new and
existing sensor technologies, the deployment of
intuitive cockpit displays and the application of
advanced flight controls that improve handling
qualities”. We have identified these three areas
of technology as key components integral to the
brownout solution, that is, flight controls (fly by
wire), advanced sensor(s) and information
content or flight symbology. Because helicopter
crews need a low-cost, rapidly deployable,
fieldable solution today, we have focused on
optimizing flight symbology for a brownout
approach.
The focus of this paper, then, deals with
analyzing existing helicopter crew approaches
to dealing with brownout, with the prime focus
on how existing flight symbology aids the
operator in that task. As a result of this analysis
the “hover display” became the prime focus.
Understanding how the pilot(s) uses the
components of the hover display for cueing as to
control inputs needed was the basis for
developing improved symbology.
Brownout Approach
As discussed in the Problem Analysis
section, the “brownout” approach does not
differ from the normal approach to a remote
landing site, except that sometime during the
profile the pilot will lose visual references. The
approach procedure requires the helicopter pilot
control the flight path of the aircraft while
making the transition from cruise flight to zero
velocity at a specific touchdown point. Simply
stated, the pilot must establish an approach path,
using an angle which is clear of obstacles, and
decelerate and descend at a controlled rate
which results in arrival at the desired point.
Some aircraft are required to follow a specific
profile (decelerate and descent rate) to maintain
performance margins.
Information Requirements
Several elements of information are
necessary while making the approach (all are
acquired primarily through visual references):
1. Rate of horizontal closure to the landing
point
2. Lateral drift
3. Steady heading (no aircraft rotation at
touchdown)
4. Rate of vertical closure to the ground
5. Obstacle-clear flight path to the landing
point
6. Surface analysis
a. free of obstacles
b. suitable for gear touchdown (no
holes, bumps, etc)
c. slope
An absence of information on any one of the
elements above can result in a brownout
incident or accident. Specifically, the causes of
aircraft damage in a brownout are historically:
 Lateral drift, excessive forward speed at
touchdown
 High rate of descent at touchdown
 Touchdown with one or more landing
gear on an obstacle or slope.
During our analysis, it became clear that
much of the information being acquired visually
could be presented via symbology – as long as
the symbology was easy to use as an
augmentation to visual cues, or the transition to
the symbology presentation at the point of IMC
transition was easy and smooth. CV-22
engineers from Bell have stated that “The
unpredictable nature of this transition (VMC to
IMC rather than pure IMC flight), the
determination of when the transition should
Presented at the American Helicopter Society 61st
Annual Forum, Grapevine, TX, June 1-3, 2005.
Copyright 2005 by the American Helicopter Society
International, Inc. All rights reserved.
occur, and the resulting scan pattern and control
strategy shift can be unsettling, making it
difficult for crews to perform consistently. This
transition can occur in the last 30-60 seconds of
the flight. As a consequence, there is practically
no time for the flying pilot to adjust or adapt to
the new flight conditions”. The major challenge
was to develop a symbol set that met these
criteria.
Ideally the symbology must also aid the pilot
in determining control strategy for the
successful approach. Analysis of recent
developments in symbology reveal an emphasis
on trend indications. This element of
information is quite useful to the pilot as it
provides an early indication that control
strategies will have the desired effect on flight
path. The authors attempted to incorporate
trend indicators on the same display surface as
the primary indication as a means to allow the
pilot to make the most of the trend cue.
A task based analysis of the approach
profile was undertaken to gain insight into the
operators’ tasks. Once the tasks were broken
down and understood, the authors could then
have a baseline with which to improve the flight
symbology. The specific tasks undertaken by
the operator during the brownout approach are:
1. Stabilize the approach before
entering cloud
2. Eliminate lateral drift prior to
touchdown.
3. Maintain heading stability during the
final phase of the approach.
Existing Symbol Sets
As part of this research, an analysis of
existing information display sets (symbology)
was undertaken (i.e. 60M Figure 3 below). Most
fielded helicopters lack the display media to
provide symbology presentations practical.
There is evidence that the US Military is
recognizing the need and value of “glass”
displays in recent aircraft acquisitions such as
the AH-64D, OH-58D, HH-60L, MH-60S
which incorporate multifunction display
capability. In addition, retrofit programs are
under discussion. Perhaps it is incumbent upon
industry to show the value of these displays
before expecting the military customer to make
such an investment.
Figure 3.
UH-60M Hover Display
Without the augmented information provided by
multifunction displays, the successful brownout
is accomplished mainly by crew training.
Techniques vary by aircraft type and service,
but usually include standardized procedures to
be invoked when the “brownout” situation is
encountered. For example, the CH-53E crew
(USMC) posts an observer on the ramp which
can call out to the cockpit when the dust cloud is
beginning to form. The pilot then stabilizes
aircraft parameters, such as pitch/roll attitude
and power, so the aircraft lands under control.
The UH-60L crew will use information from
observers posted on the sides of the aircraft,
who look out the cabin directly at the
Presented at the American Helicopter Society 61st
Annual Forum, Grapevine, TX, June 1-3, 2005.
Copyright 2005 by the American Helicopter Society
International, Inc. All rights reserved.
ground, to determine lateral drift. The authors
concluded that pilots would be better served
with information provided directly into the
cockpit, in the form of symbology.
As mentioned earlier, much effort has
been placed on development of sensors that can
provide an image in the presence of obscurants
which create the “brownout” effect during
landing. Our analysis indicated that, even if the
ideal imaging sensor were available, there was
considerable questions on how to display the
image. The means to stabilize the sensor and
method for displaying the image in a cockpit
without a helmet display capability was unclear,
for example. At slow speeds, the flight path of
the helicopter changes rapidly so simple flight
path stabilization is impractical. A means to
filter the commanded line of sight of the sensor
needs to be developed. The limited field of
view of a practical sensor would not provide
enough information to replace the pilot’s visual
cues. Even providing a clear reference to the
airframe was challenging.
Thus, the focus on symbology became the most
apparent, practical near term development
solution.
METHOD
Throughout this research we sought to
improved existing symbology deficiencies and
optimize the hover display symbology for the
brownout approach. Out method also consisted
of limiting changes to software only.
Address information deficiencies:
Shortcomings of existing hover display
symbology sets were analyzed and addressed.
While the original hover display was originally
driven by the need for hover cues, it was
discovered through this analysis that the hover
display symbology lacks cueing to address
information requirements in a brownout
approach. That is:
1. Lateral drift cueing is insufficient.
2. There is no specific heading
reference cue, except for the pilot’s
memorization of the compass
reading
3. There is no indication of rate of
closure to the ground (only airmass
climb/descent rate)
New symbology
The deficiency in the indication of
lateral drift is due to the method for presenting
Presented at the American Helicopter Society 61st
Annual Forum, Grapevine, TX, June 1-3, 2005.
Copyright 2005 by the American Helicopter Society
International, Inc. All rights reserved.
velocity through the “vector” format. While the
velocity vector is intuitive to read because it
represents the aircraft state in a literal horizontal
format, it does not provide off axis precision.
That is, when the objective is to conduct an
approach, the axis of interest is along the
longitudinal path of the aircraft. Thus, the
velocity vector is oriented primarily up and
down. Any indication of lateral velocity is
provided by the angle the vector is presented off
axis, which for small values is difficult to
perceive. Very small lateral velocities can be
tolerated, however, which implies very small off
axis angles – thus the problem with the vector
presentation.
A lateral velocity error bar was designed
and added to the baseline hover display. This
error bar consisted of a colored line that
extended from either side of the ownship
symbol in the center of the hover display. This
bar increased in proportion to ground speed to
indicate to the pilot that lateral velocity is in
“error”, or greater than zero. Thus, the error bar
acts as a symbolic representation of left or right
lateral drift. For example, if the aircraft drifts
right, the error bar will “grow” from the right
side of the aircraft symbol. Should the aircraft
zero its lateral drift, the error bar retracts and
disappears from the display. The bar is green
when lateral drift is between 0-2 knots and
yellow when greater than 2 knots (almost 4 feet
per second) lateral deviation/drift. The length of
the lateral error bar is determined by calculating
the lateral component of the aircraft ground
velocity and multiplying by a scale factor which
is dependent on the display capability (in this
case, the scale factor is “3”). By up scaling the
indication, the pilot is provided with more off
axis precision, and since the objective is to
make drive lateral velocity to zero, the error bar
approach is quite effective. Figure 4 depicts the
relationship between the velocity vector and the
lateral velocity error bar. Figure 5 presents the
integration of the lateral velocity error bar with
the velocity vector on the hover display.
presentation was quite effective. Figure 6
depicts the display method for the heading error
bar. To se the desired heading, the pilot
depressed a button on the collective control grip.
This initiated the approach mode, which
included setting the heading reference, along
with other functions to be discussed later.
Longitudinal component
Velocity vector
Origin
355 36
33
Lateral velocity error bar = 3 x Lateral component
Figure 4.
Lateral velocity error bar
calculation
Velocity
vector
Error bar
Figure 5.
Integration of lateral velocity error bar
To address the lack of a heading
reference, another error bar approach was taken.
In this case, the error bar indicates the
difference between the desired approach
heading and the current heading. Once again,
since the objective is to make this difference
equal to zero, the error bar method of
Presented at the American Helicopter Society 61st
Annual Forum, Grapevine, TX, June 1-3, 2005.
Copyright 2005 by the American Helicopter Society
International, Inc. All rights reserved.
Figure 6
Heading error bar
An improvement was made to the radar
altimeter display to provide a rate or trend
indication. The radar altitude trend was
calculated by computing the rate of change of
radar altitude and multiplying the result by a
time constant. This resulted in a trend by
depicting a predicted value for the radar altitude
at a time in the future determined by the value
of the time constant. In our experiment, we
used a time constant of 6 seconds. This allowed
the pilot to use the ten-foot increment already
resident on the display to gauge a 100 fpm rate
of descent (ten foot change in 6 second is equal
to 100 fpm). Figure 7 presents the method for
displaying height above ground trend
information.
Radar altitude trend – predicted
value 6 sec in future
50
pitch and roll attitude needed to acquire the
desired aircraft velocity states. Figure 8. shows
the presentation method. Time ran out before
the algorithms could be fully developed for this
command steering approach, but it was decided
to present a simplified version to the pilots
during the study to garner qualitative comments.
A more complete investigation of this approach
will be conducted at a later date.
355 36
33
89
3
2
1
0
Figure 7.
Radar altitude trend indication
Finally, an attempt was made to develop
a method for presenting command steering
information to the pilot to assist in determining
correct control inputs to maintain a stabilized
approach. The goal was to provide symbology
integrated with the hover display which
represented flight director-style commands to
maintain a stabilized deceleration rate with pitch
inputs, and zero lateral velocity with roll inputs.
Based on USAF research, a modified version of
the “non directional flight reference (NDFR)”
symbology was used4. The NDFR provided an
indication of current pitch and roll attitude, upon
which were overlaid command cues for the
“Development of a Non - Distributed Flight Reference
for Helmet-Mounted Display Use During Off-Boresight
Viewing”. Air Force Research Laboratory. Geiselman,
Eric. 2002
4
Presented at the American Helicopter Society 61st
Annual Forum, Grapevine, TX, June 1-3, 2005.
Copyright 2005 by the American Helicopter Society
International, Inc. All rights reserved.
NDFR with command cues
Figure 8.
NDFR command cue presentation
Evaluation Facility
The facility used for this evaluation was
the Sikorsky fixed base simulator. The device
consists of a UH-60 cockpit, including the
mechanical control system and instrument
panel. During baseline trials, the primary flight
display (PFD) with hover mode symbology,
presented on a 6x8 inch multifunction display,
was utilized. During trials of the experimental
DVE symbology, an 11x14 flat panel display
was utilized, and a PFD which incorporated the
modifications associated with the experimental
symbology was utilized. Conventional UH-60
mechanical controls with the basic stability
augmentation mode (SAS/FPS, which provide
rate damping and attitude/heading hold) was
utilized, with no advanced control laws, as this
was the level of augmentation likely to be
encountered in a fielded aircraft that might
receive the modified symbology.
The simulation incorporated a
“brownout” special visual effect model, which
caused the out-the-window scene to degrade as
if the aircraft encountered dust obscurants.
Depending on forward speed and altitude, the
brownout effect resulted in a completely IMC
condition. As the aircraft altitude and speed
was reduced during the approach, the dust
“cloud” appeared. A combination of
approximately 20 ft and 7 knots speed resulted
in a complete loss of visual references. Two of
the subject pilots had just returned from active
duty tours in the mid-east, and reported the
special effect to be quite realistic.
Experimental Setup
Subjects flew 3 approaches in each
mode. The modes were:
 Baseline UH-60M standard PFD/hover
display).
 Experimental symbology incorporating
lateral velocity error bar, heading error
bar, and rescaled radar altimeter with
“predictor” cue to indicate rate of
closure
 Experimental symbology incorporating
all of the above modifications, as well as
a Non-directional flight reference
(NDFR).
Presented at the American Helicopter Society 61st
Annual Forum, Grapevine, TX, June 1-3, 2005.
Copyright 2005 by the American Helicopter Society
International, Inc. All rights reserved.
The runs were initialized in stabilized
level flight at 80 knots and 300 ft. A landing
zone (LZ) was visually identifiable and subjects
were asked to land in the center at less than 5
knots, less than 1.5 knots lateral velocity, and
less than 125 fpm rate of descent. Limited
training time was available, so subjects were
allowed to land outside the LZ if necessary.
Subjects were told to focus on stabilizing the
aircraft state within desired parameters at
touchdown. No handling qualities ratings were
elicited, as performance was the primary focus
of the experiment.
Data were collected on flight state
during the approach and at touchdown. The
following figures summarize the most critical
parameters: longitudinal speed (Vx) at
touchdown, lateral speed (Vy) at touchdown,
and vertical speed (Vz) at touchdown.
Results
Comments from participating pilots were
elicited at the end of each approach task. In all
cases, pilots noted improved information
transfer with regards to critical parameters.
Lateral velocity and rate of descent cues
overlaid on the radar altitude display were cited
as the most beneficial improvements. Pilots
stated these indicators helped achieve
acceptable performance, particularly at the end
of the task. Color coding of these parameters
was cited as extremely beneficial because it
eliminated the need to spend much of the scan
time on the parameter, allowing more time to
cross check other parameters in the display.
Some pilot commented the display created
“information overload” because so much detail
was provided in the symbology. While
acknowledging the information was required to
successfully terminate an approach once the
brownout conditions were encountered,
4
3
DVE mode
2
Baseline mode
1
13
11
9
7
5
3
0
1
Lateral Velocity (knots)
Lateral Velocity at Touchdown comparison
Run #
Table 1
Table 2 compares longitudinal velocity
comparison at touchdown. Pilots using the
DVE symbology consistently performed to
slower touchdown speeds. Feedback indicated
that the longitudinal velocity was considered by
many pilots as the most important parameter,
and the DVE lateral velocity error symbology
provided the time to cross check parameter
while maintaining the other parameters within
constraints.
Longitudinal Velocity at Touchdown
comparison
10
8
6
4
2
0
DVE mode
13
11
9
7
5
3
Baseline mode
1
Longitudinal
velocity (knots)
compiling all the information in a compressed
time period – as is experienced during the final
phase of the approach – was challenging. These
comments were most common when the NDFR
symbol was introduced into the display. This
resulted in several levels of information being
presented in one area: “raw data” indications of
aircraft state, “trend data” indications of future
aircraft state, and finally the NDFR which
provided guidance to achieve the desired aircraft
state.
The NDFR algorithm was a simplistic
linear deceleration command, and used roll
attitude to control lateral velocity. It was clear
that a non-linear approach was needed, and that
lateral velocity and yaw control needed to be
coordinated to control lateral velocity. Because
of this, the NDFR symbol was more distracting
than beneficial.
Data indicate little quantitative difference
in the critical parameters. Comparisons are
made between the performance of pilots using
DVE and non-DVE symbology (referred to in
the data as “Baseline” mode). The following
tables summarize the results. The runs in tables
2, 3, 4 compare the best and worst runs without
regard to pilot.
Table 1 compares lateral velocity at
touchdown and shows a slight improvement for
the DVE symbology when the touchdown speed
is very slow. This may indicate improved
information transfer for the pilot once a training
threshold has been met. It also indicates a
“worst case” performance which still meets the
criteria for successful landing, whereas nonDVE symbology does not.
Run #
Table 2
An interesting observation was made when
further analyzing the touchdown speeds in DVE
and Non-DVE modes. When comparing the
longitudinal touchdown speed to the lateral
Presented at the American Helicopter Society 61st
Annual Forum, Grapevine, TX, June 1-3, 2005.
Copyright 2005 by the American Helicopter Society
International, Inc. All rights reserved.
touchdown speed, one can conclude the DVE
mode results in better overall performance
because we see lower longitudinal touchdown
speeds when lateral velocity is low. In the nonDVE mode, when lateral touchdown speeds are
very low, longitudinal speed tends to be much
higher, indicating the pilot’s inability to monitor
one parameter while optimizing the other. This
was consistent with pilot comments as well.
Tables 3 and 4 present these data.
completely flat terrain with very few obstacles.
Thus, the vertical speed indication provided by
the air data system was of as much value as that
provided via the radar altimeter filtered data.
Vertical speed was also a very familiar
parameter for the evaluations pilots who were
familiar with the baseline symbol set being
used. The data contradict the universal
comment by the pilots who observed the
rate/trend data being overlaid on the radar
altimeter as being very beneficial and intuitive.
DVE mode - touchdown speed
Vertical speed at touchdow n com parison
10
25
22
19
16
13
10
7
4
1
0
Baseline mode
1
Run #
DVE mode
13
Vy
2
10
4
500
400
300
200
100
0
7
Vx
4
6
Vertical speed
(ft/min)
Knots
8
Run #
Table 3
Table 5
Baseline m ode - touchdow n speed
10
Knots
8
6
Vx
4
V
Vy
The heading error bar was counterintuitive and, as a result provided little
conclusive results. Instead of presenting the
origin of the arcuate indicator as the desired
heading, with the error bar indicating error from
desired, we
2
Conclusion.
13
11
9
7
5
3
1
0
Run #
Table 4
Table 5 presents the vertical velocity at
touchdown. Little difference is seen between
performance using the non-DVE and DVE
symbology. This may be a fall out of the
simulation task which was flown over
Presented at the American Helicopter Society 61st
Annual Forum, Grapevine, TX, June 1-3, 2005.
Copyright 2005 by the American Helicopter Society
International, Inc. All rights reserved.
The methodology employed was
successful in determining the problems that lead
to brownout accidents; we are confident we
have targeted the correct requirements. We have
also concluded that existing hover display
symbology was designed for aid in the hovering
task, not brownout approaches and/or landings.
Continued research is needed to re-run the
simulator study with more subjects and
symbology algorithm adjustments.
The “all capable” ideal sensor or fused
sensors may not be the solution in and of itself.
Investigation is needed on how crews could
utilize such information for low-level pilotage
and landing. These issues extend beyond the see
through capability of sensors to numerous
human factors issues such as field of view, head
up/head down display capabilities, compression
References:
Department of Defense, MIL-STD-1787C
Interface Standard for Aircraft Display
Symbology February 2000
Department of Defense, MIL-STD-1295A
Human Factors Engineering Design Criteria for
Helicopter Cockpit Electro-Optical Display
Symbology. 1984.
Geiselman, Eric E. “Development of a NonDistributed Flight Reference for HelmetMounted Display Use During Off-Boresight
Viewing”. Air Force Research Laboratory. 2002
Flight International. April 6, 2004. “U.S. Army
to field interim solution to resolve helicopter
brown-outs”.
Presented at the American Helicopter Society 61st
Annual Forum, Grapevine, TX, June 1-3, 2005.
Copyright 2005 by the American Helicopter Society
International, Inc. All rights reserved.
rates, and symbology, to name a few. With
continued research and dedication to this issue
we are confident that we continue to make
headway into this complex problem facing our
helicopter crews.
Tatro, Jon S., Hargis, Michael, and Magness,
Matt. “Lessons Learned From Operation
Enduring Freedom: Implications for CV-22”.
American Helicopter Society. Phoenix, AZ.
2003.
Judge, J., Bredenbeck, K., and Sahasrabudhe V.,
Sikorsky Aircraft. “Solutions that Permit Safer
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