Information on cockpit display of wind shear information is given in viewgraph form. Based on the current status of windshear sensors and candidate data dissemination systems, the near-term capabilities for windshear avoidance will most likely include: (1) Ground-based detection: TDWR (Terminal Doppler Weather Radar), LLWAS (Low-Level Windshear Alert System), Automated PIREPS; (2) Ground-Air datalinks: Air traffic control voice channels, Mode-S digital datalink, ACARS alphanumeric datalink. The possible datapaths for integration of these systems are illustrated in a diagram. In the future, airborne windshear detection systems such as lidars, passive IR detectors, or airborne Doppler radars may also become available. Possible future datalinks include satellite downlink and specialized en route weather channels

Hansman, R. John, Jr.

Wanke, Craig

English

NASA Technical Reports Server

N90-20924
COCKPIT DISPLAY OF HAZARDOUS WIND SHEAR
INFORMATION
Craig Wanke
R. John Hansman
Massachusetts Institute of Technology
Based on the current status of windshear sensors and candidate data
dissemination systems, the near-term capabilities for windshear
avoidance will most likely include:
• Ground-based detection:
TDWR (Terminal Doppler Weather Radar)
LLWAS (Low-Level Windshear Alert System)
Automated PI REPS
Ground-Air datalinks:
ATC voice channels
Mode-S digital datalink
ACARS alphanumeric datalink
The possible datapaths for integration of these systems are illustrated in
the diagram.
In the future, airborne windshear detection systems such as lidars,
passive IR detectors, or airborne Doppler radars may also become
available. Possible future datalinks include satellite downlink and
specialized en route weather channels.
f WlNDSHEAR AVOIDANCE IN THE ADVANCED ATC ENVIRONMENT _'_
_::_a _:7"'"
...._.._/ PIREPS
I Digital _ f
t I..w,.I
L___.J Ground Data L. J i r_.. I I
pRECEDING PAGE BLANK NOT FILMED
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https://ntrs.nasa.gov/search.jsp?R=19900011608 2020-03-19T22:50:33+00:00Z
Uplink of ground-measured windshear information to the flight crew
presents a number of problems. Among these are:
Hazard Assessment:
Based on ground-measured information and the current tactical
situation, what constitutes a hazardous windshear?
Information Issues:
What to send: what is 'critical'
When to send it
How to send it
How to present critical info to the flight crew
The MIT effort is using the three methods outlined to address
these issues.
• PILOT OPINION SURVEYS
Current Terminal Area Windshear Procedures
Possible Future Windshear Warning Systems
• HAZARD THRESHOLD STUDY
Definition of Windshear Hazard Thresholds Through Simulation
Studies and Flight Test Data
• PART-TASK B-767 SIMULATION
Simulation of Historical and Hypothetical Windshear Encounters
Comparison of Verbal, Alphanumeric, and Graphical Presentation
Options
Effects of Message Delivery Time on Pilot Decisions
Parallel Experiments with Graphical ATC Clearance Delivery
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18
The
The
survey has two sections: Current Procedures and Future
Windshear Warning Systems. The first part included questions
about:
Pilot impressions of the hazard posed by microbursts
Pilot confidence in windshear information obtained from ATIS,
LLWAS, and PIREPS
Pilot evaluation of the adequacy of currently available windshear
alert data and the need for better and more timely alerts
section on future procedures included questions about
Modes of information relay and presentation
When the crew should be alerted
How much head-to-tail windshear is a threat
What items of windshear information are important
Who makes the avoidance decision - pilot or controller
pILOT OPINION SURVEYS
• Obtain flight crew evaluations of current windshear warning and
avoidance systems and procedures
• Obtain flight crew feedback on future windshear warning systems
and possible display formats
• Distribution: 250 United NL flight crews
• Current Data Set: 47
51% of respondents have had a hazardous windshear encounter
D.
• Dataare being used to design part-task simulator experiments with
advanced graphic and alphanumeric display formats
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19
General results indicate that microbursts are perceived as a major
safety threat and that currently available windshear alert data are not
sufficient for safe terminal area operations. Also, there is strong
ilOt support for an improved windshear alerting system. The fairly
w windshear threshold specified by the respondents is another
indication of the belief that windshear is a major threat.
Sample comments from the last question listed:
"Only the pilot can judge the capabilities of his a/c type and his
ability to cope with reported data."
"(Controller) Must make judgment calls to reD.ort only those shears
meeting some minimum standards to avoid reporting 'everything'."
51% of the respondents have had (by their own definition) a hazardous
windshear encounter.
S pILOT SURVEYS: GENERAL RESULTS
Microbursts pose a major safety hazard to
transport category aircraft.
Currently available windshear alert data are
sufficient for safe operation.
A system to provide crews better and more
timely windshear information is necessarv.
Aaree
90.2°1o 4.9%
14.6% 43.9%
97.6% 0.0%
Perceived windshear warning threshold:
Who should have the responsibility for
judging the threat due to a particular
windshear event from the (assumed
reliable) available data?
Advisory: 10.6 kts
Warning: 15.1 kts
PILOT: 83.0%
CONTROLLER: 9.5%
2O
The data are from the question"
Listed below are four currently available sources of information about
windshear in the terminal area. Please rank them in order of
usefulness, from 1 (most useful) to 4 (least useful).
Low Level Windshear Alert System (LLWAS)
Pilot Reports (PIREPS)
Airborne Weather Radar
Visual Clues (Thunderstorms, Virga etc.)
f
Pilot Rankinas: Usefulness for Windshear Avoidance of
Pilot Reports
Visual Clues
LLWAS (Low Level Windshear Alert System)
Airborne Weather Radar
Windshear Information Sources
PIREPS V_lual CI,J_ LLWAS WHIh_ I:_dm'
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21
The data are from the question:
A windshear alert could contain the following items of information.
Please rank them in order of importance. (1 = most important, 6 =
least important)
Location Shape
Intensity Intensity Trend
Size Movement
f
_: Usefulness of Available Windshear Data
Location Size
Intensity Intensity Trend
Movement Shape
Mov_mtt '
Size'
klWn, Trend '
Shape
Wlndshear Information Iteml
ml
WA
- • - : - _ - : - _
U Std. Dev.
• Avg. Pauk
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The dataare from the question:
Assuming windshear is detected by reliable ground-based sensors, how
should this information be relayed to the flight deck? Please rank in
order of preference. (1 = most preferable, 5 - least preferable)
Voice (ATIS)
Voice (ATC)
Alphanumeric/Text uplink (similar to ACARS)
Graphical display of windshear location on EFIS display
Graphical display of windshear location on separate
graphic device
_: Mode of data relay/presentation:
Verbal (ATC)
EFIS EHSI (Moving Map) Display
Alternate Graphical Display
Alphanumeric Display
On ATIS
WindshearInformationRelay/Presentation
EFIS ATC AJtGrq)h Alpha ATIS
23
The hazard assessment part of this project is motivated by the
TDWR (Terminal Doppler Weather Radar) operational evaluations
performed by MIT Lincoln Laboratory and NCAR over the past three
years. In these experiments, TDWR proved able to detect hazardous
microbursts nearly 100% of the time with a false alarm rate of 5%.
Despite the accuracy of the radar, some dangerous incidents still
occurred. One potential problem is assessment of the hazard due to a
particular microburst in a particular situation. The hazard reported by
the detection system must relate directly to what the threatened aircraft
would experience if it does penetrate the microburst. If a large threat is
predicted, and little dynamic effect is encountered, an accurate warning
can be perceived as a 'false alarm' and damage pilot confidence in the
system.
As listed, this study will compare the factors contributing to
the windshear hazard and attempt to determine a useful ane relevant
hazard criterion.
f
WlNDSHEAR HAZARD THRESHOLD EVALUATION
1987-88 TDWR OPERATIONAL EVALUATIONS
• Proved ability of TDWR to detect hazardous windshear
• Problems in dissemination of warnings:
Delays in voice transmission
Message format problems
Pilot-perceived "false alarms"
PROBLEM:
Given perfect knowledge of the windfield, what is the most
accurate and relevant assessment of a windshear hazard in
terms that the flight crew can relate to the actual dynamic
effects on their particular aircraft?
FACTORS:
• Windshear intensity measurement
• Spatial factors: off-axis penetration, microburst asymmetry
• Aircraft characteristics, weight, configuration
24
The most critical factor in the threat evaluation is how to quantify
the microburst intensity. Three possible ways are listed. The
delta-V measurement is currently used by TDWR. F-factor, a measure
of instantaneous threat, is more applicable to in. situ and airborne sensor
systems. An integrated energy loss calculation is another possibility,
better suited to long range sensors such as TDWR.
f WINDSHEARINTENSITYMEASUREMENT _'_
DELTA-V
Maximum headwind-to-tailwind component an aircraft can be
expected to encounter over a specified distance
F-FACTOR
Wx W,
g V
Developed for in situ sensors, measures loss of "potential
altitude" due to immediate windfield
INTEGRATED ENERGY LOSS
Measures expected loss of energy over a projected flight path:
including kinetic (airspeed) and potential (altitude) energy
components
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These issues will be evaluated through parametric flight simulations
and possibly actual flight data. As listed, measured dual-Doppler
windfields will be usedwith available aircraft models to examine the
effects of various factors on the microburst hazard. Once a candidate
hazard threshold has been determined, the dual-Doppler data will be
degraded to simulate a single TDWR measurement and the hazard
criterion will be re-evaluated. Supporting data may be gained from flight
tests flown this summer by the University of North Dakota in conjunction
with the TDWR evaluation.
PLANNED APPROACH
• Literature Search: Microburst-Aircraft interaction studies
• Develop Simulation
Aircraft Dynamics: 737-100, Cessna Citation
Windshear model - assume ideal sensor using
NCAR/MITLL dual doppler radar windfields
• Perform Parametric Studies
• Evaluate and modify hazard criteria based on studies
• Evaluate flight test data from UND Citation
• Simulate effect of sensor limitations on hazard threshold
validity
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The simulation is currently under development. It will be run
on a Sun 3/80 workstation with MATRIXx simulation software to
minimize development time and allow easy automation of parametric
studies.
J DUAL-DOPPLER WINDS:
TDWR Demos
JAWS
AIRCRAFTguidanceconfigurationa/c.typ DYNAMICS:strategyJ
+
_.__ TIME SIMULATION: IH INITIAL CONDITIONS:
Sun Workstation Spatial Factors
MATRIXx simulation Phase of Flight
software
I+u.+: IAirspeed and Altitude lossesDevlation from desired flight path
R_ J
27
An ongoing focus of the MIT windshear effort is the dissemination
of ground-measured and evaluated windshear information. As
displayed, several information-related issues arise and are being
addressed with several resources, including the previously discussed
pilot opinion surveys. Current research is focused around the 767
part-task simulation.
UPLINK OF CRITICAL WlNDSHEAR INFORMATION
OBJECTIVE:
Examine transfer and presentation of vital windshear information
to flight crews, based on modern ground-based sensors and
datalink capabilities.
ISSUES: What information to transmit
When to send information
Information mode: Verbal, Alphanumeric, Graphical
RESOURCES: Pilot surveys
Analysis of past windshear encounters (7/11/88)
GA part-task simulator study
Boeing 767 part-task simulator
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On July 11, 1988 a group of very severe microbursts occurred on
the final approach path to Denver/Stapleton runway 26L. Five aircraft
were affected by the event. The TDWR evaluation was in progress, and
successfully detected the microbursts. However, four of the five aircraft
involved still attempted to land and penetrated the microbursts, in one
case passing below 100 feet AGL one mile short of the runway
threshold. The problem in this case was with dissemination of the
warnings, not with detection of the microbursts. In this case, the
effectiveness of the alert was degraded sharply by a number of factors:
• Variability of aircrew interpretation of warnings: In one case, two
aircraft were given virtually identical warnings within 30 sec of each
other and made entirely opposite decisions.
• Delay inherent in voice transmissions: The minimum delay
between detection and message transmission was about 60 sec.
• The messages were often imbedded in a routine landing clearance
message, resulting in a lack of urgency; this, combined with the high
crew workload at the outer marker, may have caused the warnings to be
missed or go unheeded.
• PIREPS are critical - once the lead aircraft reported windshear,
later aircraft initiated earlier missed approaches.
f
MICROBURST EVENT: 11 JULY 1988
• Occurred during 1988 TDWR Operational Demonstration at
Denver-Stapleton Airport: Doppler Radar was operational.
• 20 minute period of intense microburst activity on final
approach to active runway 26L: shear intensity up to 80 kts
• 5 aircraft involved
• Microburst warnings promptly and accurately produced by
TDWR system: given to final approach controller
• Despite timely warning.s, 4 of 5 aircraft penetrated microbursts
and encountered significant performance losses before
aborting the approach
• Problems:
Time delays
Message format
29
This simple experiment was designed to demonstrate the gain in
pilot situational awareness due to graphical displays. By linking a
schematic graphical display of windshear location to a general aviation
simulator, a significant improvement in pilot performance was
measured. This experiment, although simple, indicates that graphical
displays are desirable and that further investigation of graphical formats
and measurement of achievable performance gain is required.
f
PART-TASK GA SIMULATION
• GA Simulator and IBM PC display
• Microburst occurring on final approach
• Non-standard missed approach procedure required for
avoidance
Ayoidance Rate
Voice only 43%
Runway-fixed display without a/c position 62%
Runway-fixed display with a/c position 94%
• 8 Pilots: 210 to 1700 hours total time
16 Approaches per display
3O
Further information presentation options are being explored through
a Boeing 767 part-task simulation, which has just been completed. The
767 was selected because its advanced 'glass-cockpit' instruments
allow for many possible alphanumeric or graphical presentations. The
major electronic and electromechanical instruments are simulated on an
IRIS graphic workstation, and an IBM is used for simulation of the major
features of the Boeing FMC (flight management computer). Mockups of
the autopilot control panel and electronic display control panel are linked
into the system through a data acquisition unit. In addition, the crew
workload is adjusted and monitored through a simple compensatory
sidetask controlled by the IRIS mouse. The final component is a pair of
headsets for pilot and 'controller'.
BOEING 767 PART-TASK SIMULATIQN
CONCEPT:
Simulation of modern "glass-cockpit" transport aircraft with
Electronic Flight Instrumentation System (EFIS) and Flight
Management Computer (FMC), allowing a wide variety of
information presentation options.
AUTOPILOT
ControlPanels: IRIS 2400T
EFIS displaycontrols electronicdisplays
Glareshieldpanel flightdynamics
navigationlogic
sidetask
[c°ulI
IBM XT
flight management
computer
controldisplayunit
data acquisition
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This figure illustrates a typical EHSI (Electronic Horizontal Situation
Indicator) in map mode for an aircraft equipped with a flight
management computer. Information displayed includes the currently
programmed flight path, nearby navaids, intersections, and airports,
wind information, and the aircraft's current heading and groundtrack.
Weather radar returns are also overlaid on the EHSI, making it even
more desirable to place windshear'information on this display.
767 EHSI - MAP MODE
3 ",'.'i.. _,M_ISY ## 9
120
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The initial experiments as described are designed to gather
more data about modes of information presentation. The experiment is
being performed in concert with a study on the benefits of delivering
ATC routing amendments graphically. Each scenario has elements
from both experiments, which should reduce the pilot learning curve and
result in better quality data. All pilot actions, including ATC
transmissions and sidetask performance, will be recorded and
time-stamped by the simulation computers. Audio and video coverage
will also be taken.
INITIAL SIMULATIONS
Performed in concert with Graphical Amendment Delivery
experiments
9 scenarios will be flown by each subject:
Denver-Stapleton Airport
3 Initial Conditions, 3 ILS approaches
Modes:
Verbal, Alphanumeric, Graphical
Microburst Position:
Off to side of approach
On final approach
On final approach and cleared missed approach path
Alert times:
When cleared for approach
2 nm outside outer marker
At or inside outer marker
Simple compensatory sidetask for workload monitoring
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If 9 subjects are obtained, as described a total of 81
approaches will be flown. Allowing 3 modes of communication and 3
different microb.urst threat conditions, 9 points per set of parameters will
be obtained. These experiments are planned for July and August of
1989.
Possible future experiments will deal with such issues as delay
times and possible graphical format options.
f INITIAL SIMULATIONS _'_
SUBJECTS:
Active Transport Category aJccrews
Time requirement: 5 hours per subject
Minimum 9 subjects desired for initial simulations
Subjects are being contacted through ALPA, to be tested
during BOS layovers
STATUS:
Simulator 99% operational
Subjects currently being sought
Results should be available for next Tri-U Conference...
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Cockpit display of hazardous wind shear information

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