Enhancing Pilot Ability to Perform Continuous Descent Approach with Descriptive Waypoints

CALIFORNIA STATE UNIVERSITY, NORTHRIDGE
Enhancing Pilot Ability to Perform Continuous Descent Approach with
Descriptive Waypoints
A thesis submitted in partial fulfillment of the requirements
For the degree of Master of Arts in Psychology,
Human Factors and Applied Psychology
By
Michael C. LaMarr
December, 2010

ii
The thesis of Michael LaMarr is approved by:
Dr. Nhut Ho Date
Barry Berson, M.A. Date
Dr. Tyler Blake, Chair Date
California State University, Northridge

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Acknowledgments
Dr. Nhut Ho
Thanks for your advice, guidance, support, and critique throughout the research and
thesis writing process. Your guidance on meaningful research gave me the drive to keep
on task and kept me going on to do the best work that I could produce.
Dr. Tyler Blake
I am grateful for your guidance throughout my education in the Human Factors Master’s
program. You taught me that it is important to start from the outside and to work my way
in and to keep up with technology and new practices in the Human Factors world.
Barry Berson
Thank you for your support on my thesis writing and helping me whenever I had any
trouble. Your classes taught me the tools and how to use them to be a successful Human
Factors professional. You also taught me how to connect with other Human Factors
professionals and I have made many connections because of you.
Dr. Walter Johnson, Vern Battiste
Thanks for all the meetings we had about the design of my thesis. I had to work extra
hard just to make sure everything was up to standard. Also thanks for the opportunities
of working with you guys on your research and for allowing me the opportunity to work
with pilots and air traffic controllers.
Joe Biviano
Thanks for all your time in helping me design my flight scenarios and making them as
realistic as possible. I couldn’t have done this study without your help.

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Table of Contents
Signature Page................................................................................................................................................ ii
Acknowledgments......................................................................................................................................... iii
List of Figures ................................................................................................................................................vi
ABSTRACT................................................................................................................................................. vii
Background .....................................................................................................................................................1
Continuous Descent Approach Benefits .....................................................................................................1
Continuous Descent Approach Challenges.................................................................................................3
Descriptive Waypoints to aid in CDA Arrivals ..........................................................................................7
Display of Descriptive Waypoints ..............................................................................................................9
Objective .......................................................................................................................................................14
Hypotheses ....................................................................................................................................................15
Method ..........................................................................................................................................................17
Participants................................................................................................................................................17
Design.......................................................................................................................................................17
Material.....................................................................................................................................................19
Facilities....................................................................................................................................................21
Procedure ..................................................................................................................................................22
Results...........................................................................................................................................................25
Time Variation..........................................................................................................................................25
Power Usage .............................................................................................................................................26
Attitude and IAS Deviation.......................................................................................................................27
Perceived Workload..................................................................................................................................33
Preference Number of DW .......................................................................................................................34
Discussion .....................................................................................................................................................36
Hypothesis One.........................................................................................................................................36
Time Variation..........................................................................................................................................36
Power Usage .............................................................................................................................................36
Attitude Deviation.....................................................................................................................................37
IAS Deviation ...........................................................................................................................................38
Hypothesis Two ........................................................................................................................................39
Time Variation..........................................................................................................................................40
Power Usage .............................................................................................................................................40
Attitude and IAS Deviation.......................................................................................................................40
Hypothesis Three ......................................................................................................................................41
Time Variation, Power Usage, Altitude and IAS Deviation .....................................................................41
Hypothesis Four........................................................................................................................................41
Perceived Workload..................................................................................................................................41
Hypothesis Five ........................................................................................................................................42
Preferred DW Amount..............................................................................................................................42

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Subjective Data and Feedback.......................................................................................................................43
Flight Chart Feedback...............................................................................................................................43
Vertical View of CSD Feedback...............................................................................................................43
DW Feedback ...........................................................................................................................................43
Pilot Strategies ..........................................................................................................................................45
Feedback on CDA scenarios.....................................................................................................................46
Limitations ....................................................................................................................................................47
Future Research.............................................................................................................................................48
Conclusion.....................................................................................................................................................49
References.....................................................................................................................................................51
Appendix A: Example Flight Chart..............................................................................................................54
Appendix B: Training Manual......................................................................................................................55
Appendix C: Orientation PowerPoint...........................................................................................................63
Appendix D: Training Checklist ..................................................................................................................67
Appendix E: Practice Run Checklist ............................................................................................................68
Appendix F: Pilot Responsibilities...............................................................................................................69
Appendix G: Debrief/ Questionnaire............................................................................................................70

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List of Figures
Figure 1: Conventional Approach ..................................................................................................................2
Figure 2: Conventional Approach and Continuous Descent Approach..........................................................3
Figure 3: Flap Cues Recommended by Koeslag (1999) in Primary Flight Display .......................................5
Figure 4: Energy Management System used by NASA Langley Research Center ........................................6
Figure 5: DW Cues with Flap, Altitude and Indicated Air Speed References (Ho 2006) ..............................8
Figure 6: 2D Navigation Display ...................................................................................................................9
Figure 7: Flight Chart Final Approach .........................................................................................................10
Figure 8: Three Descriptive Waypoints........................................................................................................11
Figure 9: Coplanar Navigation View (Prevot, 1998)....................................................................................12
Figure 10: 3D Cockpit Situation Display .....................................................................................................13
Figure 11: Experimental Design Matrix.......................................................................................................18
Figure 12: Wind Speed.................................................................................................................................18
Figure 13: MACS on left and Cockpit Situation Display on right ...............................................................19
Figure 14: One Descriptive Waypoint Condition.........................................................................................20
Figure 15: Three Descriptive Waypoints Condition.....................................................................................20
Figure 16: Five Descriptive Waypoints Condition.......................................................................................21
Figure 17: Pilot Station Setup ......................................................................................................................22
Figure 18: Mean Time Deviation Main effect on Wind ...............................................................................26
Figure 19: Average Power Main effect on DW............................................................................................27
Figure 20: Average Altitude Deviation Main effects on DW.......................................................................28
Figure 21: Average Altitude Standard Deviation on DW ............................................................................29
Figure 22: Average Altitude Deviation Main effects on DW 1....................................................................30
Figure 26: Workload Main effect on DW ....................................................................................................34
Figure 27: Preferred number of DW for each Wind Condition....................................................................35

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ABSTRACT
Enhancing Pilot Ability to Perform Continuous Descent Approach with
Descriptive Waypoints
By
Michael LaMarr
Master of Arts in Psychology, Human Factors and Applied Psychology
Objective: Conduct an experimental study to determine the effectiveness of using
Descriptive Waypoints (DWs) (a target/checkpoint in space along the flight path that
gives the pilot altitude and indicated airspeed) to improve flight performance during
Continuous Descent Approach (CDA) procedures, and provide recommendations on DW
design and integration into existing CDA procedures.
Background: Aircraft noise is a burden on people living around airports and is an
impediment to the growth of air transportation. CDA is an approach that reduces noise
impact on the ground by keeping the aircraft at a higher altitude longer than standard
approaches and by keeping engines idle or near idle. However, CDA implementation
requires controllers to add large separation buffers between aircraft because aircraft of
different sizes and weights descend at different rates, consequently creating uncertainty in
separation between aircraft. A possible solution to allow aircraft to descend more
consistently is to use DWs to provide pilots targets and feedback along the CDA path.
Method: Twelve Instrument rated commercial pilots participated in a 3 by 3 Within
Subject Factorial Design. Participants flew three different wind conditions using one,
three, or five number of DWs. Dependent variables included: deviation from target DW
altitude and Indicated Airspeed (IAS), deviation from Required Time of Arrival (RTA),
average power usage, perceived workload, and pilot acceptance of DWs. Objective and
subjective data were collected to evaluate the effectiveness of the number of DWs.
Results: As the number of DW increased pilots mean altitude deviations decreased by
726 feet and standard deviations by 332 feet with a slight increase in perceived workload
and one percent in power usage. Wind had a significant effect on RTA with mean times
being within eleven seconds of each other. Pilots would prefer to have two DWs targets
in each wind condition, and felt comfortable using DW to fly CDA.
Conclusion and Application: The results showed that DWs can be used as an effective
cuing system to enhance pilot ability to perform CDA, and that they are a potential choice
for near to midterm implementation in improving the effectiveness of CDA approach and
landing procedures.

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Background
Continuous Descent Approach Benefits
Noise and emissions produced by aircraft when landing are a burden on people
living around airports and is an impediment to the growth of air transportation. The
produced noise limits how many aircraft can land at night and the ability to expand more
runways or build new airports in populated areas. Another problem with air
transportation expansion is the cost of fuel, which is about 27% of the operation cost to
airlines (Lowther, Clarke, & Ren, 2007). Lowther (2007) also mentions that with air
traffic growth expected to increase 150% by 2025, corresponding increase in noise,
emissions, and fuel will be a problem for the air transportation system.
Currently, aircraft descend and land at different speeds based on their size and
weight, making it difficult to predict their future trajectory. Air Traffic Controllers
(ATC) compensate for dissimilar aircraft performance by creating an approach pattern in
which all aircraft fly level flight segments at the same speeds as they enter the terminal
area (Reynolds, H., Reynolds, T. & R. Hansman, 2005). This practice makes it less
challenging for the ATC to separate aircraft; however, it creates a significant noise
impact on the local community. The noise is most profound in areas where the aircraft
have to fly at low altitudes near the runway because of the existing navigation
constraints. Specifically, aircraft land by using an instrument landing system (ILS) (see
Figure 1) glide slope to intercept the glide path at the correct descent angle to the runway.
The ILS provides the pilot with lateral and vertical guidance to maintain the correct
approach orientation for landing. This is accomplished by leveling off at an altitude that
allows the aircraft to intercept the glide slope from below. If the aircraft flies above the

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glide slope it may intercept a false glide slope and come into the airport at an incorrect
landing angle.
Figure 1: Conventional Approach
To operate within the navigation constraints of the ILS and reduce noise impact,
noise abatement approach procedures have been developed and implemented. One such
procedure is Continuous Descent Approach (CDA). CDA also offers other benefits such
as fuel savings and lower emissions impact by using an idle or near idle power by
decelerating the aircraft at a higher altitude longer than the standard landing procedure
without reverting to level flights (see Figure 2). A CDA study flight demonstration was
conducted in Louisville, Kentucky with Boeing 767-300 aircraft equipped with the
Pegasus flight management system (FMS) (Clarke, Ho, .et al 2006). It was shown that
CDA can reduce noise by 3.5 to 6.5 dBA (3 dBA is noticeable to the ear) and fuel
consumption by 400 to 500 pounds.
10,000
Feet
4,000 feet
ILS Glide Slope
Airport

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Figure 2: Conventional Approach and Continuous Descent Approach
Continuous Descent Approach Challenges
Implementation of CDA is not practical in moderate to high traffic because it
requires a larger separation buffer between aircraft than the standard landing procedure.
Predicting where the aircraft will be is cognitively taxing on the controller and pilots
because deceleration is non-linear and humans have a difficult time judging non-linear
deceleration when speeds are constantly changing (Reynolds, H. 2006). To implement
CDA, ATC have to know when aircraft are at the right distance from the airport to
initiate the clearance to start the CDA approach procedure. If the air traffic controller
tells the pilot to initiate CDA too early, then the aircraft will arrive before the runway and
will have to level out before landing. Leveling out early requires power increase, which
in turn creates more noise and defeats the purpose of the procedure. If the air traffic
controller tells the pilot to initiate the procedure too late, then the pilot will end up
making a fast landing or have to fly around and make another landing attempt (which
produces more noise and uses more fuel, which also defeats the purpose of the CDA).
4,000
feet
ILS Glide
Slope
Runway
Continuous
Descent
Approach
Conventional
Approach
10,000
Feet

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Other challenges to the implementation of CDA procedures remain the difficulty
that pilots have managing the deceleration of aircraft in the presence of uncertainties in
pilot response time, vertical navigation (VNAV) (controls vertical automation of aircraft
according to flight profile programmed in the flight management system (FMS))
performance, and wind conditions (Clarke, Ho, et al., 2006). Koeslag, M. F., (1999) also
identified other problems with current CDAs. The first problem is that vertical flight
profile is not fixed and depends on the FMS installed, and if there is no vertical capability
it depends on the skill and training of the pilot. The second problem is that wind can
cause the aircraft to deviate from the FMS-predicted flight trajectory. This unpredicted
interference can cause the flight trajectory to differ from the true flight trajectory, causing
the pilot to make adjustments such as adding thrust. Wind deviations can cause a +/- 2
minute deviation from the FMS trajectory. One of Koeslag’s proposed solutions was to
fix the vertical profile of CDA to improve arrival time predictability. Another issue
being addressed was to update the flap profile of the aircraft when there were speed
deviations. This profile is displayed in the primary flight display. Koeslag developed an
algorithm to address problems with the FMS and tested it in a simulator, but concluded
that many real world tests will need to be conducted to deal with various aircraft sizes
and weights in multiple wind conditions. One recommendation that Koeslag made to
assist pilots performing CDA is to add flap guidance in the primary flight display (PFD)
(see Figure 3).

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Figure 3: Flap Cues Recommended by Koeslag (1999) in Primary Flight Display
Other research efforts aiming to make CDA more predictable focus on equipping
the flight management system with 4D guidance (x, y, z, and time). Moore (2009)
proposed 4D information with a required time of arrival (RTA) to help ATC establish a
strategic time scale of CDA traffic flow. The algorithms designed in this research are
aimed to minimize time, fuel, and emissions produced. One problem noted is that
automation can cause the VNAV to make occasional thrust changes that can cause extra
noise and fuel usage. Other research on RTA during CDA operation proposed to provide
pilots with an energy management cueing system (see Figure 4) in the navigation display
to minimize fuel, noise, and emissions by providing pilots with optimal vertical path with
energy events and energy error cues for managing throttle and drag (Williams, 2008).

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Figure 4: Energy Management System used by NASA Langley Research Center
Another study, conducted at Louisville International airport, found that near term
CDA implementation is possible by conducting flight tests (Clarke, Ho, Ren, Elmer,
Tong, & Wat, 2004). The authors noticed in the flight tests that the FMS and pilot delay
had some undesired effects on noise produced by the aircraft. Pilot delay in initiating the
flaps could have undesired effects on VNAV that could cause the aircraft to deviate from

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the altitude programed on the FMS. Another problem with the VNAV is that when
descending, VNAV’s logic gives the altitude constraint higher priority than the speed
constraint, and with factors such as tail wind, the aircraft would not always meet the
speed targets. It is important to meet both the speed and altitude constraints on the flight
path for fuel and time efficiency, and for traffic separation.
Descriptive Waypoints to aid in CDA Arrivals
These studies have been beneficial to CDA research, but are aiming for mid to
long term implementation; until better VNAV logics and FMS designs can compensate
for pilot delay, altitude and speed constraints, and wind uncertainties, the pilot has to
control the vertical profile manually. If pilots have information to help them stay on the
flight path, managing their aircraft’s speed, and arrive at the airport at a predictable time,
CDA would be more feasible for daily use. One way to aid pilots to execute CDA is to
give them feedback information. Without the help of a cuing system, pilots find it
difficult to manage the aircraft energy to meet a target speed at a specific altitude in the
presence of uncertainty. According to Ho (2006), there are two reasons for uncertainty
during CDA. One reason is the pilot’s inability to estimate future position of aircraft
because the deceleration profile is non-linear. The second reason is that the pilot’s
projection may be incorrect because of wind uncertainty. In Ho’s study, gates (for
consistency purpose, gates will be called Descriptive Waypoints (DW) in this thesis)
(altitude and speed target along the flight path) varying in number (zero, one, two, and
three) were proposed to use with a flap schedule. Each of these conditions also had wind
uncertainty and no wind uncertainty. For the two DW condition, the DWs were located
at 5000 and 3000 feet from the runway, and the three DW condition had DWs at 5000,

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4140, and 3000 feet. Pilots were given DWs on a cue card (see Figure 5). In the three
DW condition, pilots were able to achieve the target speed at a higher rate than the other
conditions.
Figure 5: DW Cues with Flap, Altitude and Indicated Air Speed References (Ho
2006)
CDA is being considered at further distances for fuel savings and emissions
reduction. Coppenbarger researched oceanic tailored arrivals (OTP) which starts CDA at
37,000 to 40,000 feet altitude. OTP uses CDA in constrained airspace conditions by
integrating advanced air and ground 4D automation through digital datalink with the
aircraft FMS. Results showed that the fuel savings with Boeing 777 is between 200 and
3000 lb per flight (Coppenbarger, Mead, and Sweet 2006).
After reviewing these studies, the idea of Descriptive Waypoints (altitude and
speed target along flight path) (DW) was formed. The name DW was given because
dynamic waypoints (target altitude and speed waypoints that can be created in real time,

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with relying on existing waypoint database) focus on providing updated waypoint
information and DW is a description of a waypoint that could include a time target, flap
requirement, gear deployment, target altitude, and speed. For this study, only altitude and
Indicated Air Speed (IAS) was provided in the DW. Flap information was displayed in
the PFD.
Display of Descriptive Waypoints
With the description of DW defined, it is important to examine how to display the
information to the pilot. Currently, pilots use a navigation system to keep track of where
they are going. Information such as other aircraft, weather, and terrain can be displayed.
The navigation system (see Figure 6) is a useful way of informing the pilot of the general
surroundings, but is currently limited to a 2D perspective.
Figure 6: 2D Navigation Display

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Pilots also use arrival charts when they are on their final approach, with the
vertical information (altitude) displayed as text as in the 2D navigation display, as well.
See Appendix A for an example full flight chart (Global Aviation Navigation, Inc.,
2009). Figure 7 represents the vertical profile the pilot needs to take to intercept the glide
slope to land.
Figure 7: Flight Chart Final Approach
Thomas and Wickens (2006) found that it is easier to make specific and accurate
judgments based on absolute spatial information displayed in 2D with 3D information.
This is because 3D displays tend to make the x, y, and z axis ambiguous whereas 2D
information gives precise x, and y information, but will need the 3D information in text.
So, is it better to display information in 3D or 2D to the pilot during CDA? There is a
problem that occurs while using 3D views. Without other depth cues available, the
location of objects become ambiguous (Cowen, John, Oonk, & Smallman, 2001). Even

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with this problem 3D views do have their advantages. For example, shape understanding
is beneficial in 3D, whereas 2D is more accurate for precision tasks (Symmes & Pella,
2005). There is no clear answer for which display is better for DW, but for the current
study it makes sense to display the information to pilots in 2D because they are only
controlling their vertical descent during CDA, without traffic separation and terrain
avoidance.
A near term solution is to display DW information in a vertical flight chart (see
Figure 8). Flight charts typically display the final approach right before the glide slope at
roughly around 3,000 to 10,000 feet altitude. In a study by Ho (2006), it was shown that
providing vertical information and DW at 7,000 feet altitude improved pilot ability to
perform CDA. The current study is taking the vertical information provided to the pilot
back to 23,000 feet altitude at 70 miles from the airport. This is motivated by the fact
that CDA procedures are being proposed to start at a very far distance from the airport,
such as the top of descent location, which is typically at 37,000 to 40,000 ft.
Figure 8: Three Descriptive Waypoints

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A possible solution for near to midterm is to use a coplanar view (horizontal and
vertical profiles) of the navigation with DW information. The vertical display would
benefit pilots, enabling them to monitor the vertical profile when VNAV is turned off and
the pilot is manually flying the vertical profile (Prevot, 1998) (see Figure 9).
Figure 9: Coplanar Navigation View (Prevot, 1998)
Another possible long term solution that can help the pilot perform CDA more
efficiently is to use DW displayed in Cockpit Situation Display (CSD) to provide 3D
visualization of the flight plan (see Figure 10). CSD is a navigation aid that pilots can
use to gain information of surrounding air traffic, alert them of possible conflicts, provide
spacing tools, etc. CSD takes care of 3D ambiguities by allowing the pilot to rotate the
screen 360 degrees and switch to 2D at any moment.

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Figure 10: 3D Cockpit Situation Display

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Objective
The objective of this study was to conduct an experimental study to determine the
effectiveness of using Descriptive Waypoints in CDA procedures and provide
recommendations on DW design and integration into existing CDA procedures. This
study expands on past research of providing pilots with DW information by
implementing the DW at a farther distance and at a higher altitude than in previous
studies. Thus, this current study is more of a strategic approach to perform CDA by
starting at a cruise altitude compared to the Ho (2006) study of using DW near final
descent. Also being studied is short to midterm implementation, whereas other studies
aimed for a mid to long term implementation, with a focus on FMS algorithm
development.

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Hypotheses
Hypothesis one is that, as the number of Descriptive Waypoints increases,
required time of arrival deviation, average power of aircraft, and altitude and IAS
deviation will decrease. This is the result found in Ho (2005), and is also supported by
Reynolds (2005) work on adding structure, or standardization, to the procedure, to reduce
uncertainty and thereby improve the pilot’s ability to predict future locations along a
flight path.
The second hypothesis is that required time of arrival, average power, and altitude
deviation will be less for the nominal wind speed condition in comparison to the slow and
fast wind speed conditions. Koeslag (1999) stated that wind can cause aircraft to deviate
from flight path and cause a +/- 2 minute deviation in time. Also, Ho (2006) states that
pilot’s projection may be incorrect because of wind uncertainty.
The third hypothesis is that as number of Descriptive Waypoints increase,
required time of arrival, average aircraft power, and altitude deviation will be the same
across the different wind conditions. One DW gives pilots freedom of flight which
would create variation among the different wind conditions. With five DWs, there is a
strong structure for the pilot that should make the variation practically the same for all
wind conditions.
The forth hypothesis is as the number of Descriptive Waypoints increase,
perceived workload will increase. One DW gives pilots less constraints to meet, and
should not drive up pilot workload. Three DWs generate more structure and slightly

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more workload, while five DWs should provide even more structure and constraints for
the pilot to meet, and the perceived difficulty can go up.
Hypothesis five is that pilots will prefer five Descriptive Waypoints in all wind
conditions. Pilots in the Ho (2006) study preferred to have three DWs, but this was for a
short distance from the runway. Over a longer distance such as the one studied in this
thesis, it was predicted that five DWs would be preferred by pilots.

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Method
Participants
Participants included twelve instrument-rated, commercial pilots (11 male, 1
female) between the ages of 24 and 67 (Mean 37.64 years old) with years of flying
between 2 and 37 years (Mean 18.75 years) and with 590 to 23,000 (Mean 7660) hours
flight time. Two pilots with CDA experience, and one with CDA simulation experience,
participated in this experiment.
Design
A 3 wind (Fast, Normal, and Slow) x 3 DW (One, Three, and Five) within-subject
factorial design was used (see Figure 11). In the Fast wind condition, the wind speed
started at 52.8 knots (60% increase over the normal wind condition), the Normal wind
condition had a starting wind speed of 33 knots, and the Slow wind condition had a
starting speed of 19.8 knots (40% decrease in normal wind) (see Figure 12). These wind
conditions were based on historical data at Louisville International Airport, and the wind
conditions were chosen to produce noticeable differences. The One DW condition
provided the pilot with an end target to achieve, the Three DW condition provided the
pilot with three targets, and the Five DW condition provided the pilot with five targets.
The number of DWs was designed to vary the amount of feedback provided to the pilots.
Dependent variables included: altitude and IAS deviation, computed as the
absolute deviation from target DW altitude and IAS. Altitude deviations and IAS
deviations are metrics used to evaluate how adding feedback helps pilots maintain CDA.
RTA is computed by determining the absolute time in seconds from target time (fast wind
target time 720s, normal wind target time 750s, and slow wind target time is 770s).

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Varying RTA for different wind conditions gives the pilot different arrival time targets
and provides data to evaluate the effects of using DWs on improving the separation
buffer, which is an indication of the airport throughput. Power usage was computed as
the average power the aircraft uses during the CDA. Perceived workload, pilot
acceptance of DW, pilot strategies and other subjective data were collected in a
questionnaire (rating scales and open ended questions) (see appendix G) to evaluate the
effectiveness of DW and obtain feedback on pilot acceptance and the integration of DW
into existing CDA procedures.
1 DW x Slow Wind 3 DW x Slow Wind 5 DW x Slow Wind
1 DW x Normal Wind 3 DW x Normal Wind 5 DW x Normal Wind
1 DW x Fast Wind 3 DW x Fast Wind 5 DW x Fast Wind
Figure 11: Experimental Design Matrix
Figure 12: Wind Speed
0
10
20
30
40
50
60
0 5000 10000 15000 20000 25000
Altitude
Fast Wind
Normal Wind
Slow Wind
WindSpeed

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Material
Stimuli were displayed on two 19” monitors, one running Multi Aircraft Control
Station (MACS) software and the other monitor, Cockpit Situation Display (CSD)
software (see Figure 13). MACS is a dynamic interface that allows the pilot to fly and
interact with the aircraft’s systems, such as IAS, vertical speed, flap settings, and altitude.
The CDA landing procedure flight plan was shown on a 2D fixed vertical view of CSD.
DWs will be displayed on a flight chart as one, three, and five DWs. The vertical profile
was developed by NASA in a study (Prevot, T., Callantiner, T. Kopardekar, P., Smith,
N., Battiste, V., 2004). Modifications were made by creating aircraft start and end points,
removing all traffic, and by adding DW locations with energy consideration, noise,
deceleration, speed/altitude targets, and power usage.
Figure 13: MACS on left and Cockpit Situation Display on right
In the one DW condition, pilots see their flight plan on their flight chart (see
Figure 14). The only information pilots received is a target to intercept five miles from
the airport. Figure 14 through 16 present an example of the one, three and five DW
conditions. The vertical profile is the same in all conditions.

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Figure 14: One Descriptive Waypoint Condition
Figure 15: Three Descriptive Waypoints Condition

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Figure 16: Five Descriptive Waypoints Condition
A training manual (see Appendix B) was developed to train pilots how to use the
MACS and CSD interfaces that were used for the experiment. A PowerPoint presentation
(see appendix C) was developed to introduce the pilot to the task and goals for the
experiment. Two checklists were developed to assess pilot learning. The first checklist
(see appendix D) checked pilot understanding of the training manual. The second
checklist (see appendix E) made sure the pilot could perform the tasks that were required
for the experiment during a practice CDA simulation.
Facilities
The study was conducted in the Systems Engineering Research Laboratory
(SERL) (see Figure 17). Pilots were in a room with a one-way mirror and sat at a desk
with two computer monitors, a flight chart and used a mouse to interact with the
monitors.

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Figure 17: Pilot Station Setup
Procedure
Pilots were contacted by the experimenter by phone. CDA and DW were
described to the pilot. Date and time of the experiment were set and a training manual
(see Appendix B) was emailed to the pilots. On the day of the study, the experimenter
administered the participant bill of rights, consent form, and reviewed the training manual
with the pilot. After that, the pilots were shown a short PowerPoint presentation (see
appendix C). This presentation informed the pilot that they are flying for a company
called Silent Deliveries. This presentation also discussed CDA and pilot goals. The
company’s three goals, starting with highest prioritized goal of achieving all of the
Descriptive Waypoints at the specified altitude (range of +/- 300 feet) and IAS targets
were described to the participants. Another restriction to IAS is that the pilot must keep
speed under 250 IAS below 10,000 altitude. The second goal was to achieve the last DW
at RTA within 30 seconds. The third goal was to keep aircraft power below 10%, but
keep it as close to 0% as possible. Also, from 10,000 feet to the last Descriptive
Waypoint, power should be monitored more closely.
Pilots were told to be alert and not leave speed brakes on when not decelerating,
to avoid power increase. Pilots were also told that LNAV will be engaged and that

23
horizontal navigation is not required. VNAV will be turned off: vertical navigation by
pilot will be required, flaps must be used as indicated on PFD, and landing gear must be
down by 5.5 nm from SDF.
After the presentation, the experimenter went over the training manual. This
manual explained the controls for the MACS software and information that is displayed
on the CSD. After that, the pilots were trained to use the software and were given the
objectives of the study. The experimenter loaded the MACs on the left 19” monitor, and
CSD on the right 19” monitor.
The experimenter then gave an oral checklist to the pilot to check the pilots’
understanding of the training manual (see appendix D). The training checklist asked the
pilots to identify the vertical speed indicator and buttons, IAS indicator and buttons, PFD
power indicator, flap location on PFD, flap settings, speed brakes, and landing gear on
the MACs display. If a pilot had trouble with any of this, the experimenter took a note of
it and assisted the pilot to find the correct location on the MACs display. Also, the
checklist indicated that the wind speed and direction are located on the navigational
display on the MACS screen.
After the checklist, the experimenter loaded up a CDA practice run. The practice
run was different than the experimental run. Experimenter also had the pilot fly CDA,
and went over another checklist (see appendix E) to make sure the pilot could perform
the tasks that were required for the experiment. This checklist asked the pilot to change
the vertical speed and IAS, use flaps, speed brakes, and landing gear to make sure the
pilots could make the changes on their own. Also, the experimenter showed the pilot
how the speed brakes affect the power of the aircraft and asked the pilot to intercept the

24
Descriptive Waypoint Alt<10 (a waypoint shown in the CSD) at +/- 300 feet and within
+/-5 IAS deviations. The pilot was given an RTA of 5 minutes 30 seconds from Alt<10
to 5nm to SDF. After the pilot had completed all practice tasks, the pilot received a paper
with instructions on pilot responsibilities for the experiment (see appendix F). After that
the experiment began.
The experimenter watched the experiment in the next room through a one-way
mirror and on camera. At the end of each experimental trial, the experimenter entered the
room to load the next scenario and give the pilot a five-minute break. After the break, the
next experiment simulation began. The experiment was broken up into nine
counterbalanced trials at about 12-13 minutes each. When the experiment was over, a
short questionnaire/debrief (see appendix G) that included likert scales, lists, and open
questions were given to pilot followed by a short interview. The pilot was then
compensated $50.

25
Results
Time, average power, altitude and IAS deviations were collected from MACS
output and put into excel for each participant for nine conditions. Data was organized by
dependent variable, and a 3x3 (Wind x DW) analysis of variance (ANOVA) on SPSS 17
was run for each of the dependent variables.
Time Variation
There was a non-significant main effect of DW on time, F(1.698, 18.678)= 2.096,
p=0.156, and a significant main effect of Wind on time ,F(1.873, 20.605)=7.172,
p<0.005, etap
2
=0.879. High wind (mean=13.87 sd=18.59) resulted in significant different
time compared to Slow wind (mean=17.28 sd=13.33) and Normal wind (mean=25.03
sd=17.64). Time difference between High wind and Slow wind was 3.41 seconds, Slow
wind to Normal wind 7.75 seconds and from Normal wind to Fast wind was 11.16
seconds. There was not a significant interaction effect between DW and Wind on time, F
(2.884, 31.721)=1.67, p=0.912. Figure 18 shows the mean time deviations on Wind.

26
Figure 18: Mean Time Deviation Main effect on Wind
Power Usage
There was a significant main effect of DW on average power, F(1.928, 21.203)=
3.731, p<0.042, etap
2
=0.609 and no significant main effect of Wind on average power
F(1.299, 14.288)=0.350, p=0.620. One DW (mean=7.25 sd=2.31) resulted in significant
difference of average power, compared to the three DW condition (mean=7.62 sd=2.39)
and five DW condition (mean=8.35 sd=3.45). One DW difference between three DW was
.37 average power, between three DW and five DW was .73 average power, and between
five DW and one DW was 1.1 average power. There was not a significant interaction
effect between DW and Wind on average power, F (2.495, 27.442)=0.826, p=0.472.
Figure 19 shows the mean power for different DW conditions.
0
5
10
15
20
25
30
Slow
Wind
Normal
Wind
High
Wind
RTADeviationInSeconds

27
Figure 19: Average Power Main effect on DW
Attitude and IAS Deviation
For ease of illustration, Figure 16 shows the vertical profile and DW along the
flight path. In these sections, location DW 1 is 18nm to Cheri, DW 2 is Cheri, DW 3 is
Alt<10, DW 4 is 10nm to SDF, and DW 5 is 5nm to SDF.
There was a significant main effect of DW on altitude deviation on DW targets 2
through 4, F(1.392, 15.308)= 26.364, p<0.000, etap
2
=1.000 and no significant main
effect of Wind on average altitude deviation on DW targets 2 through 4 F(1.861,
20.468)=0.547, p=0.586. Five DWs (mean=196.06 sd=238.90) resulted in a significant
difference in average altitude deviation compared to three DWs (mean=516.00
sd=287.68) and one DW (mean=922.32 sd=570.61). The difference between five DWs
and three DWs was 319.94 altitude deviation, between three DWs and one DW was
406.32 altitude deviation, and between five DWs and one DW was 726.26 altitude
0.00
2.00
4.00
6.00
8.00
10.00
1 DW 3 DW 5 DW
AveragePowerPercentage

28
deviation. There was not a significant interaction effect between DW and Wind on
altitude deviation of DW targets 2 through 4, F (1.875, 20.621)=0.311, p=0.709. Figure
20 shows the mean altitudes in the DW targets 1 through 5 and Figure 21 shows standard
deviations of altitudes.
Figure 20: Average Altitude Deviation Main effects on DW
0
200
400
600
800
1000
1200
1400
1600
DW
1
DW
2
DW
3
DW
4
DW
5
1 DW
3 DW
5 DW
DWCondition
AltitudeDeviationinFeet

29
Figure 21: Average Altitude Standard Deviation on DW
There was a significant main effect of DW on altitude deviation at location DW 1
(see Figure 16, DW 1 is 18nm to Cheri), F(1.820, 20.019)= 4.115, p<0.034, etap
2
=0.639
and no significant main effect of Wind on altitude deviation at location DW 1 F(1.472,
16.190)= 1.3670, p=0.276. Five DWs (mean=378.59 sd=270.60) resulted in a significant
difference in altitude deviation compared to three DWs (mean=687.58 sd=527.18) and
one DW (mean=612.18 sd=465.83). The difference between three DWs and five DWs
was 308.99 altitude deviation, between three DWs and one DW was 75.4 altitude
deviation, and between five DWs and one DW was 233.59 altitude deviation. There was
not a significant interaction effect between DW and Wind on altitude deviation at
location DW 1, F (2.666, 29.326)=0.891, p=0.447. Figure 22 shows the mean altitudes
at location DW 1.
0.00
200.00
400.00
600.00
800.00
1000.00
1200.00
1400.00
1600.00
DW
1
DW
2
DW
3
DW
4
DW
5
1 DW
3 DW
5 DW
DWCondition

30
Figure 22: Average Altitude Deviation Main effects on DW 1
(see Figure 16, DW 2 is Cheri), F(1.338, 14.718)= 17.834, p<0.000, etap
2
=0.991, and no
significant main effect of Wind on altitude deviation at location DW 2, F(1.434,
15.774)= 1.100, p=0.336. Five DWs (mean=170.04 sd=255.25) resulted in significant
one DW (mean=749.84 sd=523.80). The difference between five DWs and three DWs
was 148.87 altitude deviation, between three DWs and one DW was 430.93 altitude
deviation, and between five DWs and one DW was 579.8 altitude deviation. There was
not a significant interaction effect between DW and Wind on altitude deviation at
location DW 2, F (2.573, 28.304)=1.139, p=0.345. Figure 23 shows the mean altitudes
at location DW 2.
0.00
200.00
400.00
600.00
800.00
1000.00
1200.00
1400.00
1 DW 3 DW 5 DW
DW 1 Altitude Deviations

31
(see Figure 16, DW 3 is Alt<10), F(1.060, 11.656)=5.884, p<0.031, etap
2
=0.618 and no
significant main effect of Wind on altitude deviation at location DW 3 F(1.097, 12.072)=
0.651, p=0.449. Five DWs (mean=134.07 sd=204.37) resulted in a significant difference
in altitude deviation compared to three DWs (mean=103.22 sd=149.92) and one DW
(mean=608.41 sd=1023.40). The difference between five DWs and three DWs was 30.85
altitude deviation, three DWs and one DW was 505.19 altitude deviation, and between
five DWs and one DW was 474.34 altitude deviation. There was not a significant
interaction effect between DW and Wind on altitude deviation at location DW 3, F
(1.211, 13.319)=0.456, p=0.548. Figure 24 shows the mean altitudes at location DW 3.
0.00
200.00
400.00
600.00
800.00
1000.00
1200.00
1400.00
1 DW 3 DW 5 DW

32
(see Figure 16, DW 4 is 10nm to SDF), F(1.930, 21.226)=24.958, p<0.000, etap
2
=1.000,
and no significant main effect of Wind on altitude deviation at location DW 4, F(1.382,
15.207)= 0.139, p=0.793. Five DWs (mean=284.06 sd=474.33) resulted in a significant
one DW (mean=1408.69 sd=814.50). The difference between five DWs and three DWs
was 841.8 altitude deviation, three DWs and one DW was 282.83 altitude deviation, and
between five DWs and one DW was 1124.63 altitude deviation. There was not a
significant interaction effect between DW and Wind on altitude deviation at location DW
4, F (2.178, 23.953)=1.178, p=0.329. Figure 25 shows the mean altitudes at location
DW 4.
0.00
200.00
400.00
600.00
800.00
1000.00
1200.00
1400.00
1 DW 3 DW 5 DW

33
There was not a significant main effect at location DW 5 or the IAS conditions.
Perceived Workload
The results from a 3x1 (DW x Wind) within-subject analysis of variance
(ANOVA) revealed a significant main effect of DW on perceived workload, F(1.496,
16.451)=77, p<0.000, etap
2
=1.000. One DW (mean=2.58 sd=0.67) resulted in a
significant difference in workload compared to three DWs (mean=3.25 sd=0.75) and five
DWs (mean=4.17 sd=0.72). The difference between one DW and three DWs was 0.67
perceived workload, three DWs and one DW was 0.92 perceived workload, and between
five DWs and one DW was 1.59 perceived workload. Figure 26 shows the mean
workload for each DW condition. A likert scale was used to assess workload (see
appendix G).
0.00
200.00
400.00
600.00
800.00
1000.00
1200.00
1400.00
1 DW 3 DW 5 DW

34
Figure 26: Workload Main effect on DW
Preference Number of DW
The results from a 3x1 (DW x Wind) within-subject analysis of variance
(ANOVA) revealed a non-significant main effect of DW on Wind, F(1.877,
18.772)=2.031, p=0.161. Figure 27 shows preferred number of DWs for each wind
condition.
0
1
2
3
4
5
6
1 DW 3 DW 5 DW
DWDifficultyfromLowtoHigh
verage

35
Figure 27: Preferred number of DW for each Wind Condition
0
1
2
3
4
5
Slow
Wind
Normal
Wind
Fast
Wind
DWPreferredAverage

36
Discussion
Hypothesis One
It was predicted that as the number of Descriptive Waypoints increase, required
time of arrival deviation, average power of aircraft, and altitude and IAS deviation will
decrease.
Time Variation
There was not a significant effect on time deviation from RTA even though the
means and standard deviation are lower in the five DW condition compared to three DW
and one DW conditions. The hypothesis that more DWs would lower the RTA deviation
was not supported by the data. Pilots stated that the target RTA was not enough to keep
them at a consistent time, but they would need RTA and estimated time of arrival (ETA)
at each DW to assist them.
Power Usage
There was a significant main effect on power usage for DW. This did not support
the hypothesis that power usage would decrease as the number of DWs increased, but this
outcome makes sense. Pilots would tend to fly safe and therefore arrive at the DW target
altitude early, therefore leveling off and increasing power. Overall, in all three
conditions, there was no change in power usage; there was a small increase in power
usage of about one percent in the five DW condition. This could be a drawback to having
more DWs, but it is important to look at all performance issues before looking at this
negatively.

37
Attitude Deviation
Statistical analysis was conducted overall from location DW 2 through 4 to see
the mean altitude deviations and standard deviation. There was a main effect, but not all
targets had a Descriptive Waypoint. For example, at 18,000 feet, location DW 1 was
only a target for the five DW condition. It was important to examine the standard
deviation at each DW target as well to see the overall spread in altitude for each
condition. When looking at the standard deviation graph (see Figure 21) the five DW
condition had a noticeably lower standard deviation for each DW target than in the one
and three DW conditions. This is important because it shows that the spread of aircraft
altitude is much tighter in the five DW condition, and this helps ATC with separation of
aircraft. This is important to note because knowing the aircraft trajectory is needed for
aircraft separation and ultimately implementation of CDA in higher traffic conditions, as
mentioned by Reynolds (2005).
There was a significant main effect in the mean altitude at location DW 1. This
makes sense because the five DW condition was the only condition that had a DW target
here. The standard deviation in the five DW condition was much lower than in the one
and three DW conditions, which shows that there was a tighter grouping of the aircraft in
the five DW condition.
There was a significant main effect in the mean altitude at location DW 2. This
makes sense as well because the one DW condition does not have a DW target here. It is
interesting to see that the five DW condition has the lowest mean and standard deviation
compared to the one and three DW conditions.

38
There was a significant main effect in the mean altitude at location DW 3. We
would expect the one DW condition to have lower altitude deviation here because this
DW target is in a level flight segment of the flight profile. Three and five DW means and
standard deviations where roughly the same, which can be explained by the level flight
segment and by both conditions sharing a previous DW target.
There was a significant main effect in the mean altitude at location DW 4. The
mean and standard deviations are much lower in the five DW condition, which is good to
see because the DW target is keeping the aircraft altitude spread together. The mean and
standard deviation are a little higher than desired for the five DW condition because a
few pilots flew at a higher altitude than the DW 4 target required. This probably was the
most difficult DW target to intercept on altitude because pilots were slowing down from
240 IAS to 160 IAS, using speed brakes, and flaps while monitoring altitude.
There was not a significant main effect at the location DW 5. This makes sense
because all pilots are at the same speed of 160 IAS and an altitude of 2000 feet. Also,
pilots know that it is very important to be at the right altitude before approaching the
runway. One pilot flew this target at 5,000 feet altitude in the five DW condition so his
altitude was modified to 3,000 feet to match the third standard deviation for Figure 20.
IAS Deviation
The data did not show any significant main effects at any of the DW target
locations. This did not support the hypothesis that more DWs would result in less IAS
deviation. One reason that this outcome could have happened is that pilots would have
naturally been at the DW IAS target speed just by flying the aircraft at the altitudes the
DW targets were set at.

39
There was not a significant main effect at location DW 1, which makes sense
because all aircraft start out at 305 IAS and the first target is 305 IAS.
At location DW 2, all aircraft start out at 305 IAS and the first target is 305 IAS.
The trend indicates that one-DW aircraft start to deviate here, which suggests that pilots
will slow down earlier if they do not have a hard speed target.
At location DW 3, the target speed is now 240 IAS. Aircraft in the five DW and
three DW conditions have a hard speed target, but aircraft in the one DW condition also
have to be at 240 IAS because once the aircraft gets below 10,000 feet altitude, it is
mandatory to be at or below 240 IAS. Aircraft in the one DW have a greater IAS
deviation and the standard deviation is much higher as well, compared to three DW and
five DW conditions. The three DW mean and standard deviation would have been
slightly lower, but one pilot came in fast at 300 IAS.
At location DW 4, it was surprising that there was not a significant main effect
because one DW and three DW conditions did not have IAS targets. The aircraft where
slowing down at this point to reach a safe speed for the runway so the IAS for all three
DW conditions were similar.
Every DW condition had location DW 5 target and most pilots were already at 160
IAS by this point so it makes sense that there was not a significant main effect here and
the standard deviations were very low.
Hypothesis Two
It was predicted that RTA, average power, and altitude deviation will be less for
the nominal wind speed condition in comparison to the slow and fast wind speed
conditions.

40
Time Variation
The trend is that fast and slow wind conditions had less time deviation than the
normal condition (see Figure 18). This is not what was predicted to happen, but the
normal wind condition had the highest deviation overall. One possibility is that the target
time of 750 second for the normal wind condition was not as accurate of a target RTA to
intercept as the 720 second time for fast wind or the 770 seconds for the slow wind
condition.
Power Usage
There was not a significant effect on power usage for the wind conditions. The
average power usage did not change much from any of the wind conditions. It was
predicted that normal wind would have been easiest for pilots to intercept DW altitude,
which would have lowered power usage, but the data did not support this hypothesis.
Attitude and IAS Deviation
There was not a significant main effect for any altitude or IAS at any of the DW
targets, which was surprising because Koeslag (1999) stated that wind can cause aircraft
to deviate from flight path and cause a +/- 2 minute deviation in time IAS Deviation.
Also, Ho (2006) stated that pilot’s projection may be incorrect because of wind
uncertainty. Pilots are more used to the normal wind condition, so altitude and IAS
deviation should have been better compared to slow and fast wind conditions. The
difference in performance probably did not occur because the different wind conditions
did not create uncertainty for the pilots, but instead just became different descent profiles
to manage.

41
Hypothesis Three
As number of Descriptive Waypoints increase, required time of arrival, average
aircraft power, and altitude deviation will be the same across the different wind
conditions.
Time Variation, Power Usage, Altitude and IAS Deviation
There was not an interaction in any of the conditions. This was surprising
because Reynolds (2005) pointed out that structure creates less uncertainty. The idea that
the uncertainty of the wind conditions would affect the performance in time, power,
altitude and IAS deviations and that as number of DWs increased there should have been
reduced uncertainty and create an interaction. As stated earlier, it appears that the
different wind conditions did not create the uncertainty to affect performance, so there
was not an interaction.
Hypothesis Four
As number of Descriptive Waypoints increase, perceived workload will increase.
Perceived Workload
There was a significant effect in perceived workload. As number of DWs
increased, so did perceived workload. The main concern is if workload becomes too
high, the benefits of the DWs will start to diminish. Pilots stated that on the computer
they were only able to manipulate one control at a time and if they were in a cockpit they
would use multiple tools at a time, and that also having a co-pilot would reduce
workload.

42
Hypothesis Five
Pilots will prefer five Descriptive Waypoints in all wind conditions.
Preferred DW Amount
There was not a significant main effect on preferred number of DWs. Pilots were
given a scale to choose number of DW the pilot would prefer to have used ranging from
one through five. The expected outcome was that pilots would prefer five DWs in all
wind conditions. Instead, pilots tended to choose one DW or thee DWs. Pilots said that
the different wind speeds just required adjustments to vertical speed needed. Pilots who
selected one DW liked it for the freedom of constraints, but stated that it is unrealistic.
Pilots who selected two DWs liked the ten thousand feet DW 3 target and the 2000 feet
DW 5 target. Pilots who preferred three DWs said this condition is realistic and it is what
they are used too. Pilots also stated that they preferred one DW over three DWs because
it gave them more freedom over the control of the aircraft but would be unrealistic.

43
Subjective Data and Feedback
Flight Chart Feedback
Pilots gave a mean score of 4.42 out of 6 with a standard deviation of 1 for using
a vertical flight chart with integrated DW information. Most pilots liked the DW flight
chart, but said it was new so they gave it a lower score. Pilots also mentioned they would
like the DW information much better in combination with the Jeppesen chart, and prefer
to have the distance to next DW inserted into DW flight chart, and descent angles (based
on ground speeds).
Vertical View of CSD Feedback
Pilots gave a mean score of 3.75 out of 6 with SD of 1.22 when asked if the flight
path on the CSD helped them stay on their flight plan. Pilots would like CSD better with
a smaller aircraft on screen, bigger flight path, known vertical deviation from flight path,
green arc ("banana" for altitude confirmation), and option to zoom in and out. A pilot of a
Boeing 757 said his Cockpit setup (vertical NAV screen is next to the regular NAV
screen on the right) is similar to what was done in the study. Pilots would also like
estimated time of arrival to each Descriptive Waypoint. A pilot who flies a Boeing
aircraft said he had a display that had an energy management arrow, similar to Figure 4,
which would be very helpful for flying CDA.
DW Feedback
Pilots gave a mean score of 4.67 out of six with SD of 0.78 when asked if they
were comfortable with the DW target locations in the flight plan. Pilots liked the spacing
and how 10,000 feet altitude helped them slow down. One pilot said that it was difficult

44
for him to slow down at 10,000 feet from 240 IAS to 160 IAS until the end of the
scenario.
When asked how DWs help pilots fly CDA, the pilots responded it gives cross
checks that help determine descent rates and to know if they are on the flight path and
target; two pilots felt that it was necessary to have something tell if they are off the flight
path.
When asked how much distance should be between each DW, pilots said ranges
from no less than 5nm to 30nm. Pilots preferred 10-30nm and only less distance for
precision closer to airport.
When asked if DW helped manage vertical speed eight, pilots said yes, but
cautioned that too many DWs increase workload. Two pilots said no because it increased
workload and the pilots had to generate their own descent rates.
When asked if DW helped the pilot manage vertical speed, pilots felt that the
10,000 feet (location DW 3) and location DW 5 were only necessary for speed. One pilot
mentioned that he would like a target to let pilots know when to initiate slow down. Two
pilots mentioned they would fly quicker without restrictions.
When asked if DW helped pilots with RTA, they responded no for the most part.
Pilots in general did not pay attention to it after 10,000 feet altitude. Pilots mentioned
they would pay attention to RTA more if it was provided for each DW target.
When asked if DW helped reduce power usage of the aircraft, half the pilots said
yes, if planned correctly to intercept DW altitude. If early to altitude before DW target, it
creates level off section, which increases power usage. Pilots mentioned that with the

45
green arc tool in their NAV display, they would get to the DW altitude target without
leveling off.
Pilot Strategies
When pilots were asked what were their strategies and priorities were (power/fuel,
waypoints, RTA, etc.), ten pilots put DW targets as top priority, one pilot put power as
top priority, and one put RTA as top priority. For the second priority, ten pilots put
power and two put DW targets. For the third priority, eleven pilots put RTA, and one
pilot put power. Other goals pilots said they focused on were minimal speed brakes and
vertical speed. One pilot put a priority on groundspeed.
The pilots’ rule of thumb for managing vertical speed is a three to one ratio: for
every 1,000 feet, it takes three miles, groundspeed divided by 60 gives miles travelled per
minute (use this into distance to next DW). Pilots felt DWs were just a target to confirm
that they were on the flight plan.
The pilots’ rule of thumb for decelerating was one nm for each 10knts in level
flight, use of minimal speed brakes and flaps. One pilot said just use speed brakes and
flaps, and one pilot said educated guessing.
When asked how pilots adjusted vertical speed or deceleration when they were
coming into a DW target, pilots stated that when coming in too fast they would reduce
vertical speed, and when coming in too slow, increase vertical speed. One pilot said just
make up for it at the next target when off target.
When asked how to adjust for RTA, pilots stated fly profile and hope to make it.
Three pilots said that they would slow down and speed up after 10,000 feet altitude
(location DW 3) to adjust for RTA.

46
When asked what was the strategy for speed brakes during CDA, three pilots
stated they used brakes to slow down after 10,000 feet altitude (location DW 3). Most of
the pilots said they use brakes as little as possible and used flaps as needed.
Feedback on CDA scenarios
When asked about the realism of these scenarios, pilots felt it was realistic, but
said they would fly better in aircraft, having a copilot and with tools such as green arc.
When asked what would be the functions of the pilot flying, they stated the pilot
would fly vertical speed and IAS, make decisions for making DWs, and vocalize plan and
callouts to pilot monitoring.
For the function of pilot monitoring, they stated pilots would monitor targets, air
speed, IAS, and DWs, do all calculations for pilot flying, setting altitudes, MCP, work the
gear and flaps, crosschecking altitude inputs, and talking to ATC.
One pilot commented that workload should be lowered after 10,000 feet altitude
(location DW 3).

47
Limitations
The DWs were used with limited aircraft automation to determine the effects it
had on pilot performance. In an actual aircraft, pilots would have the option to use flight
level change (FLCH), or VNAV where they felt necessary. Also, there would be a co-
pilot to help with calling out altitude changes at each DW to ensure the pilot did not
forget or miss DW fixes. Another limitation, which also increased perceived workload,
was using the knobs of the MCP to control speed brakes, and flaps. Unlike the software,
in a real aircraft multiple knobs can be used simultaneously. Also, if pilots left speed
brakes on in a real aircraft they would feel the drag, hear a beep, and know to turn it off.
With the software, pilots had to visually see that the speed brakes were still on to turn
them off. This resulted in some pilots leaving speed brakes on longer than they intended.
Another limitation, which was a research design choice, was not allowing pilots to
manipulate the CSD. This was to limit workload and training, but pilots felt that they
would have zoomed in more to the aircraft once they passed the 10,000 feet DW 3 target.
A final limitation was that this study was a part-task simulation and that pilots would be
engaging in more tasks in an actual flight and be in an environment that they are used to.

48
Future Research
It would be interesting to see future studies use a full simulation with all
automation tools available to pilots, have a copilot or a researcher act as one, and include
DW information in a Jeppesen chart with the DW chart. Other useful research would be
to provide an updated DW chart with distance to each DW and angle of descent for each
DW; integrate DW targets into CSD or another vertical display; use DW with CSD 3D
guidance, traffic avoidance and terrain.

49
Conclusion
This study had three main goals for the pilots: RTA, managing power, and
intercepting DWs on altitude and IAS. RTA was shown to be difficult to manage for
pilots with just the DWs, but in combination with projected ETA and updated time
targets based on wind, this would help pilots predict and manage when aircraft will be at
each DW and the runway, which would help with traffic throughput to the airport. The
five DW condition used slightly more power (one percent) than the one and three DW
conditions. With automated assistance (such as the green arc), the pilots believed that
they would use less power by intercepting the DW altitude target without resorting to
level flight. An important part of this study was the pilot’s ability to intercept DW
targets. The five DW condition gave structure for the pilots, and the aircraft consistently
flew similar flight paths and were closer to their DW target altitudes, which is important
for aircraft separation, especially in higher traffic conditions. DW 3 target at 10,000 feet
altitude was seen as the most important DW by the pilots. This gave the pilot time to lose
speed and get the aircraft ready for approach to the runway. DWs will help ATC with
aircraft separation, which would ultimately make CDA more feasible in high traffic
conditions. Pilot perceived workload went up as the number of DWs increased, but this
could be reduced with a co-pilot and a more realistic simulation in which multiple knobs,
and automation are available to help with prediction of future altitude based on current
descent rates.
The results of increasing performance in the three and five DW conditions support
use and implementation of DW into CDA procedures. With the recommended changes
by pilots to the DW flight chart with distance to each DW, angle of descent, and

50
implementation of DW into vertical NAV display this would make the pilots more
comfortable with flying CDA with DWs and achieve the desired noise and fuel reduction,
meet RTA requirements, and altitude and IAS targets.

51
References
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(2004). Continuous Descent Approach: Design and Flight Test for Louisville
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Clark, J-P., Bennett, D., Elmer, K., Firth, J., Hilb, R., Ho, N., Johnson, S., Lau, S., Ren,
L., Senechal, D., Sizov, N., Slattery, R., Tong, K., Walton, J., Willgruber, A.,
Williams, D. (2006). Development, Design, and Flight Test Evaluation of a
Continuous Descent Approach Procedure for Nighttime Operation at Louisville
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Coppenbarger, R., Mead, R., Sweet, D., (2009). Field Evaluation of the Tailored Arrivals
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Appendix A: Example Flight Chart

55
Appendix B: Training Manual

63
Appendix C: Orientation PowerPoint
SILENT DELIVERIES
Continuous Descent Approach (CDA)
Overview
1

64
Company Overview
• We are a delivery company that fly 757’s at night
• To keep residents happy around airports we use CDA
(keeps noise low on ground by using low power)
• We also try to be as efficient as possible by
maintaining a time schedule by arriving at airport at
specified times
2

65
Current Problem with Conventional Approach
• Cost of fuel = 27% operation cost to
airlines
• People complain about loud aircraft noise
near airports
• Can’t expand runways
• Limited air craft throughput at
night
Implementation challenges for CDA:
• Pilots have difficulty maintaining vertical flight profile without automation
Why use Continuous Descent Approach?
• Idle engine
• Less noise is produced
• Less fuel is consumed
~220lbs
• Fewer emissions produced
10,000
Feet
4,000
feet
ILS Glide
Slope
Runway
yyyyyy
Continuous
Descent Approach
Conventional
Approach

66
Company Objectives for CDA
1. Intercept all of the Descriptive Waypoints (DW) at
the specified altitude (range of +/- 300 feet) and
specified IAS targets (range +/-5 IAS)
• A speed restriction to IAS is that the pilot must
keep under 250 IAS below 10,000 altitude
2. Intercept last DW at Required Time of Arrival
(RTA) within 30 seconds
3. Attempt to keep aircraft power below 10%, but
keep it as close to 0% as possible
• From 10,000 altitude to last waypoint power
should be monitored more closely 4

67
Appendix D: Training Checklist
Training checklist (experimenter checklist to have pilot do)
1. On MACS, please point out the following on the Mode Control Panel
(MCP):
a. Vertical Speed
b. Vertical Speed Button
c. Indicated Air Speed
d. Indicated Air Speed Knob
2. Point out the speed brakes, landing gear, and flaps
3. Where is the aircraft power level on the PFD?
4. Where would the flap indicator cues be on the PFD?
5. When does the landing gear need to be used by?
6. Point out where is wind speed and direction located on navigation display.

68
Appendix E: Practice Run Checklist
Practice Run (experimenter checklist to have pilot do)
Complete the following:
1. On Macs, please interact with the following Mode Control Panel (MCP)
tools as stated by experimenter:
a. State current Vertical Speed
b. Decrease Vertical Speed
c. Increase Vertical Speed
d. State Indicated Air Speed
e. Increase Indicated Air Speed by using IAS Knob
f. Decrease Indicated Air Speed by using IAS Knob
2. Use speed brakes
a. Mid
b. Full
c. Turn speed brakes off
3. Lower landing gear then retract it
4. State current power level of aircraft
5. How many nm is aircraft from next DW?
6. State current wind speed
7. After Cheri, instruct pilot to Alt<10 intercept DW +/- 300 feet and 5 IAS
8. At Alt<10 instruct pilot to intercept last DW in five minutes and 30 seconds
(+/- 30 second buffer)
9. When aircraft gets to appropriate speed point out the flap indicator on pfd
and instruct pilot to use flaps according to MACS PFD indicator
10.Remind the pilot of the 250 kts speed limitation if he misses it.
11.If pilot doesn’t use landing gear by 5.5 nm remind them to use it.
12.At end of practice remind pilot that the goals are on a piece of paper next
to the training manual on the table and then give a break
Notes: Pay attention for how long it takes pilots to do tasks asked by pilot

69
Appendix F: Pilot Responsibilities
Pilot Responsibilities
The three goals for CDA starting with highest priority are:
1. Achieve all of the Descriptive Waypoints (DW) at the specified altitude
(range of +/- 300 feet) and IAS targets (range +/-5 IAS)
 A restriction to IAS is that the pilot must keep speed under 250 IAS
below 10,000 altitude
2. Achieve last DW at RTA within 30 seconds.
3. Attempt to keep aircraft power below 10%, but keep it as close to 0% as
possible
 From 10,000 altitude to last Descriptive Waypoint power should be
monitored more closely
 Be careful not to leave speed brakes on when preferred speed is met
to avoid power spikes
 LNAV will be turned on so navigation is not required
 VNAV will be turned off: vertical navigation by pilot will be required
 Pilots must use flaps as required as is indicated on PFD
 Pilots must have the landing gear down by 5.5 nm from SDF

70
Appendix G: Debrief/ Questionnaire
There are two main elements examined today. These are
1. Descriptive Waypoints (DW)
2. Wind Conditions
The DW examined today was to help give extra guidance to the pilot while landing continuous descent
approach. Also it was important to not only see if the DW helped out in an optimal environment, but if
they help out during different wind conditions. For each question below, please assess your level of
comfort and explain any reservations you might have.
1. How do you feel your work load was on the one DW Scenario? (circle one)
1 2 3 4 5 6
Very Low Low Moderately Low Moderately High High Very High
2. How do you feel your work load was on the three DW Scenario? (circle one)
1 2 3 4 5 6
3. How do you feel your work load was on the five DW Scenario? (circle one)
1 2 3 4 5 6
4. How do you feel your work load was on the Slow Wind Scenario? (circle one)
1 2 3 4 5 6
5. How do you feel your work load was on the Normal Wind Scenario? (circle one)
1 2 3 4 5 6
6. How do you feel your work load was on the Fast Wind Scenario? (circle one)
1 2 3 4 5 6

71
7. Today you flew multiple scenarios varying the wind and number of DW’s. What number of DW
helped you fly the CDA the most for each wind conditions? (circle one)
a. Slow Wind 1 DW 3 DW 5 DW
b. Normal 1 DW 3 DW 5 DW
c. Fast 1 DW 3 DW 5 DW
8. How would different wind conditions affect how you fly CDA with DW?
9. How comfortable would you feel flying CDA using DW implemented into an approach flight chart
similar to the one you used today in a real life scenario?
1 2 3 4 5 6
Very Uncomfortable Somewhat Somewhat Comfortable Very
Uncomfortable Uncomfortable Comfortable Comfortable
Why?
10. What DW information would you want incorporated into an approach flight chart for CDA
approaches?

72
11. Did the vertical profile view on the CSD screen help you stay on the flight plan?
1 2 3 4 5 6
Very Uncomfortable Somewhat Somewhat Comfortable Very
Why?
12. What would you want the Navigation Display and or Vertical Display screen to show you when you
fly CDA? How would you integrate DW into these Displays?
13. Were you comfortable with the locations of the DW’s?
1 2 3 4 5 6
Very Uncomfortable Moderately Moderately Comfortable Very
Why?
14. a. How many DW would you feel would be optimal to help you fly CDA? (could be any number)
and why?
b. How does DW help you fly CDA? Why

73
c. How much distance should be between each DW? Why?
d. Did the DW help you manage your vertical speed? Why?
e. Did the DW help you mange IAS speed during CDA? Why?
f. Did the DW help with making the RTA target? Why?
g. Did the DW help you keep the power of your aircraft low? Why?

74
15 a. How many nm from airport is a good place to start CDA? Why?
b. What altitude?
16. What was your strategy and priorities (power/fuel, Descriptive Waypoints, RTA, etc.) while flying
CDA? Please give a rank list and then list your technique for flying CDA.
Strategy:
1.
2.
3.
4.
5.
Techniques
17. a. What is your rule of thumb for managing vertical speed during CDA? Did DW help with your rule
of thumb?
b. What is your rule of thumb for managing deceleration during CDA? Did DW help with your rule of
thumb?

75
c. How did you make an adjustment to your vertical speed or deceleration when you intercept DW if
you are too fast/slow? Or at the wrong altitude?
d. If you were behind or ahead of RTA how did you adjust for it?
e. What was your strategy for using speed brakes and flaps during CDA?
18. What do you think of the realism of these scenarios?

76
19. Today you flew CDA with the LNAV on and the VNAV off, what functions do you think the
Pilot Flying and Pilot Not Flying would be responsible for while flying this procedure in a real
scenario?
20. Any other feedback you have about the DW’s and flying CDA today?

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