AAWSAP DIRD Cockpits in the Era of Breakthrough Flight November 1 2010
⚠ Texto extraído por OCR de la fuente oficial — puede contener errores de reconocimiento. El documento original es la autoridad.
UNCLASSIFIED/ /FOR OFFl@lslll:. WOE OF.I:¥
Defense
Intelligence
Reference
Document
Defense Futures
01 November 2010
ICOD : 8 Ju ly 2010
DI A-08- 1011 - 002
Cockpits in the Era of
Breakthrough Flight
UNCLASSIFIED//FOR 8FFl@IAI:. WOE 0 .. 1:.lf
UNCLASSIFIED//F8R 8FFIOIAL YSE BHLY
Cockpits in the Era of Breakthrough Flight
The Defense Intelligence Reference Document provides non-substantive but
authoritative reference information related to intelli ence to ics or methodolo ies.
Prepared by:
Technology Warning Division (DW0-4)
Defense Warning Office
Directorate for Analysis
Defense Intelligence Agency
Author:
AAP Person 82
Administrative Notes:
(U) COPYRIGHT WARNING: Further dissemination of the photographs in this publication is
not authorized .
This product is one in a series of advanced technology reports produced in FY 2009 under the Defense
Intelligence Agency, Defense Warning Office's Advanced Aerospace Weapon System Applications
AAWSA Pro ram. Comments or questions pertaining to this document should be addressed to ,....- ...-___-..
_,M_E,__Person
AAP Person 1 AWSA Program Manager, Defense Intelligence Agency, ATTN: JUIAF - DI/DWO-3,1 ••
g , as mg on, DC 20340-5100.
UNCLASSIFIEDf,/liOA OliliiliCiliOL Plltli Otill¥
UNCLASSIFIED/ ,'FOR OFFI@IAL WSE ONLY
Contents
Introduction .. .........................................................................................................iv
Chapter 1: Predicting Implications of Propulsion Breakthroughs ........................... 1
MARCH OF PROGRESS: REVOLUTIONARY PROPULSION PHYSICS ....................... 1
VEHICLE and COCKPIT IMPLICATIONS ............................................................... 2
Chapter 2: Human-Machine Interface Lessons ..................................................... 18
HUMAN PERCEPTION NORMS ........................................................................... 18
DESIGN FOR STRESS ........... ....... ........... ......... ...... . ........ .... .......... ........ .... ....... ..... . 21
DEVICES TO CONVEY INFORMATION ................................................................ 23
DEVICES FOR RECEIVING PILOT COMMANDS ................................................... 27
CONTEMPORARY AIRCRAFT COCKPITS ............................................................. 28
Chapter 3: Provisional Cockpit for Breakthrough Flight.................... .................... 32
FLIGHT MODES ................................................................................................. 32
PHYSICAL DISPLAVS .................................................................... ... ............... .. 34
VIRTUAL SURROUND DISPLAY ......................................................................... 40
CO NTROLS ........................................................................................................ 41
Chapter 4: Future Work ........................................................................................ 43
MULTIPLE FLIGHT REGI ME GUIDANCE CONVENTIO NS ..................................... 43
VECTOR MOTION DISPLAY ............................................................................... 43
VECTOR MOTION CONTROL .............................................................................. 43
OPTIMUM MIX OF CONTROL METHODS ............................................................. 44
Appendix A: Annotated Bibliography ......... .. ......................................................... 45
Appendix B: Endnotes .......................................................................................... SO
Figures
Figure 1. Six Independent Degrees of Freedom ...................................................... 3
Figure 2. Comparing Conventions of Aircraft Motion .............................................. 5
ii
UNCLASSIFIED/ fFOA. OFFICIO Is. flili Ol'lls.¥
UNCLASSIFIED/ ,'FOR OFFI@IAI:: ~SE OPtl::Y
Figure 3. Necessary Distinction Between External & Internal Force Environments. 6
Figure 4. Warp Drive ...............................................................................................8
Figure 5. Hypothetical Gravitational Bias Drive .......................................................9
Figure 6. Inertial Frame Bias Drive and Vehicle Zones ..........................................10
Figure 7. Typical Science Fiction Orientations .......................................................12
Figure 8. Cosmic Microwaves as Universal Motion Reference Frame ..................... 15
Figure 9. Human Fields of View .............................................................................20
Fig ure 10. Flight Deck of Contemporary Aircraft ...................................................29
Figure 11. Contemporary Primary Flight Display ............. ......................................30
Figure 12. Space Cockpit Visions Ci rca 1959 ....... .... ...... .. ................................... ... 31
Figure 13. Provisional Breakthrough- Era Cockpit ..................................................33
Figure 14. Functional Designation of Physical Cockpit Panels......... ....... .... ..... ....... 34
Tables
Table 1: Comparing Reaction Time to Distance Traversed at Various Speeds .. ... .. 13
iii
UNCLASSIFIED/fFOA. OFFICIO ls. Plili ONls.¥
UNCLASSIFIED/ ,'FOR OFFI@IAL WSE ONLY
Cockpits in the Era of Breakthrough Flight
Introduction
Responding to the request to explore forefront science relevant to future cockpits for
any form of aerospace craft and/or deep-space craft that is propelled by any
unspecified advanced or breakthrough propulsion physics, th is report offers a
provisional cockpit design that employs the following:
• Predictions of propulsion physics breakthroughs.
• Lessons of human-machine interface.
• Emerging technology for displays and controls.
This study discusses the implications of breakthrough propulsion, includ ing the mastery
over gravitational and inertial forces and the prospect for faster-than-light spaceflight.
The main reference used to predict these possibilities is the book Frontiers of Propulsion
Science [Millis & Davis, 2009]. Although the breakthroughs discussed in this book are
not imminent, enough progress has been made to allow for thoughtful speculation
about their characteristics and possible implementations.
How these advances may affect future cockpits is described, and this is the central
message of this study. The most significant differences from legacy cockpits are
identified and then used to set the baseline design requirements.
Additionally, substantial lessons about human-machi ne interfaces are reviewed and
applied to this notional cockpit. Most of this progress relies on better accommodating
the norms and limitations of human perception-lessons that do not change even when
vehicle characteristics change.
Recent advancements in the use of hand gestures for commands are also included, as
well as advancements in brain-machine interfaces. In this conceptual study of far-future
possibilities, these technologies are assumed to have reached fu ll maturity, with one
exception: in order to focus this study on future cockpits, the options for brain implants
and for transhumanism-where humans are reengineered to adapt to new
requirements-are not considered.
Next-step investigations are suggested to refine the ideas presented herein. A caveat
is that advances in cockpits for breakthrough flight might be further advanced by taking
advantage of the gaming industry techniques or through science fiction speculation.
Note: All projections in this report are based on public domain informati on.
iv
UNCLASSIFIED/fFOA. OFFICIO ls. Plili ONls.¥
UNCLASSIFIED/ ,'FOR OFFI@IAL WSE QptLY
Chapter 1: Predicting Implications of Propulsion
Breakthroughs
MARCH OF PROGRESS: REVOLUTIONARY PROPULSION PHYSICS
Breakthroughs in propulsion physics (such as the control over gravitational or inertia l
forces, propellant-less space drives, and even faster-than-light travel) are not
imm inent; however, enough progress has been made to allow for thoughtful
speculation about their nature and implications. As a preview, the implications to
cockpit design include added degrees of motion, combination of operational regimes
(near ground, orbit, and beyond), greater range of speed (from zero-speed hover to
beyond light speed), and loss of familiar motion cues (pilot's inertia and visual cues)
resulting from the separation of external and internal environments.
The primary reference used to predict these possibilities is the book Frontiers of
Propulsion Science [Millis & Davis, 2009], 1 particu larly chapters 3, 4, and 15. This book
may be the first-ever scholarly compilation of science pertaining to breakthrough
flight-methods sufficiently advanced to enable human voyages to other star systems.
The book examines a wide range of works, offering introductory explanations and
comparisons between approaches and identifying high -priority unknowns needing
deeper study. References to specific ideas and issues cite that book and other orig inal
works.
Setting Ideal Performance as Design Target
This report focuses on the most sign ificant likely differences between contemporary
cockpits and cockpits in the era of breakthrough flight. Possibilities that imply the most
demanding changes are considered first, and explanations of the correlations between
the propulsion characteristics and resulting cockpit features are provided . Looking to
the far future, this study evaluates the impact of having achieved the following
breakthrough advancements:
• Control over gravitational and inertial forces:
- The craft is propelled by int eract ing with t he properties of the space-t ime and/ or
inertial frames su rround ing the craft- and can accelerate at g levels beyond
human endura nce .
- The environment inside a craft can be sustained anywhere between 0 g and 1 g
(m inimum range) without regard for either the motion of the craft or its outside
gravitational environment.
• Faster-than -light (FTL) speeds are possible by hav ing mastered control over t hose
aspects of nature that impose the light-speed limit. However, due to reasonable
re lativistic projections of the energy required for propulsion coupled with the limits
of the human lifespan, it is reasonable to expect that travels will be limited to within
our galaxy. For the sake of bracketing the scope of coverage, this study assumes
that practical star flight will be limited to a 100-light-year radius around our Sun.
Even with this constraint, thousands of star systems are within that range.
1
UNCLASSIFIED/fFOA: OFFICIO la Plili Oralla¥
UNCLASSIFIED/ ,'FOR OFFI@IAI:: WSE ONl::Y
• The energy supply for these features resides on the vehicle and is cons idered to
have a dynamic interplay with the motion of the vehicle . The energy can be
transferred to and from the environment surrounding the craft as a consequence of
the propulsive maneuvers.
Sanity Check on Predictions
Objectively, the propulsion physics pred ictions offered in this report should be
interpreted as informed conjectures or, at best, well-reasoned speculations. Absent of
verified theories and engineering implementations, it is premature to consider this first
study as the last word on this topic. Further progress will likely reduce the span of
options and provide greater insight into implementation details.
It must also be stressed that these interpretive predictions and cockpit implications are
solely generated by the author and, thus, have not yet been published or debated with
other scientists and engineers. Therefore, the reader should consider these predictions
to be an initial step into the process.
VEHICLE AND COCKPIT IMPLICATIONS
~deally, it is desirable to have a vehicle that can move in any direction, at any speed, in
both air and space, without limitations. These features imply the need to have
technological mastery over the forces of gravity and inertia and mastery over those
aspects of nature that impose the light-speed limit. Based on projections of the
underlying physics, such abilities would have secondary characteristics that affect how
such motions are monitored and controlled.
Degrees of Freedom
Unlike an aircraft, whose motion consists basically of deviations from constant forward
motion, or a helicopter, whose motion is dominated by t he dynamics of its main rotors,
a breakthrough propulsion vehicle would allow the full six degrees of freedom, including
the ability to remain fixed relative to a desired reference. For example, if we start with
the situation of a vehicle hovering over the ground, the breakthrough vehicle should be
able to change its orientation (yaw, pitch, or ro ll) without affecting its altitude or lateral
position. Similarly, it should be able move up/down or laterally without the need to
induce pitch or roll maneuvers (Figure 1).
Such novel motion leads to two major differences from legacy cockpits:
• Independent control inputs are needed for the full six degrees of freedom (yaw,
pitch, and roll; and laterally, x [fore-aft], y [ left-rig ht], and z [up-dow n]).
• New display methods are required to convey position, orientation, and motion for all
those degrees of freedom.
The control methods need not copy legacy methods from airplanes or helicopters
methods that are based on the mechanisms of their origin (Figure 2). Instead, future
cockpit designs are now free to use control methods tailored to the natural
action/reaction of pilots, whi le t he vehicle's interfaces perform the function of
converting pilot inputs to drive the veh icle's motion. Whether such a system consists of
2
UNCLASSIFIED/fFOA. OFFICIO ls. Plili ONls.¥
UNCLASSIFIED/ ,'FOR OFFI@IAL WSE QptLY
a single joystick with six degrees of freedom, some sort of gesture-based system, or
one that has those degrees of freedom dispersed across multiple pilot inputs (e.g ., head
motion, legs and feet, and arms and hands) remains open for future study. As a
provisional baseline, th is report chooses the option of having a pair of six-degree-of
freedom joysticks, one for both the left and right hands and located at the edge of the
cockpit chair's arm rests.
Th ree equally avalla ble recti linear axes of motion Three equally available rotational axes of motion
Figure 1, Six Independent Degrees of Freedom. [Graphic : A. Szames] Note : the vehicle shown is strictly
hypothetical and is a combination of three 1960s science fiction vehicles: Seaview submarine, Galileo shuttle, and
Amtronic car.
Simi lar to requiring new control methods, new display methods are also required to
convey more information than in legacy cockpits. In addition to the complete six
degrees of freedom, these motions will take place near the Earth's surface, in orbit, and
in deep space. A key difference spanning those regimes is the traditional role played by
a gravitational field as a reference for orientation and motion. Since a gravitational
reference will not always be present, and yet is extremely important when it is present,
the new display system must accommodate all regimes in a way that feels natural to
the pilots. These particular challenges are addressed in the section on Mixed
Operational Regimes.
Separation of Internal and External Environments
Probably the most significant and perplexing difference for breakthrough-era cockpits is
that the sensations of motion inside the vehicle will not necessarily match the motion of
the vehicle itself. This is both a consequence of the method of propulsion as well as
cockpit features designed to ensure crew survival.
3
UNCLASSIFIED/fFOA: OFFICIO la Plili Oralla¥
UNCLASSIFIED/ fFOR OFFI@IAI:: HSE OPtl::Y
As illustrated in Figure 2, when planning for breakthrough flight, there is no need to
constrain designs to match the legacy conventions derived from prior vehicles. In the
case of both the airplane and the helicopter, the control inputs available to the pilot are
specific to the mechanisms of the control surfaces. When projecting breakthough flight,
it is assumed that the controls will be tailored to match the natural characteristics of
pilots, and the propulsion system will be designed to perform accordingly.
4
UNCLASSIFIED/fFOA. OFFICIO ls. Plili Olhlls.¥
UNCLASSIFIED/ ,'FOR OFFI@IAL WSE QptLY
2A
28
2C
Figure 2. Comparing Conventions of Aircraft Motion. [Cred it : A. Szames]
5
UNCLASSIFIED/fFOA: OFFICIO la Plili Oralla¥
UNCLASSIFIED/ ,'FOR OFFI@IAL WSE QptLY
To make t his easier to grasp and to provi de a provisional co ncept , imagine tha t t he
vehi cl e is partit ioned into concent ric sections as shown in Figure 3. The central vol ume
is for the crew, where it is required that t he gravitational and inertial forces be
sustained within su rvivable levels. The inner she ll, or inner hull, su rround in g that reg ion
conta ins wha t ever devices provide that safe environment. The out er shell conta ins the
propulsion devices that induce the desired motion of the craft relative to the externa l
space. The reg ion between t he two hull shells is a provisional separation for ana lyzing
the int eraction between those two fu nctions.
Coordinate system of the Crew cabin where inertial
externa l environment and gravitational forces
are maintained at normal,
safe conditions
Outer shell whose
propulsion interacts with provides a safe internal
externa l environment force environment
Figure 3. Necessary Distinction Between External and Internal Force Environments. [ Grap hic: A. Szames]
For analytica l purposes, it is advant ageous to consider these volumes and control
surfaces (the hu ll shells) as separate and t hen use t hem to define boundary cond itions .
I n addition to its utility for assessing future cockpit designs, t his multisectioned vehicle
baseline is valuable for gedanken experiments about revolutionary propulsion concepts .
Why This Is Odd
Conventionally, gravitationa l and inertial effects permeate through everyth ing , so the
notion of having different conditions inside and outside of the craft runs contrary to
6
UNCLASSIFIED/fFOA: OFFICIO la Plili Oralla¥
UNCLASSIFIED/ ,'FOR OFFI@IAI:: ~SE OPtl::Y
experience. If the gravitational environment outside the craft is 1 g, that same 1 g is
expected inside as well. Similarly for accelerations, the entire mass of the vehicle,
including its occupants, will experience the same inertial reactions as the vehicle
accelerates.
Upon the advent of breakthrough propulsion, mastery over gravitational and inertial
forces will have been achieved. This implies, for example, that it is possible for a vehicle
to accelerate at extreme g's while its crew remains within survivable limits or that,
while cruising in deep space (absent of any acceleration or gravitational field), the crew
can enjoy the familiar, constant 1 g upward.
Because such possibilities run so contrary to established experience, it is difficult to
comprehend how such things can be achieved and then contemplate the consequences
that these advances impose onto other systems of the vehicle-in this case, how they
affect cockpit designs. Not all known approaches to propulsion physics evoke the need
for a double hull. 2 Versions that simply suggest a new thrusting mechanism and
reaction mass would only need the double hull if also addressing how to provide a safe
acceleration environment for the crew. As stated earlier, however, the most significant
possible impacts are considered for this study. Therefore, two examples are described
next for how breakthrough propulsion would require this provisional double-hull
configuration.
Why Double-Hull Needed: Example 1 (Warp Drive)
The Alcubierre warp drive, which uses the physics from the Riemannian geometry of
Einstein's general relativity, creates a "warp bubble" around the cralt, and then this
bubble of space-time is moved through the surrounding space-time . This effect is
created (in theory) by expanding space-time behind the vehicle and contracting space
time in front. The vehicle within the bubble feels no acceleration forces. As illustrated
in Figure 4, 3 the high peaks represent expanding space-time, while the low peaks
represent contracting space-time. Note that the inner region is flat (meaning that the
vehicle does not experience any acceleration forces), that the region far from the
propulsion effect is also flat, and that these two regions are separate.
7
UNCLASSIFIED/fFOA. OFFICIO ls. Plili ONls.¥
UNCLASSIFIED/ ,'FOR OFFI@IAI:: ~SE OPtl::Y
Figure 4. Warp Drive. Taken directly from the Frontiers book, this image has become the iconic representation
for a warp drive : the "York Extrinsic Time Plot."
In theory, the outer shell is presumed to create the propulsive effect of warping space
time outside the craft without affecting the inside. In short, the Alcubierre warp drive
creates a separation of space-time environments inside and outside of the craft,
although the exact details remain uncertain.
Although there is no explicit function for the inner hull in this situation, this Alcubierre
warp drive at least illustrates the concept of separation of these outer and inner
environments. When planning future cockpits, the outer and inner inertial frames need
to be treated as two distinct zones. The physics related to such considerations is still
evolving 4 and beyond the scope of this report.
Why Double Hull Needed: Example 2 {Field Space Drive)
Another class of conceptual propulsion is a "field drive"-a subset of "space drives"
where a spacecraft is propelled " ... using only the interactions between the spacecraft
and its surrounding space ... " 5 Instead of using the Riemannian geometry of Einstein's
general relativity, these approaches use the physics of fields and scalar potentials. 6
While several variants exist, the "Bias Drive" concept is selected here to illustrate the
relevance of the double-hull configuration, specifically in the context of modifying the
scalar potential that defines an inertial frame. By altering the properties of the
surrounding inertial scalar, a gradient in that scalar is induced which, in turn, induces
gravitational-like forces on matter located in that gradient.
8
UNCLASSIFIED/fFOA. OFFICIO ls. Plili ONls.¥
UNCLASSIFIED/ fFOR OFFI@IAI:: HSE OPtl::Y
Figure 5 represents one version of this effect/ where the vehicle and its contents would
be located at the steep gradient and therefore would jointly experience acceleration
forces. Taken directly from the Frontiers book, this image represents what would
happen if it were possible to asymmetrically modify Newton's gravitational constant to
induce gravitational gradients that would then, in turn, accelerate the vehicle. Despite
the similarity to the distortions in the warp drive (Figure 4), these surfaces represent
scalar potentials of gravitational fields. Figure 6 is a modified version of this where the
double-hull configuration of Figure 3 is imposed, along with the condition that the inner
region remains unaffected. In Figure 6, the locations of the inner and outer shell are
identified on the figure. The notion of the gravitational bias drive has been modified
here to illustrate the concept of having two separate zones of inertial and gravitational
forces. In this case, the plotted surface represents a scalar potential of an inertial
frame, where a gradient has the same effect as a gravitational field. The smaller central
flat area is the inside of the vehicle where no acceleration forces are felt. The outer
edges of the diagram are also flat, representing the unaffected space sufficiently far
from the propulsive effect. The distorted regions in between represent the effects of
both the outer and inner hull shells. The outer hull shell induces a gradient that propels
the vehicle, and the inner shell acts to prevent those distortions from reaching the crew
cabin. It should be emphasized that these notions are at the level of thought
experiments, as opposed to being mature theory.
a) Multiplicative modification, B, Eq. (39a) b) Exponential modification, b, Eq. (39b)
Figure 5. Hypothetical Gravitational Bias Drive.
In short, this Inertial Frame Bias Drive has affected the space both outside and inside of
the craft to propel the veh icle and to keep its crew isolated from the resulting
acceleration forces. For example, if the outer hull creates a 10-g field outside the craft,
the inner hull would compensate to create an opposing field such that the crew cabin is
free of the 10-g acceleration forces. It can, therefore, be speculated that-if such field
affecting physics is discovered-the inner shell could create a 1-g field when the craft is
coasting in 0-g deep space.
9
UNCLASSIFIED/fFOA. OFFICIO ls. Plili Olhlls.¥
UNCLASSIFIED/ ,'FOR OFFI@IAL WSE QptLY
Outer Hull Inner Hull
Crew Safe Zone
Figure 6. Inertial Frame Bias Drive and Vehicle Zones. [Credit : M. Millis]
To be explicit, the physics and engineering to create such situations do not yet exist.
The related physics can be categorized as still being at steps one and two of the
scientific method: defining the problem and collecting data. 8 Among many other issues
eluding discovery and resolution, major issues include momentum conservation, the
role played by inertial frames, and methods to affect gravitational and inertial
properties of matter and space.
Secondary Consequences
Pertinent to cockpit design, the normal sensations of motion inside the cockpit will likely
not be the same. In contrast to the advantage of shielding the crew from harsh
maneuvers, this shielding removes sensations of motion (seat-of-pants feeling) that
pilots use to help judge the motion of their vehicle. This detriment is compounded by
the likelihood of inducing motion sickness, since the visual cues of the vehicle's real
motion will be different from that felt by the pilot. A difference between visual and
vestibular cues is a cause of motion sickness. The option of allowing a certain portion of
the vehicle's g-loading to be transferred to the cockpit can be considered as a
mitigation strategy. Accordingly, cockpit controls to affect such changes are required.
Also, it is likely that this double-hull notion would prevent direct visual contact between
the occupants and the environment outside the vehicle, or perhaps distort such visual
cues beyond easy interpretation. In other words, do not expect windows. Without the
famil iar visual and vestibular cues directly available to the pilot, it becomes vitally
important for the cockpit displays to provide re liable and instinctive cues for the pilot to
aptly judge the position, orientation, and motion of the vehicle.
Mixed Operational Regimes
A major desirable feature sought from propulsion breakthroughs is the ability to move
from the surface of the Earth directly into space. This implies that the veh icle's displays
and controls must readily encompass motion near the Earth's surface, ascent into space,
10
UNCLASSIFIED/fFOA: OFFICIO la Plili Oralla¥
UNCLASSIFIED/ ,'FOR OFFI@IAI:: ~SE OPtl::Y
transitions into and out of orbits, and long-duration sustained cruising in a 0-g
environment.
As alluded to earlier, this deviates from prior displays where the Earth's gravitational
field is available from which to gauge orientation. Similarly, the notion of an altimeter
takes on a whole new meaning in this context. While visual cues for "up" are
instinctively clear near the surface of the Earth (or even in closed rooms where 1 g is
present), for a true breakthrough vehicle, these will be special conditions amongst a
greater span of possibilities.
A particular consequence of these added operational regimes is that unfamiliar
situations are presented that must be made easy for the pilot to comprehend. Human
instincts of motion and perception are honed from living in a 1-g environment with the
majority of motions constrained to the (comparatively) two-dimensional ground. Also,
lacking eyes in the back of our heads, our natural sense of attention is focused forward.
While these instinctual characteristics serve well in travel near the ground, they do not
apply to orbits or to deep-space flight.
Orbit
Orbits around the Earth-or any gravitating body, for that matter-present stable,
constant energy situations. Orbits are convenient parking locations. A vehicle does not
need to expend energy to stay in orbit indefinitely (unless drag forces from the
atmosphere or long extensions of the vehicle come into play). Orbits, therefore, are
common trajectories to select when loitering near gravitating bodies. But so far in the
course of human evolution, developing an innate sense of placing a vehicle into an orbit
does not exist. Although a human can instinctively run at just the right speed and
direction to catch a ball thrown toward them, such natural instincts do not apply to
placing a vehicle in orbit. Therefore, display systems will be required to provide readily
interpretable cues for the pilots to transition into orbital flight. This implies presenting
the natural relations between orbital altitude and orbital speed. This challenge is
compounded since such cues must naturally blend with the motion cues used when
flying near the surface.
Deep-Space and Interstellar Flight
Deep-space flight adds yet another challenge; namely, the almost total absence of
familiar cues for motion, position, and orientation. Given the extremely large distances
between astronomical objects and that relativistic effects do not become significant
(>1% distortions) until reaching beyond 10% of light speed, the view outside the craft
will appear stationary-even when traveling at 60 million miles per hour (9% c). The
display systems that are tied to the navigation references (to be discussed later) must
convey motion to the pilots in a natural manner despite the absence of familiar human
cues.
Compounding the absence of a sense of motion, there is an absence of orientation.
There is no dominant direction for "up" during deep-space flight. If some form of
artificial or synthetic gravity is provided for long-duration crew health, then that
internal 1 g will create the most dominant sense of "up" for the crew, and the display
11
UNCLASSIFIED/fFOA. OFFICIO ls. Plili ONls.¥
UNCLASSIFIED/ ,'FOR OFFI@IAI:: ~SE OPtl::Y
system that conveys the spacecraft's orientation relative to the external space will have
to be clea r enough to overcome this prejudicial sense of orientation.
Notice, for example, that in almost all science fiction stories, spacecraft move laterally
(forward) relative to the veh icles' internal sense of "up" {Figure 7). Motion along the z
axis is seldom mentioned. Althoug h this is a natural extension of how we move relative
to the surface of the Earth, it is not the only scenario. In contrast, consider a rocket
whose 1-g orientation is aligned with its major axis of motion. Th is is a consequence of
its propulsive thrust. In other words, at least two conventions for direction during deep
space flight are possible : the notion of lateral motion across a landscape (where the
internal 1 g is at right ang les to flight), or vertical motion with an astronomica l range
(where the internal 1 g is coincident with the direction of flight).
Conven iently matching film studio cond itions, the interiors of fictional spacecraft
provide a comfortable 1-g environment for the crew. They also fo ll ow the terrestrial
convention of motion: their major direction of motion is forward (a lateral motion),
even though they are experiencing an acceleration force of 1 g upward (their internal,
synthetic gravity). These two directions, up and forward, are at a right angle. In
contrast, the thrusting direction and the internal g-axis of a rocket are in the same
direction. The choice of orientation for real deep-space motion is a subject for further
study.
FORWARD
(Externally)
Figure 7. Typical Science Fiction Orientations. [Images: A. Szames]
Since propulsion breakthroughs have not yet been discovered, there is no way of
knowing if the propulsion methods themselves will dictate the choice of orientation.
Therefore, to plan for the uncertain future, this is a choice worthy of deeper study. Is
the natural human instinct for forward-dominated motion a better human-machine
interaction than the upward-dominated motion that might be dictated by the propulsion
method? Such an assessment must also consider how well the convention works when
transitioning from deep-space flight into orbit, then landing, and then back again to
deep-space flight. Once any convention is set into place, it will be difficult to change
later.
12
UNCLASSIFIED/,<FOA. OFFICIO ls Plili ONI.¥
UNCLASSIFIED/ ,'FOR OFFI@IAI:: WSE ONl::Y
Crew Size Considerations
The last aspect to t ake into account as a conseq uence of m ixed ope rati onal regimes is
that of the crew size. For short-durati on missions (less than a few hours), it is
reasonable to conceive of vehi cles with only one pil ot. For more complex missions,
add it ional crew will be required, and thus addit ional displays and controls specific to
thei r tasks wil l be req uired . Finally, for long-durati on missions, sufficient crew will be
required to carry out its mission and maintain optimal vehicle performa nce. These
changes-for accommodating the roles and responsibilities of crew in relation to the
overall mission-are likely to be the same as those disti nctions in trad itional vehicles
(e.g. , cars versus cr uise ships). Those changes typica lly incl ude a hierarchica l
orga nization, wh ich is independent of the issues of propulsion physics .
Essential elements wi ll include monitoring and controll ing the 1-g internal life-support
environment as wel l as ensuri ng the long-t erm health of t he crew .
Full Span of Speeds
I n add ition to inertial effects previously addressed, t he implicat ions due to high speed
remain. Accommodating the reaction t ime of the pilot is critical. The extreme high
speed of breakthrough spacecraft will demand that aut omated flight controls take
precedence over the pilot's manual flig ht control.
Automated controls for aircraft and even for automobiles are an ever-improving
technology. For brea kthrough fli ght, these technolog ies will be mandatory and will also
have to include options for maneuvering near ground, into orbits, and t hrough deep
space. This should come as no surp rise, since the adva ntages of having automated
flight controls warrant their use even if pilot reaction times were not an issue.
Table 1. Comparing Reaction Time to Distance Traversed at Various Speeds 1
Speed Distance Traversed in l Second
mph km/h C Feet Meters Miles Km
Walking 2 3 3 1
Driving Around Town 40 64 60 18
Commercial Air Flight 500 800 730 220
Hyperson ic Flight 4,000 6,400 0.00001 5,900 1,800 1 2
Low Earth Orbit 17,500 28,000 0.00003 26,000 7,800 5 8
Deep-Space Probe 35,000 56,000 0.00005 51,000 16,000 10 16
60 97
Non relativist ic Flight 0.09 89 Million 27 Million 17,000 27,000
Million Million
400 650 110 180
Relativist ic Flight 0.60 590 Mi llion 180 Million
Million Million Thousand Thousand
1 The distances traversed while waiting for the pilot to react are reasonable for speeds slower than hypersonic
fl ight. If traveling at hypersonic speeds near the ground, however, the situation is different. At some point,
regardless of the skill of the pilot, an automated system will be needed . Also note the huge disparity between the
fastest achieved speeds (deep-space probe) in comparison to nonrelativistic flight. This disparity of three orders of
magnitude is a clear statement about the state of our technology when contemplating deep-space flight.
13
UNC LASSIFIE D/fFOA. OFFICIO ls. Plili ONls.¥
UNCLASSIFIED/ ,'FOR OFFI@IAI:: ~SE OPtl::Y
660 1.07 180 297
Extreme Relativistic 0.99 970 Million 270 Million
Million Billion Thousand Thousand
670 1.08 190 300
Light Speed 1 980 Million 300 Million
Million Billion Thousand Thousand
13 22
Faster Than Light? 20 202 Billion 6 Billion 4 Million 6 Million
Billion Billion
Table 1 is designed to put a pilot's reaction time into perspective; it compares distances
traversed during the one second it takes the pilot to scan and comprehend his displays
("dwell time") and then react. 9 In addition, it will take time for those commanded
changes to take effect, but those durations are not known. The distances shown in the
table are those traversed before any corrective actions are initiated. If these distances
are determined to be excessive, then automated flight controls are mandatory.
Another aspect resulting from the effects of ultrahigh vehicle speed is the so-called
"relativistic twin paradox. 1110 Because of relativistic effects, there will be a mismatch
between the time measured aboard the craft and that measured at its base of
departure. The equations to track this situation are well established. 11 The challenge is
how to present this information so that both the crew and the mission personnel at the
base can easily comprehend the implications.
More provocative than the implications of relativistic speeds is the possibility of faster
than-light (FTL) travel. Beyond the perplexing issues of causal violations and closed
time-like curves inherent with all FTL notions to date, 12 there is the question of tracking
position, orientation, and motion when beyond light speed.
It is reasonable to assume that when a vehicle is traveling FTL, the normal flow of
electromagnetic waves (i.e., light) to and from the craft will be cut off. To better
visualize this, consider the Doppler shifts as a vehicle approaches light speed. The
colors of light heading into the flight path will be shifted to such a short wavelength
that it will cease to be detectable. Similarly, the light approaching the rear of the craft
will red-shift so much that it also ceases to be detectable. Again, do not count on
windows.
Navigation References
The main difference between navigating with existing vehicles and breakthrough
vehicles is that the breakthrough vehicles will have to navigate in deep space and
around other astronomical bodies where GPS systems and location beacons do not exist.
Another major difference is that the physics of the propulsion methods might distort or
block information that is traditionally used for navigation.
Inertial Navigation (Acceleration Measurement)
In inertial guidance systems, accelerometers and ring laser gyros accurately track the
changes in the vehicle's motion (lateral and rotational accelerations). These signals are
integrated to keep track of position by evaluating changes in both velocity and
acceleration.
In the case of the double hull, where the inertial effects might be different inside of the
craft, these tools become more diffi cult to apply. If we assume that the physics and
14
UNCLASSIFIED/,<FOA OFFICIO ls Plili ONI.¥
UNCLASSIFIED/ ,'FOR OFFI@IAL WSE QptLY
technology for manipulating inertial fields ( or for warping space-time) can accurately
track these effects, then that knowledge may compensate to keep these tools viable.
Design of future guidance systems must address this issue.
Absolute Velocity - Universal Speedometer
Conven iently, nature provides another reference frame for deep-space navigation. The
cosmic microwave background is a reference frame against which velocity can be
measured relative to the mean rest frame of the universe. By comparing fore/aft
Doppler shifts relative to th is highly isotropic and homogeneous rad iation, velocity
measurements can be derived. For example, the net velocity of the Earth's motion
relative to this background has been measured to be 365 km/s. 13 However, the cosm ic
microwave background will not be detectable at FTL speeds.
As illustrated in Figure 8, although many of the pictures of the cosmic microwave
background radiation remove the prominent dipole moment shown in this graphic (the
major color difference), it is precisely this dipole-the difference between fore/aft
Doppler shifts-that provides a navigation reference for deep-space flight. The
projection of this image is a spherical shell that has been opened and flattened. The
Doppler shift corresponds to the Earth's motion of over 1.3 million km/h relative to the
mean rest frame of the universe. The Earth moves in the direction away from the red
and toward the blue.
Figure 8. Cosmic Microwaves as Universal Motion Reference Frame. [Cred it : NASA]
Position-Reference Star Trackers
For deep-space flight, the star trackers that have been developed for existing
spacecraft may still prove viable, new instrumentation will probably be required. Given
the enormous expanse of space, the apparent locations of stars will not vary that
much .14 Even those that do appear to move-our closest stars-are known well enough
so that software can take into account how those positions will change as the vehicle's
position changes. Due to Doppler shifting, as noted previously, checking positions
relative to the stars will only be possible at sublight speed.
For speeds approaching light speed, corrections will be required for relativistic effects.
Such effects will probably not become apparent until traveling well beyond about 9% c,
15
UNCLASSIFIED/fFOA: OFFICIO la Plili Oralla¥
UNCLASSIFIED/ ,'FOR OFFI@IAI:: ~SE OPtl::Y
which is a speed that is still three orders of magnitude beyond the highest speeds
achieved to date.
Another modification for star trackers will be required for FTL travel. In essence, with
FTL flight, the vehicle arrives at the destination ahead of time-in an unfamiliar way. To
understand this, recall that all information we see from the cosmos is old. Those images
have taken a while to reach us, and the reality at their point of emission has continued
forward in time. For example, when we see sunlight, the image is more than 8 minutes
old. The images we see from Alpha Centauri show what it looked like over 4 years ago.
Thus, if we could zip to Alpha Centauri instantly, over 4 years of time would have
elapsed since we last looked at it. Alpha Centauri's condition will be a surprise upon
arrival.
Therefore, any star tracker to accompany FTL flight must take into account the
trajectories of astronomical objects so that their positions can be accurately predicted
to correspond to the correct time of arrival in both spatial and temporal coordinates.
There is no known precedent for this situation.
In support of the forgoing discussion, we are speculating that heretofore unknown
advances in physics regarding the quantum vacuum and the nature of inertial frames
will result in new motion-detection technology. In researching future propulsion
breakthroughs, the utility of sensing and affecting such phenomena is pertinent.
Compilations of Implications
The following list is a compi lation of the characteristics discussed in this section about
the possible features associated with breakthrough flight. While the list is admittedly
incomplete, it conveys the most significant differences compared to conventiona l
methods of flight.
• Six degrees of independent motion/orientation:
- Translational motion: fore/aft, left/right, up/down.
- Rotational (orientation): pitch, yaw, roll.
• Distinct inner and outer environments for inertial and gravitational forces.
• Speeds encompassing zero, subrelativistic ( <0.1 c), relativistic (0.1 c ~ v < 1.0 c),
and beyond light-speed, yet expecting a travel limit of about a 100-light-year radius
around the Sun.
• Three flight regimes:
- Near the surface of gravitating body (where gravitational direction provides
natural orientation).
- Orbits around a gravitating body (where cues for entering orbit are required for
the pilot).
- Deep-space flight (without obvious orientation cues or obvious sense of motion).
16
UNCLASSIFIED/fFOA. OFFICIO ls. Plili ONls.¥
UNCLASSIFIED/ fFOR OFFI@IAI:: HSE OPtl::Y
• Navigational information sources:
- Position:
• Master reference taken relative to starting position (Sun-Earth system).
• Current location taken from the following:
o Star tracker:
• Modified to handle 3D database of star locations for deep-space
motion (yet less than 100-light-year radius around the Sun).
• Predictive trajectories (to extrapolate positions for FTL travel).
• Note: Can only take star tracker readings at sublight speed.
o First integration on measured velocity and relative to point of
departure.
o Second integration on measured accelerations since point of departure.
- Velocity:
• Directly measured from cosmic microwave background Doppler shifts,
where velocity is relative to the mean rest frame of the universe.
• First integration on measured accelerations since point of departure.
- Accelerations:
• Linear:
o Accelerometers with corrections calculated based on the influence of
the propulsion methods that affect gravitational and inertial forces.
o Differentiation of velocity changes as measured using the cosmic
microwave background.
• Rotational:
o Gyros (e.g., ring laser gyros) with correction inputs from the
propulsion methods that affect gravitational and inertial forces.
o Orientation as inferred from star tracker measurements.
17
UNCLASSIFIED/fFOA. OFFICIO ls. Plili Olhlls.¥
UNCLASSIFIED/ ,'FOR OFFI@IAI:: WSE ONl::Y
Chapter 2: Human-Machine Interface Lessons
Over recent decades, substantial improvements have been made to human-machine
interfaces. 15 Most of this progress relies on better accommodating the norms and limits
of human perception-lessons that do not change even when vehicle characteristics
change. These lessons are reviewed in this chapter and then applied in the conceptual
design offered in the third chapter. Examples of such characteristics include reaction
times, tunnel vision under stress, instinctual association with position, interpretations of
displayed colors, and lessons learned from interactions with display and control
technologies.
Recent progress on augmented rea lity displays, 16 voice control, 17 gesture-based
computer inputs, 18 and brain-machine interfaces (BMis) 19 are also considered. In this
study of far-future possibilities, these technologies are assumed to have reached full
maturity. Instead of going into the details of their status, only their implications will be
addressed here.
One exception was made when considering emerging technologies-specifically the
notion of modifying humans for breakthrough flight. This exception includes brain
implants for BMis and reengineering humans (transhumanism) to adapt to new
requirements. 20 Rather than requiring humans to be reengineered for breakthrough
flight, this study focuses on adapting the cockpit to address natural human
characteristics. This forces attention on the cockpit design requirements.
Numerous references about human factors were consulted, focusing on those details
most relevant to this study. Since similar assertions were echoed in many of these
references, it is not always clear how to trace a given assertion to a specific reference.
Instead, an annotated bibliography is included at the end of this report that has short
descriptions of each reference.
HUMAN PERCEPTION NORMS
Physical Object Analogs
Human interpretation mechanisms are rooted in the paradigm of a physical
environment. Mimicking a physical environment in a display and control system
enhances comprehension and allows features to be recognized with less effort t han
when translating dial s, bar graphs, or alphanumeric displays. 21 Th is not only pertains to
perceptions of motion, but also to t he comprehension of a vehicle's operation:
understanding its lim its, supplies of consumables, malfunction modes, and other
parameters .
Accordingly, humans naturally remember where to look for a particular piece of
information or what direction to flip a particular switch. Humans are also adept at
subconsciously applying models of social behavior and causal events. Hierarchies,
similar to societal organizations, offer a natural model with which to categorize systems
and subsystems. Causal relations (cause leads effect) match well with procedures and
operational flow diagrams. For more abstract concepts and complex data sets, a
combination of hierarchical and causal relations can be used, typically taking the form
18
UNCLASSIFIED/fFOA. OFFICIO ls. Plili ONls.¥
UNCLASSIFIED/ /FOR OFFICIAL USE ONLY
of conceptual maps. Numerous templates for these tools are readily available and
many are adaptable to gesture-based interaction .22
Color
Color is convenient for labeling different categories of information, providing status
indications, and for adding redundant (corroborating) information to minimize errors.
Humans mentally process color information first and do so more accurately and with
less effort than when distinguishing shapes or alphanumeric indicators. The upper limit
on the recommended number of colors to simultaneously display is only about 4 to 12
colors. To augment this number, it is acceptable to adjust the saturation or brightness
of a given color to represent gradations, such as terrain height or the criticality of a
variable. 23
Although research has not progressed to the point where absolute recommendations
can be made for the use of colors, the tripartite system is a widely recognized and
easily discernable status indicator:
• Red = danger.
• Yellow = caution.
• Green = safe to proceed.
Conveniently, fewer pilots have colorblindness than the general public, and thus color
coded displays can be used more effectively than with the general public (data: 8% of
males and 0.4% of females are colorblind to red-green or blue-yellow distinctions). 24
Other lessons regarding the use of color include the following : 25
• Use strong colors sparingly: strong colors draw attention, and too many of them can
overstimu late the user.
• Yellow is a rare color since it is simultaneously soft and intense.
• The color of objects is more discernable than the color of text or lines.
• Use soft colors (grays, pastels) for backgrounds and large areas.
• A good color choice is one where that color is not conspicuous.
• Use soft contrasts or graduated contrasts between areas, since hard contrasts can
appear to vibrate.
• Avoid having the color white next to strong colors since it is too much of a contrast.
• Avoid framing a box of text since that creates clutter. Instead, place the text in a
box with a different fill color.
• If needed to strengthen boarders between softly colored areas, frame the area with
a darker shade of its fill color.
19
UNCLASSIFIED/fFOA. OFFICIO ls. Plili ONls.¥
UNCLASSIFIED/ ,'FOR OFFI@IAL WSE QptLY
Fields of View
There is a difference between what humans are physically capable of seeing and where
they naturally concentrate their attention. Using a reference point that is stra ight
ahead and level with the eyes, the normal full field of view extends laterally (left/right)
±100°, upward about +60°, and downward about -75°. Of course, turning the head
can extend the lateral reach directly behind, but that rearward view would be in the
edge of periphery vision. This full span, however, is not where humans normally direct
their attention.
With the head in a fixed position, the normal field of view spans left/right ±100°. The
periphery is most sensitive to motion even when discrete images cannot be resolved.
The region shown that spans roughly ±60° is the area that can be easily scanned by
moving the eyes and whose information can be mentally processed in parallel. A much
narrower field, about ±6 °, is where humans can discern details and begin processing
information serially. This zone can be aimed anywhere in the normal field of view.
Finally, the region of focus where alphanumerics can be read is only about ±2°, which
corresponds to only one square inch at a distance of 2 feet. Another characteristic of
human vision is the tendency to fixate in the upper right corner of a given display. In
the figure insert, the percentages shown refer to the proportion of total time that the
eye tends to fixate on those regions.
Figure 9. Human Fields of View. [Graphic: A. Sza mes]
20
UNCLASSIFIED/fFOA: OFFICIO la Plili Oralla¥
UNCLASSIFIED/ ,'FOR OFFI@IAL WSE ONLY
Peripheral Vision
Peripheral vision has been used with some success to display rates of change and
artificial horizons in aircraft. Evidence indicates that peripheral vision can process
spatial information in parallel without appreciable mental attention. Also, evidence
indicates that peripheral spatial cues (e.g., artificial horizon laser trace) may still be
subconsciously processed during stress-induced tunnel vision, even though the pilot is
no longer consciously noticing it. 26
Attention
In the absence of stimuli, visual attention is spread evenly across the full field of view,
and that information is processed subconsciously in parallel. But in the event of motion
or noise, visual attention aims toward those changes, and then that information is
processed serially. In t he context of cockpits, this means that all the panels and
windows that are normally in the field of view are processed subconsciously in parallel,
and a change in any one of those will be noticed, thus drawing attention to that change.
Once attention has been triggered, the information is processed more serially.
Blinking lig hts are a common way to draw attention. Sound can also be used, and the
combination of sound and lig hts is common ly used in malfunction enunciator panels. It
is possible, however, to saturate the pilot with too many blinking lights and sounds.
Although firm values are not established, it is recommended to keep such functions to a
minimum-preferably tied to the highest-priority status indications.
Another method to draw the attention is through physical feeling. Vibrations or a
change in feel of the vehicle will get the attention of the pilot, and with experience, the
correlation between physical sensations and the status of the vehicle can become
second nature. Historica lly, there are many instances where the pilots were innately
able to sense changes in operating condition of the vehicle just through feel.
In addition to naturally created sensations, having deliberate vibrations built into t he
seat is another option for sending information to the pilot. Force-feedback controls
have also been found helpful, where the degree of resistance or vibration fed back
through a control (e.g., joystick and peda ls) provides interpretable information that can
be mentally processed in parallel.
Upon the advent of control over gravitational and inertial forces, it will likely become
possible to deliberately provide the pilot with vestibular cues-mimicking inertial
accelerations in association with the external conditions, but at survivable levels.
DESIGN FOR STRESS
The most important time for the pilot-machine interface to work optimally is in
moments of crisis. Thus, as a starting point for cockpit design, it is best to focus on the
highest-priority information and controls and to present those displays and controls in a
manner that accommodates human norms during stress. 27 Accordingly, this section
covers human limits and errors and advice for providing alarms and response options.
21
UNCLASSIFIED/ fFOA. OFFICIO Is. flili Ol'lls.¥
UNCLASSIFIED/ ,'FOR OFFI@IAL WSE QptLY
Dwell and Reaction Time
It takes about 0.4 to 0.6 seconds of dwell time at a particular display to extract the
necessary quantitative information and at least 0.125 to 0.2 seconds for a qualitative
recheck to reaffirm the reading has not significantly changed . In addition, the pilot
needs another 0.125 to 0.2 seconds to act on that information. 28 Taken together, this
creates a total response time of 0. 7 to 1.0 seconds between first looking at a display
and commanding the appropriate response.
As an aside, displays whose update rates exceed this dwell time cannot be accurately
read. This means that displays shou ld be slowed down to the rate at which humans can
absorb their information, rough ly a half-second.
Tunnel Vision
While under stress, humans t end to narrow their visual attention, often fixating on a
single central display or task : the greater the stress, the greater the narrowing .
Humans are oblivious to this effect as it is happening. (As an aside, hypoxia - breathing
insufficient levels of oxygen-induces the same effect and can be used to simulate this
cond ition during train ing.) Periphera l vision is ignored, although some evidence
suggests that spatial peripheral cues are subconsciously retained. This tunnel vision
tendency cannot be prevented, but can be accommodated by providing the most critical
information on the central display in a natural symbolic format. 29
Forgetful Visual Scanning
Humans tend to lose track of when they last looked at a particular area of information,
sometimes forgetting to recheck parameters when needed. 30 This is where automated
checklists can help, 31 as well as vehicle management systems that process the vehicle's
situation and then recommend the best corrective measures.
Limiting Options
Humans tend to be able to retain only about 3 to 10 different items in short-term
memory. Some studies focus on seven items as the optimum. Thus, it is recommended
in quick-selection menus, or when designing hierarchical categorizations, to have no
more than four to seven items per level. For groupings of information that are not
needed during critical moments, these constraints can be relaxed, but with the added
consequence of requiring significantly more browsing time.
Adaptive Display Errors
In computer displays having mu ltiple layered windows, or where the display changes in
different situations, it is common that a user will lose track of how their current display
image relates to the whole system. 32 Th is problem is called "getting lost" or referred to
as a "keyhole" error. To prevent this error, it is best to simultaneously display some
schematic indicator of where the user is in the system. Th is requires a pictorial
representation of the relations of the system's operational windows . This situation is
consistent with the evidence that humans tend to rely on a physical model for where to
22
UNCLASSIFIED/fFOA: OFFICIO la Plili Oralla¥
UNCLASSIFIED/ ,'FOR OFFI@IAL WSE QptLY
look for information rather than being proficient at remembering a sequence of steps
from which to retrieve information.
In systems having different operating modes, a common error is for an operator to
execute a command sequence that is inappropriate for the mode they are currently
using but entirely correct for a different mode. 33 This type of error is called a "mode
error." An example of this is when a pilot enters a new heading for the autopilot to
follow when the plane is not in autopilot mode. To prevent this error, it is advised to
have the most critical operating modes as fixed, physical displays.
Other Distractions
It is important to remember that the cockpit might not always offer a smooth,
distraction-free ride. Buffeting can cause a finger to press the wrong button (or a
gesture-based command to misdirect), or the eyes might not be able to resolve a
particular value. Excessive use of audible alarms and blinking lights can saturate the
pilot. Other activities or distractions available to the pilot must be taken into account so
that the most critical functions are easy to find and operate, including sufficiently large
buttons and text.
Alarms and Responses
Traditionally, physical enunciator panels combined with audible alarms and blinking
lights were used to highlight malfunctions. In addition to fixed enunciator panels, more
complex systems can now computationally analyze a number of variables and only
present the most pertinent values and alarm states.
DEVICES TO CONVEY IN FORMATION
Observation and interpretation of displays is always secondary to the primary task of
actually operating the system. Thus, it is important that displays be designed to first
serve the user and to take on as much of the information-processing burden as
possible. Also, it is suggested that the displays and control input devices should be
designed according to the operator's preferences, as opposed to the more common
practice of designing based on the system engineer's expectations. The following
paragraphs describe lessons learned regarding various methods of conveying
information to the pilot. 34
Fixed and Adaptive Displays
Fixed displays, such as the gauges of older aircraft, do not change the type of
information they display nor do they morph their format. These can be dials, bar
graphs, an artificial horizon, or simple indicator lights. Such fixed displays can be
projected with computerized screens where several interrelated values can be combined
into a single, computed value. Adaptive displays, on the other hand, can change their
formats or change the topics displayed to fit operational situations or individuals. Both
have their respective optimum uses.
During the advent of adaptive displays (circa 1990s), they tended to be overused. The
advantage is that the information can be tailored to minimize the volume of information
displayed at any one time. The disadvantages are that such systems require more
23
UNCLASSIFIED/fFOA: OFFICIO la Plili Oralla¥
UNCLASSIFIED/ ,'FOR OFFI@IAI:: ~SE OPtl::Y
effort on the part of the operator and are more prone to mode errors and keyhole
effects, particularly during high-stress situations. It was also found that automatically
changing display formats added anxiety and mistrust of the system, because the user
was now burdened with the additional task of determining why the display just
changed. A survey of Boeing 757 and 767 pilots in 1989 revealed that over half felt
their workload had actually increased by the high levels of automation introduced into
these cockpits. In practice, users forced adaptive displays into fixed displays to improve
their utility. 35
The ultimate lesson is that the most critical displays should be fixed to take advantage
of the naturally efficient search method where humans use mental models that are
analogous to physical objects. For other functions that are less time-critical and where
further details are required (e.g., entering destinations and way points into a flight
plan), adaptive displays are more advantageous because they require less console
space. Other lessons include the following: 36
• Following the same recommendations for the individual elements of adaptive
displays that are given for graphical and alphanumeric display components.
• Matching the performance characteristics of the displays to the operator's own
internal model of the system, and they should be structured to accommodate a
user's knowledge.
• Packaging information into appropriate, meaningful clusters.
• Representing logical and causal relationships should be implemented.
• Using "fewer displayed variables with many states" is recommended over the display
of "many variables with few states." This necessitates arranging variables in a
hierarchy where the lower-level variables are combined into higher-level variables.
• Using color to improve the speed of human comprehension.
• Accessing back-up information should be easy (familiar procedure), and it should be
easy to browse through the system without disturbing its operation.
Virtual Displays and Augmented Reality
An extension of the adaptive screen is a virtual display where the information is
projected into a field of view without the need for a physical display screen. These can
function as adaptive displays or be used with gesture-based input systems.
Although far-future cockpit technology is still being researched, this study assumes it to
be fully matured, such that any information can be displayed clearly in the pilot's full
field of view. That being said, the other recommendations about accommodating
human norms and the lessons of adaptive displays should be heeded. By that, it is
meant that the critical information should remain consistent, and the functions that can
tolerate slower user actions can be accommodated with pop-up screens. Also, rather
than relying solely on a virtual display, the critical displays should still have a physical,
redundant set of displays.
24
UNCLASSIFIED/,<FOA OFFICIO ls Plili ONI.¥
UNCLASSIFIED/ ,'FOR OFFI@IAI:: WSE ONl::Y
A key feature of virtua l displays will be the inclusion of augmented reality. This means
that key elements in the field of view are highlighted with color or framing to draw
attention 37 to them. This includes adding obvious border lines to objects for which the
pilot needs to be aware . Similarly, a virtual display of the environment outside the craft
could be augmented to revea l cha racteristics outside the range of normal human vision
such as infrared and ultraviolet light, or objects too small or fast to normally be noticed.
Graphical and Alphanumeric Representations
Pictorial displays in combination with alphanumeric displays have been found to be an
effective way to convey information to a pilot. A pictorial representation of the item or
cond ition being controlled (maps, artificial horizons, graphical representations of vehicle
stores, and others) takes advantage of the interpretation paradigm of physical models,
and thus enhances comprehension and allows features to be recognized with less effort.
Although reading alphanumeric displays are more time consum ing and workload
intensive, they provide more accurate values and are more easily relayed verbally to
secondary users (i.e., the value can be read aloud). It has also been found effective to
place the alphanumeric values in the upper-right corner of the graphical display. Other
lessons include the following: 38
• Using consistent text, format, placements, axes, and other parameters. 39
Consistency has been found to be more desirable than optimized displays. 40
• Displaying parameters relative to their expected va lues rather than just displaying
the alphanumeric va lue. Some indication of the criticality of an off-nominal reading
also needs to be displayed.
• Using zero-value points as a reference and showing range settings on graphical
displays to indicate how a given value compares to the desired or pred icted value;
all ranges should be roughly the same size if possible.
• Displaying nonessential symbols as half-intensity helps declutter displays.
Enunciators
Historically, all the major alarm indicators for a system were grouped together into
what is called the "enunciator panel." Usually, this panel is an array of rectangular
lights with each representing a possible alarm or critical-state variable (e.g ., 5 x 5
arrays of 25 discrete alarm channels). Frequently, the lights use the tripartite color
convention, blink to alert, and are connected to an audible alarm. There is usually some
means to acknowledge the alarm and thus stop the distracting blinking and noise
without ca nceling the alert status indication (e.g., goes from blinking with audible alarm
to just lit in red or yellow).
Old hardware displays unintentionally maintained a manageable number of alarm states
as an inadvertent, but positive, consequence of the difficulty of adding enunciator
segments. With computerized systems, however, th is number can grow to be
overwhelming. Conversely, with computerized systems, analysis of vehicle operations
can reduce a large number of variab les into a composite key status variable for alarm
states and offer pre-determined options of emergency responses to the pilot. Hence,
the concept of an enunciator can be quite useful if following t hese recommendations:
25
UNCLASSIFIED/fFOA. OFFICIO ls. Plili ONls.¥
UNCLASSIFIED/ ,'FOR OFFI@IAI:: WSE ONl::Y
• Limit the number of alarms.
• Display alarms in a dedicated, predictable location.
• Link alarms to a pictorial representation of the system to help recognize root causes,
causal relations, and where to focus corrective action.
• Provide a means to acknowledge the attention-getting aspect of the alarm without
turning off its alert status indication.
• In the case of multiple triggered alarms, the system's most prominent display
should be the highest hierarchical alarm, the highest causal alarm, or the location
on which to focus corrective action.
• Link the alarm clearly to the control response options.
Checklists
Checklists are a standard and useful tool in the operation of vehicle systems. They can
be displayed on adaptive displays where the list corresponds to the vehicle's current
status (e.g., preflight readiness or postflight checks). Recommended features of a
checklist should include the following : 41
• Display the desired and current value with each checklist item.
• Require that buttons/switches have to be touched to acknowledge t hat each item
has been checked off. This helps avoid skipping items and helps the user keep a
sense of involvement in the process.
• Include a completion call at the end of the checklist.
• For long lists, subdivide using the following guides:
- List critical items first.
- Use geographical (i.e., physical location) flow or pictorial flow to help users
retain relation between the model of the system and the procedures being
performed in the checklist.
- Use parallel tasks between the onboard operation and the ground operations
to maintain fluency between pilot and mission control communications.
- Include buffers in checklists to provide recovery time for anomalies. Decouple
tasks if possible so that t he failure to meet a given checklist item does not
leave a parallel item in an open state.
- Standardize checklists within the system (assuming nested, hierarchical, or
multiple checklists) to minimize the mental burden necessary to extract
information when going from one format to another.
26
UNCLASSIFIED/fFOA. OFFICIO ls. Plili ONls.¥
UNCLASSIFIED/ ,'FOR OFFI@IAI:: WSE ONl::Y
DEVICES FOR RECEIVING PILOT COMMANDS
In much the same way that displays are configured to match the dominant norms of
human behavior, so too are the command functions. As evidenced by the gaming
industry, the motions of the pilot's hands-whether by a joystick or a Wii controller42 -
mimic the intended physical motions of the object under control. Some of these control
technologies are described below.
Physical Controls
Devices such as joysticks, toggle switches, thumb wheels, rotary switches, and even
keyboards will still be mandatory in cockpits of the future. This is based on needing
fixed locations for the most critical displays and controls. Additionally, tactile feedback
helps the pilot know that their command has been entered. In moments of crisis, a
human can react quickly to reach for just the right switch and detect the sensation
when that switch is flipped.
Joysticks take advantage of human nature, where hand motions mimic the intended
motions of the object under control. Joysticks and pedals with force-feedback or
vibration feedback add another element of information that humans can process in
parallel-feedback that would not be possible with virtual controls .43
Despite advances in other data-input technologies (e.g., voice), it is likely that there
will be times when a keyboard is required, but its routine use is not expected.
Keyboards are an efficient way to accurately enter alphanumeric data and especially
narrative text. Conversely, keyboard use is time consuming, physically requires a large
space (can be stowed, however), and is subject to errors during vibration or buffeting.
Such errors are reduced when having some physical support to help anchor the hands.
Gesture-Based Inputs
By the time that propulsion breakthroughs become viable, it is likely that gesture-based
commands will have evolved past the current systems' problems of misinterpreting
wayward motions and will have become an effective way to replace the mouse for
cursor control. In addition, it is expected that more options will be available through
gestures than through existing mouse buttons (right click, left click, and scrolling). 44
When used in combination with a voice-command system, it is expected to be an
effective tool for the more complex and varied instruction sets, such as navigation. For
example, the notion of being able to point to a locati on on an expansive virtual map
and say, "go there," seems an ideal implementation.
Furthermore, the use of gesture-based inputs in analyzing new data seems appropriate,
provided that the lessons from adaptive displays are heeded. Although fascinating,
gesture-based commands are dependent on how well the information that they are
manipulating is organized. Therefore, these inputs might be prone to the same keyhole
errors and mode errors of adaptive displays.
Prior lessons regarding quick emergency commands should also be heeded, specifically
where all critical commands have dedicated physical controls. Gesture-based
commands can be redund ant, but again, the physical control should be the dominant
source of critical inputs . Consider the event of buffeting, where the position of an
27
UNCLASSIFIED/fFOA. OFFICIO ls. Plili ONls.¥
UNCLASSIFIED/ ,'FOR OFFI@IAI:: WSE ONl::Y
extended arm is likely to waver. This would induce significant errors in the gesture
system.
Voice Commands
Voice commands are promising for hands-free and parallel task initiation. 45 By the time
that propulsion breakthroughs become viable, it is likely that voice-command
technology will have solved the problem of voice recognition (including when stressed)
and the problem of accommodating the myriad of ways to ask for the same thing. That
having been considered, voice commands are projected to be an excellent
augmentation to the set of other cockpit controls, particularly with the more complex
and varied instruction sets, such as navigating within gesture-based systems.
Based on lessons from human-to-human communication, however, it is advised to have
the pilot's commands repeated back to them as a form of confirmation.
Brain-Machine Interface
Although research is currently in the initial stages, 46 th is study of far-future cockpits
assumes that this technology is fully matured, such that the pilots can issue commands
with their thoughts. A limiting constraint here is that only non-invasive techniques are
used (avoiding the need to modify the pilots).
Regardless of the sophistication of the technology, a weak link in these systems is the
human mind itself; that is, thoughts can wander. Much more study is required to
determine the implications of distractions, loss of concentration, fright, levels of mental
discipline, and many others.
CONTEMPORARY AIRCRAFT COCKPITS
For comparative reference, some features of contemporary aircraft cockpits are
examined next. Key displays and controls are becoming standardized, although the
placement still varies across manufacturers and models. 47 Regardless of differences,
the functions are representative of similar functions to consider for breakthrough-era
cockpits.
The layout of the Airbus A380 Flight Deck, shown in Figure 10, has major flight
functions located in specific areas. There is a combination of fixed and adaptable
displays. The following items of interest are identified:
• Primary flight display.
• Navigation display.
• Flight mode control.
• Vehicle status indicators.
• Joystick, throttles, and keypads.
28
UNCLASSIFIED/fFOA. OFFICIO ls. Plili ONls.¥
UNCLASSIFIED/ ,'FOR OFFI@IAI:: WSE ONl::Y
Flight Mode Con
Figure 10. Flight Deck of Contemporary Aircraft. As one example, the Airbus A380 Flight deck contains
displays and controls that are ind icative of displays and controls that will be needed in breakthrough-era craft.
Image source : <http ://www .flickr.com/photos/83823904@N00/641S6219/> (September 2007)
Primary Flight Display
The primary flight display (PFD) provides information about the vehicle's orientation
(pitch, roll, and compass heading), motion (speed and rate of climb), and altitude. It is
centrally located in front of the co-pilot's seat, and a smaller version is available to the
right of the pilot's navigation display. Figure 11 shows a close-up of a PFD that also
shows its heritage from the mechanical instruments of older aircraft that have now
been merged into a single computer-controlled instrument.
This instrument is vital to the safe operation of an airplane. It displays orientation
(pitch, roll, compass heading), motion (forward airspeed, rate of climb), and position
relative to a critical axis (altitude). This particular graphic was selected because it also
shows the lineage to the individual mechanical displays of prior aircraft; artificial
horizon, airspeed, compass heading, altimeter, and rate of climb. Per many of the
recommendations from human factors research, a blend of graphical and alphanumeric
elements are now used, and t he central orientation graphic, t he "artificial horizon," is a
direct physical analogy to the physical world.
29
UNCLASSIFIED/fFOA. OFFICIO ls. Plili ONls.¥
UNCLASSIFIED/ ,'FOR OFFI@IAL WSE QptLY
Figure 11. Contemporary Primary Flight Display.
Source: < http:/ / www.freshgasflow .com/physics/avia tion_and_anesthesia/ aviation_comparison .html>
An analogous display will be required for the breakthrough-era craft, but with
modifications to accommodate the full six degrees of freedom and the additional flight
regimes of orbit and deep space. For example, the artificial horizon and altimeter have
mean ing near the surface of a gravitating body, but it is not clear how effective such
references will be in flight regimes of orbit or in deep-space flight.
These orientation cues as well as compass headings are Earth dependent. Far from
Earth, the value of maintaining these cues is unknown, and substitute cues have not
been identified . Other orientation standards wi ll have to be developed for
breakthrough-era craft that will still be consistent with this aircraft convention when
operating near the surface of a gravitating body.
Navigation Display
The next most significant display is for navigation. Near Earth, this takes the form of a
map that can be augmented to show terra in and weather. Due to its importance, it has
a prominent place on the flight deck. Numerous related controls and displays are
avai lable for allowing the entry of destinations and waypoints into the system to
augment this one display screen .
Breakthrough-era craft will require additiona l navigation cues; these may include those
that will direct pilots into orbits and those for navigating in deep space.
30
UNCLASSIFIED/fFOA: OFFICIO la Plili Oralla¥
UNCLASSIFIED/ ,'FOR OFFI@IAI:: WSE ONl::Y
Flight-Mode Control
In contemporary aircraft, the flight-mode control panel is often located prominently in
the glare shield . It contains displays and controls for the autopilot and for setting
headings, speeds, and other operational parameters. In breakthrough-era craft, there
will likely be no need for a glare shield, since all images of the exterior will be projected
indirectly; thus, the intensity of the light can be limited. Nonetheless, having a
prominent location for the flight -mode display is critical.
Vehicle Status Indicators
The status of critical operating pa rameters of the vehicle, such as its fuel level and
eng ine temperature, is essentia l. Note the prominence of those displays in the center of
the flight deck. However, other than knowing that similar displays and controls will be
required for breakthrough -era cockpits, it is too early to speculate on their details.
Joystick, Throttles, and Keypads
Some sort of physical controls are required to fly the aircraft. On contemporary aircraft,
these include the joystick (side-mounted), rudder pedals, and throttle controls. Fine
tun ing controls that manage features such as trim settings and flight heading can be
located on separate panels. The details of these controls are dependent on the methods
of flight. For a breakthrough craft, it is reasonable to speculate that six-degree-of
freedom controls will be accommodated by whatever method is most natural for pilots.
Figure 12. Space Cockpit Visions Circa 1959 . Taken directly from Seifert's 1959 book, Space Technology, this
is an artist's rendering of a "space travel control statio n." It is offered here to convey the provisional nature of far
future speculations, including the speculatio ns offered in t his report.
31
UNCLASSIFIED/fFOA. OFFICIO ls. Plili ONls.¥
UNCLASSIFIED/ ,'FOR OFFI@IAL WSE QptLY
Chapter 3: Provisional Cockpit for Breakthrough Flight
Applying the strategy of using the most demanding situations to guide designs, the
provisional cockpit presented here assumes a single pilot. Without any crew amongst
whom to disburse the workload, such a cockpit must be more efficient and effective.
The "design for stress" approach is also applied, which drives the design to have actual
physical displays and controls that are concentrated in a "tunnel vision" zone. The
elements on these physical panels are predictably fixed, owing to lessons of human
factors.
Newer technology such as virtual reality displays with augmented reality and gesture
based inputs are also included, along with voice and thought commands. Based on
lessons from adaptive display errors, and considering the limits of human
concentration, limits are imposed on the use of voice and thought commands .
The overall configuration is shown in Figure 13 and consists of a modest set of physical
panels surrounding a seated pilot, along with a large virtual display surrounding the
entire area. The most critical displays and controls are condensed into the forwardmost
panels.
FLIGHT MODES
The most fundamental flight mode is the full manual mode. Each subsequent flight
mode offers increasing levels of automated assistance, up to and including a fully
autonomous control mode that can operate even when the pilot is incapacitated. A
provisional set of flight modes (whose buttons and indicators are presented across the
central flight mode panel from left to right) include the following:
• Full manual.
• Manual w/safe assist.
• Interactive assist.
• Fully autonomous (keyed to emergency responses).
Full Manual
As the name suggests, this is where the pilot has full control over the motion of the
vehicle through joysticks, switches, gestures, voice, and thought. This is the most
difficult flight mode for the pilot, and accordingly provides the best situation from which
to design the guidance displays and to set the requirements for the various control
inputs.
In subsequent studies, 48 this would be the flight mode to specify when addressing the
challenges of guiding the pilot for entry into orbits and navigating in difficult situations.
32
UNCLASSIFIED/fFOA: OFFICIO la Plili Oralla¥
UNCLASSIFIED/ ,'FOR OFFI@IAL WSE QptLY
·-----
Figure 13. Provisional Breakthrough-Era Cockpit. The spherical zone around the cockpit center represents the
virtual surround display onto which images of the environment outside the vehicle are displayed. Keeping with
lessons of prior human interfaces, a min imal set of physical displays are also provided, with the most important
ones located deliberately in the "tunnel vision" zone in front of the pilot. [Graphic: A. Szames with backgrou
Fuente: archivo UAP oficial del gobierno de EE.UU. (dominio público) · war.gov/ufo ↗ · ver en el archivo de Nodriza