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Safety
Introduction
The worldwide commercial aviation major accident rate has been nearly
constant and quite low for two decades. Despite the low rate, increasing
traffic over the years has meant an increase in the actual number of
accidents. With the worldwide demand for air travel expected to more
than double by 2017, such a traffic volume could lead to 50 major
accidents per year. Clearly, that many accidents would badly erode the
public's confidence in the aviation system. These facts led to the
setting of national aviation safety goals by President Clinton in
February 1997.
The current general aviation accident rate (excluding corporate
aircraft) is many times greater than commercial aviation's. Decreasing
the GA accident rate is critically important to the National GA roadmap
goal of "doorstep-to-destination travel at four times highway speeds."
Safety considerations must be removed as a barrier to the GA market
revitalization now getting underway.
The FAA has defined the near term national goal to be: "By 2007, reduce
the U.S. aviation fatal accident rate per aircraft departure, as
measured by a 3-year moving average, by 80 percent from the 3-year
average for 1994-1996."
The NASA plan for meeting the national safety goal is to develop
technologies that reduce aircraft accident, fatality, and injury rates.
Specifically, the program will address accidents caused by hazardous
weather, controlled flight into terrain, human-error, and mechanical or
software functionality. The program will look to improve information
technologies, from data gathering to information delivery. The focus of
each element is to develop prevention, intervention, or mitigation
strategies.
The FAA plan for reaching the national safety goal is to focus on four
strategic areas, including selected research and development activities.
First, implement a regulatory process that is timely, responsive, and
consistently applied. Second, develop partnerships with the aviation
community to share data and information supporting safe, secure
aviation. Third, develop new approaches to inspection and surveillance.
Fourth, based on root-cause analyses, prevent accidents before they
happen through appropriate, targeted, and systematic interventions.
Aviation Weather Information (AWIN)
The past 20 years have seen significant research advances in aviation
weather hazards, including icing, turbulence, lightning, and wind shear.
Yet, weather continues to be identified as a contributing factor in
nearly a third of all accidents. Flight crews, air traffic controllers,
and airline operation centers need better collection, processing,
distribution, and presentation of timely and accurate weather
information.
The goal of NASA's Aviation Weather Information (AWIN) program is to
provide timely, accurate, easily understood weather information to
National air space users so they can take safe, efficient, and cost
effective actions. In the early 1990's, a NASA-industry team developed
and evaluated a Cockpit Weather Information (CWIN) system. CWIN combined
and presented weather information from multiple data link sources.
Piloted simulation studies and flight tests demonstrated that cockpit
graphical weather information enhances efficiency, safety, and
situation awareness.
Cockpit weather information display
NASA and industry teams are expanding the CWIN concept in cooperation
with the FAA to create an entire air and ground data link
infrastructure. AWIN solutions will allow transport and general aviation
aircraft, air traffic control, airline operation centers, and weather
providers to share graphical weather data and to make collaborative
decisions.
NASA POCs:
Ron Colantonio
216-433-6370
Renato.O.Colantonio@grc.nasa.gov
Paul Stough
757-864-3860
H.P.Stough@larc.nasa.gov
Web Sites:
http://AWIN.larc.nasa.gov
http://www.hq.nasa.gov/office/aero/oastthp/programs/avsaf/avsafpro.htm
Wind Shear Sensing Systems: An FAA/NASA Success Story
A meteorological phenomenon known as a "microburst" can occur in or near
thunderstorms and is often responsible for a particularly nasty form of
wind shear. This wind shear can cause large and small aircraft alike to
loose control and crash with little or no warning. Between 1964 and
1985, over 25 U.S. airline accidents, 625 fatalities, and 200 injuries
were caused by wind shear. In addition to new training and
weather-avoidance procedures, the FAA in 1988 mandated that airlines
install wind shear warning devices, or detection avoidance systems, by
the end of 1993.
Reactive systems are not capable of giving advanced notice of wind
shear. They alert the flight crew after wind shear is encountered.
Following this warning, the crew can then take corrective action to
avoid contact with the ground.
NASA scientists at Langley Research Center worked with several avionics
and airline industry representatives to develop predictive systems for
wind shear avoidance systems. The systems that resulted from this work
provide 10 to 60 seconds of warning when wind shear conditions exist in
the flight path„adequate time for the flight crew to maneuver around or
safely through the hazardous wind shear condition. A system has been
commercialized by a U.S. equipment manufacturer and was first
incorporated by Continental Airlines.
NASA POC:
Lucy Crittenden
757-864-1776
L.H.Crittenden@larc.nasa.gov
Aircraft Icing Research
The Aircraft Icing Research project supports the NASA Aero-Space
Technology Enterprise's "Global Civil Aviation" pillar. The research
efforts address the aviation safety goal of reducing accident rates due
to icing hazards and the affordability goal of reducing time and cost of
design and certification of icing systems. These goals are accomplished
by developing methods and tools as a foundation to provide information
and technology solutions for the aviation system. Major technology
elements of the Aircraft Icing project include icing weather
information, icing simulation, icing effects, icing operations, and
icing education and training.
Shown in the accompanying picture is an icing effects phenomenon known
as tailplane icing, wherein ice accreted on the horizontal stabilizer
causes it to stall and results in uncontrolled pitch, a situation that
has lead to fatal general aviation aircraft accidents.
The joint FAA Technical Center and NASA Glenn program has identified the
aerodynamic and handling characteristics of an aircraft in an
ice-contaminated tailplane stall. Pilot training materials have been
developed based on the results of this investigation. The training
video, which is targeted to pilots of general aviation and commuter
aircraft, describes the tailplane icing phenomenon, defines the expected
handling characteristics of an aircraft in a tailplane stall, and
explains what recovery maneuvers pilots can perform.
NASA POC:
Thomas B. Irwin
216-433-5369
Thomas.B.Irvine@grc.nasa.gov
FAA POC:
Charles O. Masters
609-485-4135
charlie.masters@faa.gov
Turbulence Detection and Mitigation
Atmospheric turbulence is the leading cause of in-flight injuries to
passengers and flight crews. FAA statistics show that 98 percent of
those injuries happen because people aren't wearing seat belts. An alert
of impending rough air would give pilots time to warn passengers and
flight attendants to buckle up and take steps to reduce turbulence
effects. Turbulence is not only hazardous, it also costs the airlines
time, in the form of re-routing and late arrivals, and money, an
estimated $100 million a year.
Turbulence is often associated with visible storm systems. Aircraft can
use available radar systems to detect and avoid that form of rough air.
But currently there are no effective systems to warn flight crews of
clear air turbulence that generally occurs at cruising altitudes.
Detecting nonvisible turbulence with a laser light beam will
provide
pilots valuable seconds for warning crew and passengers and
taking safety precautions.
A NASA-industry team has already flight tested a sophisticated laser
device which was able to sense previously undetectable clear air
turbulence. The Airborne Coherent Lidar for Advanced In-flight
Measurement (ACLAIM) project came out of technology developed for a high
speed civil transport.
Work is also underway to better understand and predict clear air
turbulence and develop reliable and effective detection and mitigation
concepts. This goal requires:
- Development of highly reliable detection technology to sense
dangerous turbulence with sufficient warning to institute defensive
maneuvers
- Improved resolution of forecasts to provide 6-hour prediction of
turbulence that would reduce the frequency of encounters by 80 percent
- Development of rough air encounters technology that would reduce or
alleviate dangerous turbulence effects by 40 percent
NASA POCs:
Rod Bogue
661-258-3193
bogue@x500.dfrc.nasa.gov
Ron Colantonio
216-433- 6370
R.O.Colantonio@grc.nasa.gov
Frank Jones
757-864-5271
F.P.Jones@larc.nasa.gov
Synthetic Vision
Synthetic vision system displays allow the presentation of scenes with
sufficient information and realism to be equivalent to a bright, clear,
sunny day„regardless of outside weather conditions. The display can
depict scenes of terrain, attitude, and traffic. Symbolic information
can be overlaid on the scenes to enhance situation awareness and
tactical guidance.
Poor visibility is implicated in most controlled-flight into terrain
(CFIT), runway-incursion, and general aviation loss-of-control
accidents. The better pilot vision provided by enhanced, or synthetic,
vision display systems offer the potential to eliminate
visibility-induced errors for these types of accidents and mitigate
accidents of other types as well.
Synthetic vision scene with symbolic information overlaid to
enhance situtational awareness.
Synthetic vision systems are not yet in service, and significant
research effort is required before implementation is possible. Most
significant are the cost, certification, and liability issues associated
with a fully functional synthetic vision system and its underlying
database. The development of a compelling business case that could serve
as an economic incentive, over and above the safety benefits of a
synthetic vision system, is also a significant hurdle. NASA will work
with the FAA, industry, and other government agencies in a research
program to overcome these hurdles in order to aid commercial integration
of synthetic vision displays into the worldwide aviation system
environment.
NASA POC:
Russell Parrish
757-864-6649
r.v.parrish@larc.nasa.gov
Fatigue Countermeasures Program
Responding to a congressional request, NASA Ames Research Center created
a program to examine whether "there is a safety problem of uncertain
magnitude, due to transmeridian flying and a potential problem due to
fatigue in association with various factors found in air transport
operations." The NASA Ames Fatigue/Jet Lag Program was created to
collect systematic, scientific information on fatigue, sleep, circadian
rhythms, and performance in flight operations.
747 pilots participating in the Cockpit Rest Field Study,
performed in collaboration with the FAA.
Three program goals were established and continue to guide research
efforts:
- To determine the extent of fatigue, sleep loss and circadian
disruption in flight operations
- To determine the impact of these factors on flight crew performance
- To develop and evaluate countermeasures to mitigate the adverse
effects of these factors and maximize flight crew performance and
alertness
Studies have been conducted with the support and collaboration of the
FAA in a variety of aviation field environments, controlled laboratory
settings, as well as in a full-mission flight simulator. In the early
nineties, the name of the program was changed to the Fatigue
Countermeasures Program to provide a greater emphasis on the development
and evaluation of countermeasures.
Recent studies include:
- An evaluation of the onboard bunk sleep of flight crews in augmented
long-haul flights
- A 747-400 simulator study of the effectiveness of in-flight activity
breaks for flight crews during long overnight flights
- A test of the feasibility of a video-based system for unobtrusively
tracking and monitoring pilot fatigue
NASA POC:
Dr. David Neri
650-604-0658
dneri@mail.arc.nasa.gov
Web Site:
http://olias.arc.nasa.gov/zteam/
Aviation Performance Measuring System (APMS)
The APMS research team is developing the next generation of tools for
the U.S. Flight Operations Quality Assurance (FOQA) program. In
collaboration with Alaska Airlines and United Airlines, the APMS Project
Team has successfully developed and demonstrated an integrated suite of
tools for routinely converting very large masses of flight-recorded data
into information. This provides timely and accurate "situational
awareness" essential for assurance of quality and safe performance of
the aviation system. It is anticipated that APMS will play a central
role in attaining the programmatic goals of Aviation Safety Program and
the FAA's Global Analysis and Information Network (GAIN) program. Under
NASA's Aviation Safety Program, APMS will eventually be extended to
service the needs of engineering, maintenance, and training in the
airlines, and to commuter, cargo, and corporate air carriers.
An integrated suite of tools for routinely converting very large
masses of flight-recorded data into information.
NASA POC:
Dr. Irving C. Statler
650-604-6655
istatler@mail.arc.nasa.gov
The National Aging Aircraft Research Program
As a result of concerns relating to the increasing age of the air
carrier fleet, the FAA is conducting research to ensure the continued
airworthiness of high-time, high-cycle aircraft through its National
Aging Aircraft Research Program.
Structural integrity research is primarily focused on the effects of
simultaneous cracks at multiple structural details on the integrity of
large and small transport aircraft structures. Methodologies for
predicting damage tolerance and fatigue lives are being developed.
Capturing landing impact data, through a video acquisition
system
for large and small transport aircraft.
Inspection systems research is focused new methods and techniques for
detecting cracks, corrosion, and disbonding. Much of the basic research
is done at the Center for Aviation Systems Research (CASR), a consortia
of Iowa State, Northwestern, Wayne State, and Tuskegee Universities. The
FAA Aging Aircraft Nondestructive Validation Center (AANC) at Sandia
National Laboratory conducts validation and final development of
inspection procedures.
Aircraft engine research focuses on developing a methodology for
predicting crack growth in engine static components and will use that
methodology to derive maintenance and inspection management program for
commercial pressurized engine cases. It also is developing improvements
in titanium billet inspection and in-service inspections of engine
components. This research is being done by the Engine Titanium
Consortium, which is made up of Iowa State University, General Electric,
Pratt & Whitney, and AlliedSignal Engines.
The Airborne Data Monitoring Systems research program has developed a
video landing data acquisition system that collects data on landing
impact conditions for both large and small transport aircraft. A series
of surveys are underway at commercial airports. In addition, flight load
data are being collected for large and small transport aircraft.
Through the Maintenance and Repair Research program improved maintenance
and repair technologies are being identified and maintenance and repair
practices from effective programs are being incorporated into
appropriate user documentation.
Rotorcraft Structural Integrity research in this area is focused on two
activities. The first will provide input for an Advisory Circular on
health and usage monitoring system certification criteria for
rotorcraft. The second will address the use of damage tolerance methods
to establish inspection intervals for existing and new rotorcraft
designs.
FAA POC:
Thomas Flournoy
609-485-5327
thomas.flournoy@faa.gov
FAA's Aircraft Catastrophic Failure Prevention Program
The FAA's Aircraft Catastrophic Failure Prevention Program is working to
improve aircraft system safety by developing technologies and methods
that will assess the risk and prevent defects, failures, and
malfunctions of aircraft, aircraft components, and aircraft systems
which could result in catastrophic failure of aircraft. By using
enhanced computational capabilities and vulnerability analysis
techniques, the program will provide technologies and certification
criteria to increase the survivability of transport aircraft with
extensive failures, malfunctions, or damage.
A model for catastrophic engine failure.
Currently, FAA engineers are working with industry to develop a
calibrated design system that will be used to minimize hazardous effects
of turbine engine (including auxiliary power unit) rotor failures on
transport aircraft. In partnership with industry and the Aerospace
Industries Association Transport Committee on Propulsion System
Malfunction Plus Inappropriate Crew Response, the FAA also is developing
improved training methods and an engine failure warning system that will
be used to decrease the incidence of inappropriate crew response to
propulsion related problems.
FAA POCs:
Robert Pursel
609-485-6343
Robert_Pursel@admin.tc.faa.gov
William Emmerling
609-485-4009
William_Emmerling@admin.tc.faa.gov
Self-Nulling Probe
The self-nulling probe is a unique eddy current probe developed to
detect small cracks in thin skin fuselage. A specialize instrument
detects small cracks under rivet heads in lap joints by rotating the
probe around a rivet being inspected. This instrument was extensively
tested at the FAA Aging Aircraft Nondestructive Inspection Validation
Center, where it successfully detected cracks 32 mils long in the outer
layer of a lap joint and 125 mils long in the third layer of a tear
strap. It has also been field tested at Boeing Long Beach, where it was
used to inspect DC9 and DC10 crown sections. Forester Instruments, Inc.,
is currently commercializing this instrument which uses the self-nulling
probe. Current NASA efforts involve extending the capabilities of the
technology to enable the detection of subsurface cracks in thick wing
skins.
New sensor is capable of locating cracks 70 percent smaller than
cracks detected using current devices.
NASA POC:
Dr. William P. Winfree
757-864-4963
w.p.winfree@larc.nasa.gov
FAA's Aircraft Crashworthiness Research Program
The FAA's crashworthiness research program has two specific technical
goals: the elimination of structural design, manufacturing, or
maintenance faults that could lead to an accident and the improvement of
crash design features to provide better protection for passengers and
crew in an accident.
Testing for better passenger and crew protection.
This research program is composed of four task areas: aircraft dynamic
testing, aircraft water impact and flotation, transport fuel
containment, and aircraft cabin interior safety. For testing, a vertical
drop tower and its supporting facility are located at the William J.
Hughes Technical Center at the Atlantic City International Airport, NJ
(see next article). For analytical modeling, the FAA has developed
computer programs that predict crash damage to aircraft, crash gravity
loads sustained by the aircraft structure, gravity loads transmitted to
seats, and the resultant forces experienced by seated occupants. For
example, the FAA developed the KRASH computer code to analyze airframe
crash effects. This code has been modified and improved to accommodate
light aircraft, rotorcraft, and transport aircraft. Complementing the
KRASH code for airframe loads and damage are two computer programs for
seated passengers. One is a Seat Occupant Model for Light Aircraft
(SOMLA) and the other is for Seat Occupant Model for Transport Aircraft
(SOMTA). Use of these computer programs with the KRASH code provides a
basis for estimating the effects on seat occupants from crash loads
transmitted from the airframe to the seats. The FAA is also
participating in the development of an analytical tool in partnership
with the United Kingdom Ministry of Defense and the Air Accident
Investigation Board (AAIB) at the Cranfield Impact Centre.
FAA POC:
Gary Frings
609-485-5781
gary.frings@faa.gov
Dynamic Vertical Drop Test Facility
The FAA's Dynamic Vertical Drop Test Facility is used to obtain the
empirical data needed to set crashworthiness standards and to obtain
other crashworthiness data to assess the impact response characteristics
of airframe structures, seats, overhead stowage bins, auxiliary fuel
tanks, and the potential for occupant impact injury.
The drop test facility is comprised of two 50-foot vertical steel towers
connected at the top by a horizontal platform. An electrically powered
winch, mounted on the platform, is used to raise or lower the test
article and is controlled from the base of one of the tower legs. The
current lifting capacity of the winch is 13,600 pounds. The platform
rests on I-beams and is supported by 12 independent load cells. The load
cells are used to measure the fuselage impact on the platform.
Data collected from tests, such as the most recent drop test of a
commuter Shorts 330 aircraft, will be used to improve standards for
seats, overhead stowage bins, and auxiliary fuel tanks.
FAA POC:
Gary Frings
609-485-5781
gary.frings@faa.gov
FAA's Full-Scale Curved-Panel Test System
Completed in 1998, the Full-Scale Curved-Panel Test System is capable of
testing full-scale curved-panel specimens under conditions
representative of those seen by an aircraft in actual operation. The
data obtained from the tests will be used to validate analytical models
being developed by the FAA. All testing is monitored using state-
of-the-art video equipment for continuous observation.
General aviation seat material information can help transports
with seat dilemmas.
Developed under contract with the Boeing Company, the test system
applies pressure and longitudinal, hoop, and shear loads to test
specimens. A graphical interface allows the operator to control the
loads, speed, and type of test. Data from strain, load, and pressure
transducers, are displayed in real time and can be stored for later
analysis. A remote video system will be integrated with the test rig to
track and record crack propagation and to measure crack openings during
the tests. The video system has a very wide zoom range and can pan from
the entire panel to a crack tip.
FAA POC:
Dr. John Bakuckas
609-485-4784
john.bakuckas@faa.gov
NASA's Aviation Safety Program
In the Aviation Safety Program, Accident Mitigation (AM) is identified
as one of five critical areas. Accident mitigation includes the systems
approach to crashworthiness and fire prevention. The systems approach to
crashworthiness plans have three major elements that focus on human
occupant survivability. The first element is prediction methodologies.
The goal of the prediction methodologies work is to establish a FAA
accepted/industry standard commercial dynamic analysis code to perform
analyses of the crash energy management system of an aircraft. The
second element is structures, materials, interiors, seats and
restraints. The goals for this element are to define design criteria,
develop energy management concepts, provide test data for analysis
validation, and proof of concept testing. The third element is crash
resistant fuel systems. The goal here is to prevent/reduce the amount of
fuel spillage after a crash and allow more time for occupant egress. The
approach is to define existing fuel systems, identify deficiencies,
transfer technology developed by the DoD to the civil aircraft
community, and develop new concepts.
NASA has been involved with crashworthiness for more than 20 years.
NASA, the DoD and General Aviation communities have worked together on
many crashworthiness issues such as energy absorbing seats, energy
absorbing structures and airbag technology. One of the most successful
cooperative activities is the Advanced General Aviation Transport
Experiment (AGATE) program. In AGATE, a general aviation consortium
exists to advance technologies in several areas. Energy absorbing seat
technology is one of the areas. The AGATE crashworthiness group has
developed a methodology that can expedite certification,
recertification, and retrofit of aircraft seats and is applicable to
transport category aircraft.
NASA POC:
Lisa Jones
757-864-4148
l.e.jones@larc.nasa.gov
Aircraft Fire Safety
In its commitment to fire safety, the FAA operates the most extensive
civil aircraft fire test facilities in the world. The centerpiece of
this testing capability is a full-scale fire test facility, which is
used to study fire scenarios under realistic conditions. Five other
facilities are also devoted to small-scale fire tests of interior
materials, fire tests on aircraft components and large-scale specimens,
chemical analysis related to the toxicity of combustion products,
extinguishment of simulated engine fires, and examining the effects of
altitude and air speed on fire behavior.
Through its fire safety program research and testing efforts, the FAA
has set a number of industry fire standards, such as seat cushion
fire-blocking layers and low heat and smoke release interior panels
(sidewalls, stowage bins, ceilings, and partitions). The FAA's work also
has lead to heat-resistant evacuation slides, floor lighting, flight
recorder fire endurance, Halon 1211 hand-held extinguishers, airline
blanket ignition resistance, and guidelines for approving Halon
replacement agents.
Engineers currently are working on numerous projects focusing on
materials fire safety, fire management, and systems. For example, the
agency is evaluating the fire performance of current thermal acoustical
insulation as well as the need for tougher fire test standards. Work
will soon commence to develop test standards for approval of new cargo
fire detectors that are being developed to reduce the high incidence of
false alarms. In addition, cargo water spray tests are under way to
examine the effectiveness of this promising technology against various
cargo fire threats, including exploding aerosol cans. Future research
will address fire safety criteria in large passenger capacity,
double-decked aircraft, which aircraft manufacturers are now designing.
FAA POC:
Constantine (Gus) Sarkos
609-485-5620
constantine.sarkos@faa.gov
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