Distributed On-demand Air Transportation Using Small

25TH INTERNATIONAL CONGRESS OF THE AERONAUTICAL SCIENCES

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AbstractThe current air transportation system in theUnited States is being stressed by growingdemand and it is not prepared to meet the futureneeds of the 21st Century economy. Atransformation of the National Airspace in howit operates and is managed is necessary. Oneopportunity for helping meet the growthdemands of the 21st Century and that dependsheavily on this transformed airspace is a point-to-point, on-demand small aircrafttransportation system (SATS) using very lightjets and advanced single engine piston aircraftoperating from the many small and under-utilized airports existing throughout the UnitedStates. This paper discusses the vision forSATS, its current status, and the research anddevelopment strategy to achieve the SATSvision.

1 Introduction

1.1 Air Transportation TodayDuring the last century, the advent of trains,diesel powered ships, automobiles, and aircraftresulted in the development of an effectivetransportation system that facilitatedtremendous economic growth for the UnitedStates and the World. Today, this transportationsystem is being stressed by growing demandand it is not prepared to meet the future needs ofthe 21st Century economy. The ability of theNational Airspace System (NAS) to meet thisdemand is constrained by the limited capacityinherent in the manner in which the current

NAS and hub-and-spoke system operates.Airport delays are again looming as a criticallimiting factor to hub-and-spoke-based capacitygrowth in the foreseeable future. Airlinescheduling schemes, inclement weatherconditions, and individual air traffic serviceprovider (ATSP) workload and productivitylimits are also factors that contribute to thedelay at the airport. The nation’s primary hubairports have been approaching a gridlocksituation during primary operating hours, andbuilding more runways at these locations toabsorb the projected growth in air transportationis politically and economically very difficult.Terminal area congestion is also an increasinglyimportant issue.

The growth in air travel demand may even begreater than projected since it is estimated thatthere is an even greater latent demand for airtransportation that simply isn’t met by today’sair transportation system. There is a need forfaster, more convenient, short-range airtransportation with a broader reach. Airlinedoor-to-door speeds are not much better thanautomobile travel when layovers and all theextra time spent in the terminal are included fortrips of 200-800 miles. Hub delays areproviding the impetus for business passengers toseek transportation other than airlines,especially for trips using short-haul domesticflights. Today, in the absence of any viableservice, trips are either not taken, or groundtransportation is used despite its high time cost.For short-haul domestic flights the traveler hasoptions other than an airplane, such as the usinga car or canceling their trips and usingteleconferencing. This stifles economic growth

Distributed On-demand Air Transportation Using Small Airplanes and Smalland Underutilized Community Airports

Jerry N. Hefner and Robert E. Lindberg, Jr.National Institute of Aerospace

Hampton, VAUSA

Keywords: Air Transportation Systems, Small Aircraft, Airborne Systems

and especially hurts rural and other outlyingcommunities that continue to suffereconomically due to the lack of a viabletransportation system.

It is obvious that a transformation in the airtransportation system is necessary to meet thefuture needs of the United States and the World.The Vision 100 - Century of AviationReauthorization Act in December 2003 directedthe United States Federal Government toestablish a coordinated effort through a JointPlanning and Development Office (JPDO) tocreate the Next Generation Air TransportationSystem (NGATS). NGATS was constituted asa blue print for technology development andportfolio management activities to develop thefuture aviation system that meets the growingneeds of the United States. The JPDO wasestablished within the FAA as a multi-agencyoffice coordinating the efforts of all agencies inthe federal government with a stake in aviation.These agencies and departments include theFAA, the NASA, the Department ofTransportation, the Department of Commerce,the Department of Defense, the Department ofHomeland Security, and the White House Officeof Science and Technology Policy. NGATSprovides an opportunity to coordinate thedevelopment of the future air transportationsystem that responds to the needs of the flyingpublic.

1.2 The Vision of the Small AircraftTransportation SystemOne important aspect of NGATS could be an airtransportation system using small aircraftoperating from the many under-utilized andsmall airports existing throughout the UnitedStates. Such a small aircraft transportationsystem (SATS) could enable travel at least threetimes faster than a car and use the alreadyexisting public facilities. Travel could originatefrom a nearby community airport and concludeat another community airport that is within 30minutes of your final destination. The travelcould be scheduled when needed. This new

comfortable, quiet, and convenient airtransportation option could also operate reliablyin near all-weather conditions, provide thesafety and security of the current airline system,and offer this service to you at affordable ticketprices. This is the vision for a future SATS thatuses a new generation of comfortable, reliable,and safe small, piston-engine and very light jetaircraft operating from thousands of the smalland under utilized community airports thatcurrently exist throughout the United States.Since approximately 98 percent of the Americanpeople live within a 30-minute drive of one ofthese airports, this SATS system would have aprofound impact on the quality of life andeconomy in the United States[1].

A small aircraft transportation system, such asan on-demand, point-to-point air taxi or regionalairline, offers an economically attractivecomplement to automobiles and scheduledlegacy commercial airline service for passengersand cargo with roughly 200 to 800 miledestinations. It also represents a viabletransportation mode for citizens located in ruralsections of the country that are remote from anyavailable commercial air service and providesessential transportation for disaster relief efforts,as was demonstrated following the recenthurricanes: Katrina and Rita. The economicbenefits are five-fold:

1. A SATS service into an existing public useairport, currently without commercial airservice, could stimulate an economic boom tothe local region in terms of attracting newservice and manufacturing industries, jobscreated in derivative markets such as car rentalagencies, hotels, restaurants, etc. toaccommodate the business and leisure airtravelers, and by the tax revenue generated.Note that scheduled commercial air service intosmaller towns and communities has beenshrinking in the past decade because ofunfavorable economics.

2. There are over 3400 public use airportsalready in existence that can accommodate

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SATS-like air service for negligible additionalcosts.

3. SATS technologies, such as synthetic visionavionics, and automatic surveillanceinstrumentation, coupled with 4-6 seat very lightjet and small piston airplanes, allow an air taxiservice to provide passengers and cargo withreliable, safe, comfortable, and cost-effective airtransportation options at a profit [2,3,4]. Thus,a new industry of profitable on-demand airservice providers stimulates the nationaleconomy, as well as provides a positiveeconomic impact because of the value of thetime saved by travelers avoiding long drives tohub airports, long waits in security lines, flyingat inopportune scheduled times, and multi-legflights through interconnecting hub airports.

4. SATS technologies allow for high-volumeoperations into and out of non-towered, non-radar airports by applying a self-separationcapability, which makes no additional demandson air traffic control [5]. Sales of SATSairframe and equipment are expected to grow asa result of the emergence of on-demand air-taxiservice, further stimulating the nationaleconomy. Local communities also benefit byavoiding the cost of manned towers, and theacquisition plus maintenance costs associatedwith instrument based landing systems.

5. SATS technologies allow for non-traditionalcurved/segmented overhead approach andlandings into non-towered airports [6]. Thisresults in lower noise footprints and the abilityto avoid mountainous terrain and restricted airspace, and also reduces the amount of land thatis required to be owned, maintained, and clearedby the airport authorities.

2 Status of Vision

The initial technology foundation for the SATSvision has already been built -- through thecollaborative research and development (R&D)efforts of the Federal Government, universities,and private industry. Research conducted in the

1990’s under NASA’s Advanced GeneralAviation Transport Experiment (AGATE) andGeneral Aviation Propulsion (GAP) projectsprovided the aerodynamics, propulsion,structures, and avionics technology that havebeen applied by industry to create improvedaircraft, engines, and guidance systems.

Recently, another NASA R&D project calledSATS, funded and conducted in partnership bythe National Aeronautics and SpaceAdministration, the Federal AviationAdministration, and the National Consortiumfor Aviation Mobility, developed anddemonstrated several key technologies [5-26]that provide enhanced operating capabilitiesincluding:

(1) Increased traffic capacity for small airports;without the need for expensive radar, controltowers, or ground navigation systems,

(2) Guidance systems for safe, reliability aircraftoperation to/from small airports in low visibilityconditions,

(3) Flight control and guidance displays forsafe, easy-to-fly, single-pilot aircraft operationwith enhanced situation awareness.

The SATS project concluded in June 5-7, 2005with a highly successful public exhibition at theDanville, Virginia airport. The exhibitionincluded live flight demonstrations, technicalexhibits, and analytical presentations. Althoughthe SATS project demonstrated the initialfeasibility of the enabling technologies toachieve the desired operational capability,additional technical issues and barrier still mustbe overcome to develop a fully capable, safe,secure, efficient, and affordable airtransportation element operating effectively inthe NAS to-and-from small airports throughoutAmerica.

At the request of NASA, the National Instituteof Aerospace (NIA) was tasked to develop acomprehensive, independent assessment andguidance (developed by industry, university,

and state, without the influence of any federalgovernment agency representatives) that can beused to maximize the public benefit to bederived from future Federal R&D investmentsin aeronautics. The resulting report,“Responding to the Call: Aviation Plan forAmerican Leadership,” was published in Aprilof 2005. In September of 2005, NIA undertooka supplement effort to develop a nationalstrategy to achieve implementation of the SATSvision.

To this end, non-Federal Governmentexecutives and senior researchers andtechnologists from industry, university, stategovernment, and other aviation organizationwere invited to define the high priority goals forachieving the SATS vision and to develop anddocument technology roadmaps projecting thetechnologies, time, and investments needed tofully realize the SATS vision. The product fromthis activity was a report entitled, “Research andDevelopment for Safe, Secure, and AffordableAir Transportation for Every Community inAmerica.” and this report was published by theNational Institute of Aerospace in January 2006.The NIA report describes the strategy,objectives, and benefits of an R&D plan toachieve the SATS vision and providesrecommended technology R&D roadmaps thatoffer information on the important goals,product development milestones, and theestimated resource requirements for eachtechnology area. This current paper highlightsthe recommendations of that NIA report.

3 Required Research and DevelopmentThe strategic goals defined in January 2006 NIAReport were prioritized to reflect theirimportance in achieving the vision to providesafe, secure, and affordable air transportation forevery community in America. Therecommended technology targets were groupedin four high-priority areas:

• Service Reliability• Weather Safety• Ease of Operation• Community Compatibility

Within each target area, technologydevelopment roadmaps were defined andprioritized. The current report will summarizethe work needed in these areas.

3.1 Service ReliabilityThe number-one research priority area wasdetermined to be Service Reliability. In thisarea, there are three major goals. These include:• Integration of small aircraft into the air

traffic management system• Self-controlled airspace for small, remote

community airports• Performance based operational capability

3.1.1 Integration of Small Aircraft into theAir Traffic Management (ATM) SystemThis goal was believed to have the highestpriority and aims at the effective integration ofadvanced SATS technologies involving avionicsand airport technologies for small aircraft intothe NAS and ATM system. Objectives for thisresearch are:

• Development and validation ofprocedures/technologies to effectivelyintegrate the SATS vision into the NAS;and,

• Evaluation of the safety andeffectiveness of the proceduresdeveloped above, consistent with theNext Generation Air TransportationSystem (NGATS) integrated plan.

The SATS concept will use under-utilizedgeneral aviation airports to provide more directtransportation for the 98% of the population thatlives within 30 minutes of a general aviationairport. Consequently, the neighboring hubairports and sectors may not be as greatlyimpacted by SATS traffic growth because of theredistribution of service to/from smallercommunity airports. With greater accessibilityto community airports, it is conceivable that thepopulation demographics may shift and coalescearound these airports, further relieving theprospect of hub-and-spoke gridlock.

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Integration of SATS technologies with the AirTraffic Management system will requireresearch into airspace management, automationtools, sector loading, Air Traffic Control (ATC)procedures, ATC workload, and optimization ofthe airspace around small airports to maximizesafe and efficient operations during instrumentmeteorological conditions. This leads toresearch on using self-controlled airspace forcommunity airports.

3.1.2 Self-Controlled Airspace for Small,Remote, Community AirportsThe goal for self-controlled airspace is todevelop automation suitable for seamlesssequencing and self-controlled area flightoperations that can produce a four- to eight-foldincrease in single-pilot IMC operations at underutilized, non-towered, and non-radar coveredairports anywhere in the NAS. It is proposed toconduct research, analysis, modeling, anddevelopment to determine the optimum methodfor automation of sequencing and self-controlled area operations using VFR-like freeflight procedures during IMC.

As an extension of “free flight,” the self-controlled area (SCA) concept of operationdemonstrated the potential for increased arrivalsand departures from under utilized rural andsuburban airports outside of radar coverage andwithout towers during instrumentmeteorological conditions, and without anadditional burden to air traffic control. Althoughsignificant work was completed fordemonstrating the feasibility of high-volumeoperations (HVO) at SCA airports, new researchin this area could substantially expand thenumber and safety of single-pilot HVOoperations during IMC. The ultimate goal wouldallow VFR-like free flight operations in IMCwithin any airport terminal area. Systems,procedures, and automation (ground andcockpit) are needed to permit a seamlesstransition to and from general aviation airportairspace and the National Airspace System enroute environment.

Data link communications with ATC should bethe considered to facilitate automation functionsand backup systems. Cockpit automation inconjunction with data link communications withATC and other aircraft could provide forenhanced safety of operations and reducedworkload. Significant research issues remain inregard to certification of ground-based SCAautomation to maintain and assure trafficseparation for non-normal and emergencyoperations. Research should also considerairborne-based automation for SCA operationsusing air-to-air collaborative negotiation forseparation and sequencing that actively involveseach pilot, but allows for more flexibility thanprocedural separation.

3.1.3 Performance Based OperationalCapabilityThe goal of performance-based operationalcapability is the integration of SATS operationsinto the ATM system. Research is proposed toaddress the communication, navigation, andsurveillance aspects of this capability.

3.1.3.1 CommunicationThe Information Age has come to the NAS. TheAir Traffic Management system is on the vergeof adopting a net centric operations perspective.The NGATS Integrated plan describes netcentric as “…architectures that distributeintelligence and functions to smarter andsmaller nodes in the system…” Information isshared and intelligent functions are distributedthroughout the system. The current NAS is notnet centric because information is keptcentrally; decisions made using the SATStechnology areas would focus on getting sharedinformation to “nodes” (small aircraft andairports) and enabling intelligent processing.

Data link communications will be an enablingtechnology for the future air traffic managementsystem. The net centric operation between ATMand the aircraft are predicated on high speed,reliable data link communications. Researchissues in data links will focus on architectures,data security, data integrity, application

segregation, and bandwidth maximization. Thedata link architecture will need to be designed toprovide the necessary RequiredCommunications Performance. To maximizethe bandwidth, spectrum allocation for specificaeronautical domains such as communicationsor navigation will need to be removed. Data linkcommunications will be able to select thetechnology and spectrum domain as needed toprovide the necessary efficiency, minimallatency, and minimal cost. Similar to theInternet, the sender and receiver will not carewhich channel was used as long as theinformation is received in a timely fashion.Priority schemes will be needed for time-criticaland emergency messages.

There are two topics (among many others)running through aviation today that are taggedas “data link” discussions. One topic is “datalink” in the context of controller–pilotinteractions. The goal in this topic is to relievethe congestion on the VHF voice frequencies byencapsulating common and inefficient voicetransactions with digital data streams. Examplesare routine clearances, frequency handoffs, andacknowledgements. The technology is fairlymature in the definitions and standards, referredto as Controller-Pilot Data link Communication(CPDLC). Adoption and widespread use has notyet occurred, and is farther along in Europe thanin the U.S. due to their worsening voicecongestion problem.

The other “data link” topic is of a larger scopeand is also less mature. It is the realization thatit is not just the “voice communication” part ofthe ATM system that has data linkrequirements, but all aspects of air trafficmanagement will benefit from automation ofroutine actions which in turn creates the needfor data exchange from aircraft-to-aircraftand aircraft-to-ground. Automated DependentSurveillance-Broadcast (ADS-B) is a data linkfor surveillance. New ideas for addedinformation (weather observations on theaircraft and 4D trajectory exchanges are twoexamples) are constantly arising. The aviationcommunity is realizing that to avoid

overburdening the aircraft with data linktransceivers, some consolidation will benecessary.

For the small airport and aircraft users, the datalink requirements revolve around automation ofunattended airports or airports withoutsurveillance. These include automatedsequencing instructions (used in conjunctionwith ADS-B and/or Cockpit Display of TrafficInformation (CDTI)), requests for runwaylighting and automated condition reports, andthe reports of conditions, active runway, etc.These items are not all currently defined on anydata link, but are most closely associated withthe CPDLC meaning of the term “data link”.The job in front of a small airport research teamis to define the unattended or non-surveillanceairport procedures that will require data linkmessages. These procedures will have to berefined and their adoption will have to beencouraged and promoted. It will then have toinvestigate current message set definitions anddefine new messages as necessary. Researchwill also involve investigation of the currentlyavailable product sets for the aircraft and theground. Where there are gaps in equipmentavailability, the economics will have to beinvestigated and investments may have to bemade to stimulate product availability.

All aspects of air traffic management willbenefit from sharing of information and fromautomation of routine actions. This creates theneed for data exchange from aircraft-to-aircraftand aircraft-to-ground, both for display to pilotsand controllers, and for input to automatedprocesses. Examples of the information to beexchanged are shown in the table. Since the datahas multiple sources and multiple users, anetwork approach to the data communication isindicated. This gives rise to a net-centric modelof how future operations will exchangeinformation.

3.1.3.2 NavigationAn expansion of the FAA’s RequiredNavigation Performance (RNP) and ActualNavigation Performance (ANP) procedures

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should be evaluated that would provide creditfor the evolving advanced technology systemsthat have been shown to provide greatlyincreased flight path accuracy with equivalentor improved safety and user efficiency. TheRNP/ANP Terminal Instrument Procedures(TERPS) and en route standards need to includenot only navigation systems but also considersynthetic vision systems with highway-in-the-sky (SV/HITS) that can provide extremelyaccurate flight path guidance. Enhanced FlightVision Systems (EFVS) can also allow the pilotto “see” the runway environment in adversevisibility conditions. The ability to highlightobstacles (deer, aircraft, ground vehicles, etc.) inthe runway environment, even in IMC, willprovide an improvement in flight safety. TheRNP/ANP improvement will be a great aid forsmall airports, especially those that do not havea precision approach now. The infrastructureimprovements will be minimized because thesafety areas could possibly get smaller. Thedetermination of RNP and ANP for anyparticular aircraft should be a calculation that aflight crew can perform. Based on the currentworking equipment on an aircraft, the flightcrew should be able to determine the RNP/ANPvalues that are available to them.

3.1.3.3 SurveillanceThere will also be an improvement in flightsafety with the implementation of ADS-B toprovide real-time traffic information andalerting on advanced synthetic vision displays.This capability is important not only in theterminal and approach phases of flight, but enroute as well. Traffic separation is always aconcern in aircraft operation. Just as the newdisplay technology benefits the aircraft in termsRNP, the display technology can enhance theflight crew’s “see-and-avoid” capability. Three-dimensional and four-dimensional analysis willbe displayed to the flight crew so that they notonly know where the traffic is, but where it willbe in relation to their flight plan path (conflictprobing and de-confliction).

The combined display of traffic plus theConflict Detection and Alerting (CD&A)

technology will assist the flight crew in “see-and-avoid”. There are issues with thistechnology that must be addressed. Hazardouslymisleading information cannot be given to theflight crew that would indicate that traffic is nota factor or that separation standards would notbe broken. There must be redundancy to ensurethat a system failure does not cause an issue.ADS-B relies on GPS technology for itsposition reports. Backup position/navigationsources are also important to traffic display aswell as CD&A. Consequently, sensor fusion isalso a necessary research area. If CD&Aalgorithms are driven by traffic informationobtained from ADS-B, as well as a secondarydevice such as TCAS, they must provide thesame answer or at the least, non-conflictinginformation. The CD&A must also be designedsuch that it does not contradict an ATC call outof traffic.

3.1.3.4 Combined VisionAnother promising technology area that hasbeen briefly investigated thus far is a CombinedVision System, which combines synthetic vision(which uses an on-board terrain/obstacledatabase) with information derived from othersensors on the aircraft. One such sensor,forward looking infrared (FLIR), is alreadycertified by the FAA for use in Enhanced FlightVision Systems (EFVS). This EFVS technologyhas been certified to provide the pilot with theability to use a Head-Up Display (HUD),showing Primary Flight Display (PFD) typeflight information and a FLIR sensor image, togo down to 100 feet above the runway -- if theFLIR shows the runway and indicates that theaircraft is in a position to make a safe landing.Research needs to be conducted to evaluateadditional sensors (millimeter wave Radar,Lidar, and others) and to pursue fusion of thesensor image with synthetic vision displays. In arecent simulation experiment, a fused FLIR/SVdisplay was shown to provide pilots withoutstanding situation awareness, even whileconducting instrument approaches in difficultIMC.

3.2 Weather SafetyIn the second targeted area, Weather Safety,research is recommended to develop systemsthat will protect the aircraft when operating inadverse weather conditions. Important goalsinclude:• Real-time Cockpit Weather Intelligence• Enhanced Weather Forecasting• Airport Weather Sensors• Enhanced Icing Safety

3.2.1 Real-Time Cockpit WeatherIntelligenceReal-time weather provided to the cockpit isnecessary to achieve improved safety for nearall-weather operation. General aviation flights,at least for piston driven aircraft, operate at thelower altitudes where the weather patterns havethe most effect. Real time knowledge of icing,convective activity, and turbulence is invaluableto the pilot. Tremendous strides have been madein providing NEXRAD (Next GenerationRadar) weather information to the cockpit fordisplay on the aircraft Multi-Function Display(MFD). The ability to provide weatherinformation via data link to the cockpit iscurrently being embraced by the pilotpopulation.

However, accessing the data needs to be mademore intuitive. The pilot workload in poorweather is much heavier, so the ability to find,access, and interpret real-time weather mustrequire minimal pilot action. Research areasshould examine resources and techniques forfusion of weather information involving theintegration of data from ground systems, aircraftsensors, and forecasts. Research should involvecockpit automation for assessment of significantweather data relative to the aircraft’s flight planand alternate airports, with assistedinterpretation and intuitive interpretation anddisplay of weather information.

3.2.2 Enhanced Weather ForecastingWork in Enhanced Weather Forecasting toimprove the forecast accuracy and capability,particularly recognizing that imprecise current

weather information is usually all that iscurrently available. The development ofenhanced weather forecasting for the loweraltitudes and the remote areas that small aircraftoften operate will have a major effect on thesafety and productivity of small aircraft.Currently, low-altitude weather forecastinglacks fine-grid data to make the adequatelyrefined forecasts that are needed along a specificflight path. As a result, when severe weather isforecast in a region, small aircraft currentlyavoid that region resulting in inefficiency and inmany cases a loss of air service.

Aircraft icing for a GA aircraft is a particularlyserious issue. Some general aviation airplaneshave equipment that permits flight into regionsof known or predicted icing. However, detailedinformation for any specific location is usuallynot available, even in real time.

The historical emphasis of weather predictionand reporting is on the movement of large airmasses and their interactions. Very little hasbeen done in the area of aviation microclimateprediction. Primary reasons have been themagnitude and cost of data collection forlocalized weather phenomena. With the cost ofsensing and computing capabilities continuallydeclining, these constraints should eventuallyend.

Obtaining truly useful aviation weatherinformation will require coordinated efforts inthe following areas:

• Analytical tools that enable the creationof predictive dynamic models ofmicroclimates

• More detailed information aboutregional weather patterns andmovements that affect microclimates

• Develop and implement higherresolution weather satellite compositedata

• Develop and install ground-based andon-board storm and icing sensors

• Availability of user-specific predictions

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• Real-time dissemination of informationand updates to all users

There are three solutions currently beingworked to improve weather data collection:

• MDCRS – Meteorological DataCollection and Reporting System –participating transport airplanes collecttemperature, wind, and position data onselected airline routes and transmit dataover ACARS or other data link services.

• TAMDAR - Tropospheric AirborneMeteorological Data Reporting systemreceived FAA Supplemental TypeCertification 6/17/04 for installation onMesaba Air Lines Saab 340 aircraft.

• More automated ground stations withimproved sensor capabilities, located atsmall airports.

The first need in this area is for a system-leveloverview of the current weather-relatedinfrastructure, and also of the research,development, and upgrades now in work.Importantly, no document currently providesthis overview considering all the manygovernment, university, and industryorganizations involved. This overview wouldserve as the first step in creating a propersystems-engineering approach to both thedevelopment and implementation of anoptimum weather information and avoidancesystem. This is a necessary step to give neededform and context to ongoing effortsthat are already bearing useful fruit along abroad range of meteorological R&D projects.

3.2.3 Airport Weather SensorsThe goal for airport weather sensors is todevelop sensors for general aviation airportsthat are affordable, enhance safety of flight, andmeet FAA requirements for commercial serviceoperations.

Of over 3,300 airports, less than 1,000 have aFederal AWOS or ASOS station. That meanssome 2,000 airports have none or limitedautomated weather sensor services and nomeans for automatic dissemination of this data

to the public. While many of these airportswould like to have scheduled service operations,the greatest constraint preventing broaderimplementation of AWOS stations that wouldqualify airports for such services is basicallyaffordability. Acquisition cost is over $100,000,and the cost of dedicated lease line connectivityfor reporting non-Federal AWOS station data tothe FAA averages over $1,000 per month persite. Re-engineering of sensors, use ofmicroelectronics, advanced algorithms, andnetwork centric communication could reducethe cost of acquisition and operation by overfifty percent.

Improved weather information along theapproach path (not just vertically above theairport), including slant range ceiling height andvisibility, is particularly important. Runwaycondition sensor technology should also bedeveloped to more accurately predict theoccurrence of runway ice, allowing for a 30% to75% reduction in treatment with chemicals [27].Factors affecting runway icing conditionsinclude runway surface color and composition,wind velocity and direction, surface moisture,atmospheric moisture content, traffic volume,amount and angle of incidence formation of ice.

3.2.4 Enhanced Icing SafetyThe first rule in general aviation icing safety isavoidance of known icing conditions. This willbe aided by improved fine-grid aviation weatherdata collection, analysis, real-timedissemination to aircraft, and fine-grid weatherforecasting. As icing incidents and fatalitiespersist for general aviation, research remainsessential in icing prevention and protection.Therefore, the goals for enhancing generalaviation icing safety are:

• Affordable and effective in-flight anti-icing and de-icing capabilities.

• Better information about thesusceptibility of wings to stall due tofrost, snow, and ice while on the ground,and the proper management of thoseconditions.

Despite years of research and engineering, theproblem of icing on general aviation aircraft hasnot been satisfactorily solved. Lacking theseresources today in general aviation, pilotjudgment is the major factor in safe operationsin icing conditions. For pilots of light airplanes,often the best decision is to not fly into possibleicing conditions, which means that flights arecancelled, making the airplane less reliable as atransportation tool. Affordable and effective de-icing and anti-icing capabilities for smallaircraft are essential areas of research. Iceadversely affects both airframes and engines.On airframes, ice adds considerable weight andaerodynamic drag while severely reducing thelifting capability of wings. Ice on propellersreduces thrust and induces dangerous vibrations.Engine inlet ice chokes off combustion andcooling air. While equipment is available formany airplanes to allow flight into known icing,no system yet exists to reliably prevent orremove ice from all aircraft surfaces and enginecomponents in the most severe icing conditions.Consequently, ice-related accidents continue tooccur each winter.

Jet transport aircraft typically have superioranti-icing capabilities because their enginesprovide substantial excess heat that is tapped toheat the leading edges of wings and tailsurfaces. These aircraft are also designed tohave high thrust in order to fly at a very highaltitude, which enables them to climb rapidlythrough the lower altitudes where icing occurs.Once at their high cruise altitudes, icing isalmost never a problem. These advantages aresimply not available for very light jets, or forlight, propeller-driven airplanes, whether pistonor turboprop powered.

The most common ice protection system forlight aircraft use pneumatic leading edges toexpel the ice or inject antifreeze solutions toremove the ice. These systems are heavy,expensive, costly to maintain, reduceperformance, and have undesirable operatinglimitations. Several exotic technologies havebeen tried with little success. Oddly,

simple and inexpensive technologies such asleading edge shields, mechanical scrapingmechanisms, electrical thin films, internalleading edge MEMS technology hammers, andacoustic drivers have received relatively littleattention. Research to explore these simpler butpotentially effective technologies may bearconsiderable fruit.

3.3 Ease of OperationsThe third target area is Ease of Operation. Thisarea is particularly important for small aircraftoperations with a single-pilot, as compared totwo-crew operation used by large airline and aircharter operations. The highest priority researchtopic in this area is Intuitive AircraftOperations. Research is recommended on hapticflight control systems (that provide sensoryfeedback to the pilot) and on intuitive displaysthat can enhance aviation safety by providingaircraft performance envelope protection. Thisresearch should also include the development ofmore affordable display media, such as head updisplay (HUD), head-worn displays, effectivehead-down displays, and synthetic voice/voicerecognition. Research directed at thedevelopment of automated flight planningcapabilities, emergency auto-land, resilientrecovery functionality, fly-by-wire control lawswith an affordable fully-coupled auto-pilot, andautomated pre-flight and weight-and-balancetechnology is also recommended.

There are three major goals under this targetarea and they include:• Enhanced Single pilot performance• Single-pilot operation• Aircraft automation

3.3.1 Enhanced Single Pilot PerformanceThe conventional focus for the enhancement ofsingle-pilot performance has been to developsystems that provide greater situation awarenessto the pilot and make the tasks associated withthe operation of the vehicle easier. This isindeed a noble goal and the benefits that havebeen realized by these efforts in a short periodof time are quite impressive. Thanks in large

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measure to the efforts of NASA AGATE andSATS projects, new technologies have greatlyenhanced the capabilities of light aircraft,including:

• Greatly improved primary flightinstruments that are more intuitive andare far more reliable than the originalmechanical instruments that theyreplace;

• GPS based navigation systems andassociated path following functions thatprovide much more accurate positionand velocity information than could berealized with older navigation systems;

• Flat panel displays showing a myriad ofinformation including moving map,graphical weather and terrain, adjacenttraffic, route management, highway-in-the-sky flight guidance aids, etc.;

• Full Authority Digital Engine Control(FADEC) that reduces the task of enginemanagement to a single lever andsophisticated diagnostic systems toidentify engine anomalies early.

Now that these new technologies are reachingmaturity, the focus of avionics developmentneeds to move beyond sophisticated situationawareness, ease-of-use technologies, andexamine how avionics can be used to addressthe inherent lack of human redundancy thatoccurs when the first officer is eliminated fromthe cockpit. One premise is that while ease-of-use technologies make the task of flying easier,thus reducing the risk of pilot distraction andloss of situation awareness, the technologies fallshort in really providing the level of oversightand human redundancy provided by thepresence of the first officer. In some instances,the automation may actually lead to dangeroussituations stemming from pilot complacencydue to over-reliance on automation. Therefore,notwithstanding modern technologies, single-pilot operation is still inherently riskier thantwo-pilot crew operation, as discussed next.

Avionics are envisioned that can fill the voidcreated by the lack of the first officer for single-pilot operation. Ultimately, the vision for thistype of automation is to provide a system thatcan participate in meaningful Cockpit ResourceManagement (CRM) with the pilot in command.In such a system, not only does the pilot haveoversight of the automation, but also theautomation is granted some limited oversight ofthe pilot. Such oversight could be manifested asterrain warnings, flight decision-makingwarnings relative to inclement weather, flightplanning and fuel management assistance, flightenvelope warnings and/or protection, andautomatic recovery from unusual attitudes. Inthe extreme case of total pilot incapacitation, theautomation would be able to assess the situationand invoke emergency auto-land capabilities.This larger vision is well beyond the scope ofany one effort, and requires considerableresearch to fully investigate all of the issues. Asa first step, the focus should be on the key initialcomponent of a system that aims to replicatefirst officer capability: an auto-flight system thatcan fly an aircraft through its entire flightenvelope, provide envelope protectionadvisories, and recover from uncontrolled flight.

3.3.2 Single-Pilot OperationIt is difficult to quantify the level of riskassociated with single-pilot operation asopposed to a two-pilot crew because statisticsdirectly comparing single-pilot operations tomulti-piloted aircraft are not available.However, some insight can be obtained fromexamining 2003 aircraft accident rates shown.Examining the type of operations relative totheir safety record, it is clear that FAR 121 andFAR 91 corporate operations are by far thesafest. FAR 121 operations are required to beoperated by two-pilot crews. Most FAR 91corporate operations use two-pilot crewsalthough, depending on specific aircraftrequirements, it may not be specificallyrequired. Comparing these operations to on-demand air taxi shows that the FAR 135operations have a much greater accident rateeven with the presence of a professional pilot.General aviation (all-types), where there is not

necessarily a professional pilot, has an evenhigher accident rate. There are several factorsthat may make FAR 135 operations moredangerous. These factors include lowerperformance aircraft with less capable avionics,the use of less capable airport facilities, and thefact that these aircraft are often flown by asingle pilot. Since multiple factors are involved,single-pilot operation cannot be singled out asthe definitive safety concern; however, it isindicated to be a factor. Rockwell Collinsperformed a pointed analysis of single-pilotoperations when they examined Cessna Citation500 accidents [28]. This aircraft is a light jetthat is approved for single-pilot operation, but ismore likely to be flown with a two-pilot crew.There have been four fatal two-pilot crewaccidents and five fatal single-pilot accidents forthis aircraft.

While no firm numbers exist on the ratio ofcrewed-aircraft to single-pilot flight hours,Collins estimates that crewed flight hours is atleast 3-4 times higher than single-pilotoperation. Since operation of the aircraftrequires a type rating and insurance companiesrequire high levels of experience in this aircraft(e.g. 2500-3500 hrs), it is reasonable to assumethat the single-pilot operators are as qualified ormore qualified than pilots of the two crewaircraft.

When single-pilot accidents are examined, onecan surmise that they would not have happenedif another qualified pilot were on-board.Examining the accident histories reveals that thepilot of one of the Cessna Citation 501 accidentaircraft was too slow on final approach. Anotherpilot lost control on departure in IMC. Oneaircraft was lost during maneuvering on a clearday. Another Citation 501 was lost during afailed instrument approach and hit a mountain.Most of the accidents involved some form ofloss-of-control and controlled-flight-into-terrain,adding credence to the need for automation toprotect the pilot from exceeding the aircraft’sflight envelope.

A trend in aviation industry continues to pushadvanced technologies and affordability frommilitary and commercial systems to generalaviation. Examples of this include avionics suchas GPS receivers, moving maps, weatherbroadcast, auto pilot, data link communications,enhanced vision system, paperless checklistsand handbooks, and most recently head-updisplays. Nevertheless, most aviation systemsoperate as independent or barely integratedsystems. While contemporary flightmanagement systems can provide significantworkload relief, they also introduce new issuesand dangers such as mode confusion, operatordetachment, compliancy, skill erosion, workloadspikes, and interface complexity. Overcomingthese issues within the context of single-pilotoperation requires fundamental improvementsto the functional capabilities of controlautomation and how it supports and interactswith the pilot.

3.3.3 Aircraft AutomationThe goal of general aviation aircraft automationis characterized as an intelligent flight deck thatpromotes the attributes of portability,affordability, safety, open architecture, seamlesscommunications, navigation, surveillance, andNAS interoperability. Objectives of automationadvancements for general aviation are to:

• Prevent loss-of-control accidents;• Provide integrated support for future

airspace capabilities (e.g. RNP, highervolume operations);

• Simplify supervision and tasking offlight control automation;

• Maintain safety of flight in the event ofpilot inaction, incapacitation, or blunder;

• Structure the roles, responsibilities, andinteraction between pilot and vehicle tocreate shared situation awareness androbust error detection and recovery;

• Reduce the need to learn and retainhighly specialized skills and knowledge;and,

• Provide an extensive foundation forintegration of future technologies.

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Research in automation for general aviationshould include open architecture, virtual co-pilot, envelope protection, fully-coupled auto-pilot, auto-land, and real time WAAS approachprocedure design.

3.3.3.1 Open ArchitectureAn open architecture for software avionics,aviation databases, and communications(including wireless) is needed to stimulate theseadvances and facilitate cockpit systemsintegration. Open architecture for generalaviation aircraft will enable the manufacture oflower cost commercial off-the-shelf automationapplications. This would permit portability ofavionics among aircraft of different types, andease of interface with on-board avionics,systems, and databases. It would facilitateaccess to standardized aviation databasesavailable on-board or via data link. Openarchitecture could enable avionics’ recognitionof its vehicle, on-board devices, sensors, andaccessible information whether static ordynamic. It should be self-certifying whenmoved from one aircraft to another, and providethe necessary FAA-qualified test results andreports. Integration of these innovations wouldencapsulate an intelligent single-pilot automatedcockpit. Research in this area should considerstandard avionics interfaces to allow real-timesharing of sensor data and database informationamong multiple avionics systems which wouldreduce redundancy of systems such asembedded GPS sensors, multifunction displays,and aviation map databases, all of which addweight and interface complexity.

3.3.3.2 Virtual Co-PilotOpen architecture for integrated avionicssystems would permit virtual co-pilot operationsto improve single-pilot safety, reducedworkload, monitoring of aircraft performance,and presentation of recommended actions forcommunication and navigation. Recent researchwith virtual co-pilot technology hasdemonstrated the potential for significant safetyimprovements through monitoring pilotperformance, aircraft systems, airspace rules,and other traffic within a self-control area. Alsodemonstrated was the potential for workload

reduction through the performance of routinetasks via the virtual co-pilot, such as flightplanning, display map-scaling, checklistautomation, menu selection, data linkcommunication of standard messages, and voicerecognition/synthetic voice, to name a few.

Voice recognition and synthetic voice (VR/SV)technology is continually being improved andthe applications are now gaining acceptance.Both technologies can be used for the controlleras well as the flight crew. VR/SV must enablefunctionality for the flight crew and controllersuch that they do not need to operate in a heads-down manner. A feedback mechanism is alsoneeded to provide assurance that VR commandsare properly recognized and that an incorrectrecognition is prevented.

Pertinent virtual co-pilot issues include flightcritical certification, performance accuracy,timely availability of data sources, and multi-modal intuitive display of information, data linkcommunication standards, and knowledge-basevs. rule-based intelligent language system.Research should be extended to include freeflight operations through every phase of flightwithin the NAS.

3.3.3.3 Intelligent Auto-Flight SystemsIn the previous section evidence was presentedsuggesting that loss-of-control is a major factorin many aircraft accidents. It is evident that thedistractions that lead to loss-of-control are evenmore significant when a single-pilot has to dealwith the situation solely. Furthermore, sincerudimentary envelope protection devices, suchas stall warning indicators, g-meters, and angle-of-attack indicators already exist; it is clear thatthe distracted pilot already overlooks thesewarnings. Therefore, it seems evident that thereis a need for a much more active system that canprevent accidents by interceding when a pilotblunders into an unsafe condition. This systemcould be envisioned as an envelop-protectionsystem with the following features:

• Full auto-flight capability with auto-throttle

• Identify and recover an aircraft fromunusual attitudes

• Identify turbulence and automaticallymodify auto-flight performance tomaintain level flight

• Recognize engine over stress and limitedfuel conditions

• Identify operational performance limitsrelative to density altitude, outsidetemperature, field length, and obstacles

• ‘Run in the background’ during bothmanual and automatic flight and provideactive envelope protection

• Identify pilot incapacitation, takecontrol, and return the aircraft to a safestate

• Emergency auto-land capabilities

3.3.3.4 Envelope Protection and AutomationNew aircraft like the VLJ have opened the jetmarket up to small business and newowner/operator pilots. The pilots that areoperating these advanced aircraft may have arelatively low number of flight hours. Tomaintain a high level of safety, a flight controlsystem with envelope protection would be veryadvantageous. A Flight Management System(FMS) could be designed that effectivelymonitors the operation of the aircraft relative toits design flight envelope and ensures that alow-time pilot does not attempt maneuvers thatcould damage the airframe. The potential for astall/spin accident could be minimized, if notavoided completely, by designing an FMS withenvelope protection. A low-time instrumentpilot could also be protected from disorientationwith a “smart” FMS.

General aviation has the highest rate of aviationaccidents due to operation of the aircraft outsideof its performance limits. This often occursduring high stress situations such as engine-out,convective weather, wind shear, and IMC.Research into automation is needed to protectthe pilot from inducing unsafe attitudes, enginesettings, and unusual rates of change. One sucharea of research should include haptic stimulusand response. The haptic system is based on themetaphor of a well-trained horse and rider. The

metaphor has two key aspects. First, the vehiclehas a “horse-like” degree of situation awareness,intelligence, transportation capability, andautonomy. And second, like a horse and rider,the aircraft and pilot interact through a multi-modal interface that includes a strong,bidirectional haptic (sense of touch andkinesthesia) component. This physicalconnection provides the operator with a naturalmeans of feeling and directing the actions of theautomation with minimal use of visual andcognitive resources. Implementation will requirefly-by-wire control laws to simply flying toautomobile-like operation. Given the generalconservatism of the industry, users, andregulators toward new flight control technology,a viable, long-term strategy must supportincremental introduction of new technologies inless critical applications and/or with knownbackup systems and procedures. Once sufficientoperational flight experience has beenaccumulated, next generation systems canincrease the functional criticality of thetechnology. The haptic system concept providesa high-degree of flexibility to tailor the human-machine relationship.

3.3.3.5 Autopilot with Auto-ThrottleAn auto-throttle is required to implement theenvelope protection described in the precedingsection, or at least the advanced version. Ifactive envelope protection is enabled, acombination of autopilot to manipulate thecontrol surfaces and an auto-throttle to controlthe engine performance will be necessary. Auto-throttle or a Full Authority Digital EngineControl (FADEC) will be needed for auto-landoperations. An affordable fully-coupled auto-pilot would resolve many of the complexitiesassociated with precision approaches by low-time or non-professional pilots. Without anauto-throttle, the pilot must give constantvigilance to the reference airspeed on approach.Combine this with cross winds and gusts, andthe ability to maintain the proper pitch directlyaffects the approach speed. Smaller airfieldswith varying runway lengths and approach glideslopes add to the complexity of energymanagement for the approach. Having an

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affordable fully-coupled auto-pilot for generalaviation aircraft could improve the safety ofVMC and IMC operations. Issues relating togeneral aviation aircraft include certification,affordability, low-weight electromechanicalcontrol devices, reliability, ease of retrofit,sensor type and interface, and fail-safearchitecture.

3.3.3.6 Emergency Auto-LandApproach and landing continues to be one of themost challenging phases of flight. Auto-land forgeneral aviation aircraft is needed to increasesafety during this phase. While pilots of allexperience levels are susceptible to an approachand landing accident, it will be the low-timeinstrument-rated pilots that drive the accidentstatistics. A real benefit to a low-time pilotwould occur when the weather at theirdestination drops below their personalminimums. Instead of a 1000’ ceiling, theweather has dropped to 200’ and the pilot is notcomfortable. The auto-land system would allowthe flight to be completed safely. Thetechnology is available to design an auto-landsystem for general aviation, but the safety needsto be proven in order to allow certification ofsuch a system. Air-carrier auto-land requiresapproval from ATC. To allow auto-landing atnon-towered airports, operational proceduresthat assure safety must be developed anddemonstrated. Consideration should be given asto whether this capability should be allowed forroutine landings, or should be permitted foremergency landings only.

In the case of an incapacitated pilot (severeillness, severe disorientation, loss ofconsciousness, loss of flight control surfacefunctionality), an attempted safe landing is ofutmost importance. Integration with a hapticsystem described earlier could provide amechanism for “sensing” that the pilot is notresponsive to desired control inputs, and thenhave the fully-coupled auto-pilot take over theflight controls. Results of recent “resilientrecovery” modeling have demonstrated that asophisticated flight management system andfully-coupled auto-pilot can successfully fly an

aircraft to a safe landing to the nearest suitableairfield with control surface damage, such as astuck rudder or flap. Such work could alsoimprove general aviation survivability whencounter intuitive flight control laws would applyand mitigate pilot induced control errors. Theonly other method for survivable emergencyrecovery is an aircraft parachute, but the aircraftsuffers damage on impact. The criterion forauto-land is to achieve a near-normal landingwith minimal structural damage (e.g. landinggear damage could be acceptable). Issuesrelating to auto-land capability includecertification for emergency use; open softwarearchitecture for ease on interface with other on-board systems, sensors, and databases, FMS,Electronic Flight Instrument System (EFIS);knowledge of the airspace boundaries, flightrules, terrain, obstacles, weather, suitablelanding areas, aircraft system health (fuel, etc.);accurate runway elevation detection (radaraltimeter) for precise flaring; and, “resilientrecovery” flight control algorithms andmanagement system to maintain flight withstructural damage.

3.3.3.7 Real Time WAAS Non-PrecisionApproach Procedure DesignWithin the FAA Flight Inspection office, theyare undertaking the enormous task of creatingand certifying WAAS approach procedures forthe over 3,000 airfields in the contiguous U.S.Until this is complete for all acceptableapproach ends of each airfield, there will berunways that lack precision approach equipmentand are inaccessible in IMC even if the aircraftis equipped with GPS/WAAS navigationreceivers. To meet the demand for generalaviation, and ensure safety of IMC approachoperation to as many runway ends as possible,research should consider airborne capabilitiesfor dynamically creating GPS/WAAS approachprocedures. It is generally accepted that thecapability for creating GPS/WAAS precisionapproaches in real-time on-board the aircraft is ahighly complex mix of accurate and up-to-dateterrain database access and certification rules,accurate and current knowledge of the airfieldrunway facilities and foliage, and complex

approach/missed approach airspace algorithmcertification for each aircraft type.

Since dynamic real-time precision WAASdesign in the cockpit may not be realistic withinthe next decade or two, an alternative totraditional protracted methods for precisionapproach design and certification, researchshould consider extending existing non-precision approach (NPA) procedure designautomation for use in the cockpit. For airportsand runway ends without a GPS/WAASapproach procedure, this technology could aid apilot in assuring a safe emergency landing to anappropriate landing area. It could also be of aidin selecting an appropriate airfield and runwayfor a safe emergency auto-landing, given theaircraft was properly equipped. Issues affectingthis technology include establishing standardsfor acceptable minimum decision altitudes forautomated real-time NPA GPS/WAASprocedure design; access to current certifieddatabases of terrain topography, airfield/runwayfacilities and topography, and obstaclessurrounding an airport; certification of softwareand algorithm functionality for designing non-precision GPS/WAAS approach procedures inreal time for each aircraft type; and,interface to an FMS.

3.4 Community CompatibilityThe fourth target research area, CommunityCompatibility, addresses the concerns of thecommunity, particularly for those living in closeproximity to an airport.

3.4.1 Small Aircraft Safety ImprovementImproving the safety of small aircraft operationsin and around small airports and in the NAS isthe critical community compatibility goal.Unfortunately small aircraft operations do notcurrently enjoy the same safety record as hasbeen achieved by airline operations. SmallAircraft Safety Improvement is the highestpriority technology area that must be addressed.This is important from a reality, as well as aperception point of view, if the SATS vision isto be achieved. Research is recommended to

develop acceptable methods for quantifying thesafety of small aircraft at small airports.Research is required to examine the benefitsderived from: a) aircraft health monitoringsystems, b) pilot training, and c) flight safetysystems analysis in all phases of flight. Real-Time Safety Health Monitoring should bedeveloped to improve aircraft safety, dispatchreliability, and to reduce maintenance cost andtime. These real-time systems can enhancesafety of flight via aircraft in-flight healthmonitoring. The development of open standardsand protocols for health monitoring systems isneeded. Low-cost, light-weight, nondestructive,unobtrusive, wireless, embedded sensors shouldbe developed for monitoring the aircraftstructure. An interface needs to be developedfor integrating information from the aircraftavionics, engine sensors, flight control andstructural stress sensors, data linkcommunication, flight management system(FMS), and auto-pilot.

Small aircraft and small airport securityconcerns must also be identified and resolved.An airport infrastructure security roadmapshould be developed in close cooperation withthe FAA and Department of Homeland Security(DHS). This roadmap must examine technologyadvances which should allow small aircraft tooperate efficiently in the NAS, includingoperations within the ADIZ, as currentlyencompasses Washington, DC. Small aircraftand small airport security infrastructurerequirements need to be evaluated. Thedevelopment of an encrypted ADS-B basedsecurity identification system for small aircraftappears very promising and should be quicklypursued, including conducting field tests anddeveloping standards for airborne small aircraftidentification procedures.

3.4.2 Small Aircraft and Airport SecurityTo improve the operating economics of smallaircraft and the users of small airports,expedited flight through secure airspace is veryimportant. The cumbersome procedurescurrently required to fly in or through theWashington ADIZ are an extreme example, but

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it is anticipated that other similar airspace mayalso be defined in other locations. Onetechnology that can provide the necessarysecurity, without being unduly burdensome, is asecurity technique that can provideauthentication of a given aircraft and its pilot.NASA Glenn Research Center has sponsoredresearch to demonstrate this technique, using theUAT data link.

The operational concept is that the aircraftavionics (the ADS-B equipment) will contain atamper-protected secret key. The pilot enters aPIN upon initializing the avionics. As theaircraft flies, the ADS-B transmissions would be“signed” using the avionics key and the PIN.This would be done using standard andestablished authentication algorithms. Theground (or airborne enforcement) equipmentcan verify the signature by knowing the key andPIN used. As a participant flies into an airspace-requiring authentication, the surveillance systemwould automatically recognize the ADSBreports as authentic and indicates such to thecontroller or enforcement official. It would thenassure that the aircraft and pilot are on theapproved or “vetted” list. It would not benecessary to make voice contact to be clearedinto the area. In present VFR operations, voicecontact is required, and many pilots have tocircle outside of the airspace until they canbreak onto the frequency or for their flight planto be verified.

The advantages will be primarily achieved bysmall aircraft users that wish to traverse theADIZ, or by users of small airports near orunder the ADIZ. The new capability will saveflight time, and the pilot will not have to contactas many players in the system (possibly none).As mentioned before, it is anticipated that otherairspace with security restrictions will develop,particularly with the increase of small aircraftusage. With automatic authentication possible, itwill be more practical for the NAS designers togenerate corridors through secure airspace,which will further increase the value to smallaircraft operators so they do not have to

circumnavigate the secure airspace if it is ontheir path of flight.

Research in this area will involve the drafting ofdetailed operational changes and working withthe Department of Homeland Security (DHS)and with the FAA to come up with an agreeableset of procedures. Once the agencies agree onthe operational details and approve them, thestandards bodies will recognize it as anoperational need and can get it into thestandards so that equipment can be certified.The process of establishing the operational needand adopting the standards takes about five years in general. Economic analysis must also bedone to assess the cost (to manufacturers) of thechanges and whether they will provide themarket with capable equipment.

3.4.3 Aircraft NoiseThe methodology to study noise and emissionimpacts of aviation activity is well understoodfor airport and terminal area procedures [29].Less research has been done at predicting noiseand emissions in the en route phase of flight. Anationwide assessment of noise and emissionimpacts of aviation related activity is needed.This analysis requires consideration of displacedmodes of transportation and characterization ofinduced intercity trips. The analysis requiresspatial representations of where sources ofpollution exist and their dispersion in the loweratmosphere.

New technology aircraft can have relativelysmall noise impacts at airport through acombination of advanced engine technology andcarefully planned procedures. A preliminaryassessment of very light jet noise impacts atairports determined that rural airport noisecontours could increase 1-3% if SATS VLJtechnology is widely accepted. Metropolitanairport noise contours could increase by 4-7%.It is important to put these numbers inperspective. The contours of metropolitanairports like Teterboro in New York could seereductions of 40% in their noise contours if allStage 2 technology aircraft are phased out. Newaircraft technologies that encourage replacement

of older and noisier vehicles will help reducethe noise impacts at some airports.

The challenges caused by aircraft noise are veryclear:

• Environmental concerns drive manylocal airport decisions to accept smallaircraft

• Aviation activity is generally perceivedas a large source of pollution.

The increased use of small community airportswill require that the noise impact be minimized.The reduction of engine and airframe noisecontinues to be a subject for considerableresearch. In order to be applicable for SATStype aircraft, additional noise reductiontechnology development needs be focused onthe quest for quieter small aircraft. For anygiven airframe, significant noise alleviation canbe achieved by using advanced approach anddeparture trajectories. Steeper, curvedtrajectories can significantly reduce the noise“footprint” and avoid noise sensitive areas.

3.4.4 Aircraft EmissionsIn addition to noise, research on small aircraftemissions also should be conducted to minimizethe impact on the community. Because smallaircraft operations are very diffuse, theircontribution to the air quality concerns for agiven community may be minimal, but thesituation as a whole should be examined.

The contribution of small aircraft emissions tothe overall global system should be evaluated interms of the location where the emissions aredeposited (altitude, latitude, longitude), theamount of the emissions, and the time of thedeposit.

3.4.5 Small Airport Land Use Impact andInfrastructure AssessmentThe goals of the efforts in the area of airportinfrastructure include:

• Develop and validate procedures andtechnologies to further increase capacityof small airports

• Examine the safety of proceduresdeveloped in part (a) towardsimplementation as part of the NGATSintegrated plan

• Study and recommend the appropriateairport infrastructure improvementsneeded to support a distributed smallaircraft transportation system capable ofproviding service to 3,400 publicairports.

The Danville demonstration of the SATSprogram provided strong anecdotal evidence ofcapacity gains at non-towered airports usingflight deck coupled with satellite and airport-based surveillance technologies. The saturationcapacity of a single-runway airport without acontrol tower under Instrument MeteorologicalConditions (IMC) varies from 3 to 5 aircraftarrivals per hour and 10-12 departures per hour.The capacity of the same airport with ADS-Band High-Volume Operations (HVO)technologies demonstrated by the SATS Project(assuming 100% fleet equipage) could increaseto 9-13 arrivals per hour and up to 18-22departures per hour. The NGATS integratedplan is to increase the capacity of the NASbeyond the 30% proposed by the FAA in thenext ten years. Procedures developed by theSATS research and implementation vision couldhelp achieve that goal.

3.4.6 Real-Time Safety Health MonitoringSystemsThe goal of real-time safety health monitoringsystems area is to develop systems to monitorthe overall health of an aircraft in real-time,report and advise of critical trends and routinemaintenance actions, interact with the flightmanagement system for optimaland safe flight performance and data link healthparameters to maintenance centers andrepositories for action and archive. Proposedresearch will develop an affordable in-flightaircraft health monitoring system in cooperationwith engine, avionics, and airframemanufacturers that provides evaluation andassessment of overall aircraft health andrecommended maintenance actions based on

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centralized data collection, archiving, andanalysis of a population of general aviationaircraft.

Commercial and military aircraft manufacturershave led the areas of engine health monitoring,health and usage monitoring systems, andstructural fatigue monitoring sensors. The trendin general aviation toward digital avionics,digital sensors, and integrated systems yields anopportunity for also improving the healthmonitoring of the general aviation aircraft in asimilar manner. The current practice in industryand the FAA requires the scheduledreplacement or refurbishment of parts based onhours of operations, visual inspection of wear,chemical analysis of fluids, and other diagnosticmeasures. These practices are largely successfulfor continued safe operations, but do notnecessarily contribute to a body of knowledgethat could lift general aviation to a higherplateau of maintenance performance.

Technology is already in place for in-flightdigitally sensing many critical piston enginecomponents and graphically presentingperformance parameters and trends to the pilot.Self-diagnostic routines are also operatingwithin individual avionics systems. Reportingand archiving of these parameters while in-flight to a centralized processor for furtheranalysis, reporting, and integration with a FMSdoes not presently exist. Furthermore, sensorsfor monitoring control surface stress and controllinks stress in-flight do not exist for generalaviation, thus are an opportune area foradvanced research. Such aerodynamic stressmonitoring could enhance safety by detectinganomalous control surface/linkage behavior andrecommendation of alternative pilot-controlresponses.

The other area of vital importance is anorganizational element involving the engine,avionics, and airframe manufacturers in thecollection and analysis of these data. Such anorganic system of automated data collection,analysis, and reporting could lead to designrefinements to improve overall reliability,

failure prediction, failure mode correlation,averted unsafe operations, and reducedmaintenance and operating costs. Considerationshould also be given to monitoring of backupsystems and elimination of false alarms in asafety health monitoring system. This researchis all the more important due to the longer andharder use of general aviation aircraft thandesigned. The cost of maintenance, repairs, newaircraft, fuel, and operation contribute to theextended use and service of an aging fleet.

A technology developed in the SATS projectknown as the Advanced Data Fusion Processordemonstrated the potential for a centralized on-board processor to record digital data streamsfrom many standard aircraft interface types inreal-time, and provide key data simultaneouslyto other avionics devices and display systems.Such a system would be needed on the aircraftto integrate with existing avionics, EFIS, FMS,airframe stress sensors, and data link radio.Real-time data link of health parameters wouldnot be necessary but could be used for reportingimminent failure modes and scheduling of time-critical maintenance actions.

3.4.7 Small Aircraft Ride QualityAnother area of major concern that can impactthe desirability of the SATS concept is ridequality. Small Aircraft Ride QualityImprovement needs to be addressed. Today,passengers often find the ride quality of smallaircraft to be significantly inferior to that oflarge commercial transports. This occursbecause small aircraft are designed with lowerwing loadings (which are susceptible to gusts)and they operate at lower altitudes where theatmosphere is more turbulent.

Research should be conducted to evaluate theimprovements that may be possible with a RideControl System (RCS). Most RCS research todate has been carried out for military aircraft, orfor structural load alleviation in largecommercial transports.

RCS systems are known to perform best with“predictive” information that is obtained by

measurement of atmospheric gusts ahead of theaircraft. The potential for developing “look-ahead” sensors to detect gusts prior to aircraftencounter needs to be examined. High-fidelitydynamic models need to be developed forrepresentative new aircraft, e.g. VLJ’s. TheRCS research should focus on an affordablesensor/actuator suite, including solid stateIMU’s, short-range look-ahead Lidar, andlimited authority active flight controls. RCSalgorithms need to be developed and theachievable improvement needs to be quantified.Flight testing will undoubtedly be required forRCS validation and pre-certification. It is alsorecommended that the potential for active seatcontrol technology be examined.

4 SummaryIn late 2005, the National Institute of Aerospacegathered national experts from industry,academia, and state organizations to develop anational strategy for research and developmentto achieve the Small Aircraft TransportationSystem (SATS) vision of safe, reliable, andaffordable air transportation for everycommunity in America. That strategy calls forcontinued research and development in thefollowing areas:

Service ReliabilitySATS integration into the National AirspaceSystem (NAS) was identified as the highestpriority technology advancement that must beworked. Within the current NAS, a SATStechnology equipped aircraft with advancedflight deck technology comparable to today’scommercial airliners would be routinelyvectored around by air traffic control to avoidpassing through higher density traffic areas.These unnecessarily circuitous routes increasefuel usage, waste time, add to operatingexpense, and result in increased ticket prices.Procedures to provide recognition of thecapabilities possessed by SATS equippedaircraft and special routes for SATS equippedaircraft through congested airspace (whereequipped aircraft can take the responsibility for

self-separation) need to be developed and fieldtested, in close cooperation with FAA.

Weather SafetyResearch is recommended on systems that willprotect the aircraft when operating in adverseweather conditions. The ability to provideweather information via data link to the cockpitis currently being embraced by the pilotpopulation. What is needed now is thedevelopment of smart systems that can interpretall the available weather information quicklyand provide timely advice to the pilot onintuitive displays, especially when the pilotworkload is often high.

Enhanced weather forecasting methods arenecessary that can improve forecast accuracy,particularly at the lower altitudes and for theremote areas where small aircraft often operate.Technology enhancements to provide fine-gridweather forecasting for lower altitudes andremote areas will contribute directly toimproved flight path efficiencies, reduceddiversions, and uninterrupted continuity of airservice.

Accurate airport weather sensors are neededwhere SATS aircraft will be operating.Affordable technology solutions should beresearched that focus on advanced AWOS andrunway surface condition sensors. This researchshould also include sensors that measure thevisibility and ceiling along the intendedapproach path.

Aircraft icing continues to plague the operationof small aircraft, since they typically operate atthe lower altitudes where icing occurs. Researchis needed focusing on the development ofimproved icing forecast capabilities, icingdetection, icing prevention, and efficient andaffordable icing removal systems.

Ease of OperationThis research area is particularly important forsmall aircraft operations with a single-pilot, ascompared to two-crew large airline operations.The highest priority research topic in this area is

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to develop more intuitive aircraft operatingsystems.

Research is recommended on haptic flightcontrol systems (that provide sensory feedbackto the pilot) and on intuitive displays to enhanceaviation safety by providing aircraftperformance envelope protection. This researchshould include the development of moreaffordable display media, such as head-updisplays, headworn displays, head-downdisplays, and synthetic voice/voice recognitionsystems.

Research directed at the development ofautomated flight planning capabilities,emergency auto-land, resilient recovery offunctionality, fly-by-wire control laws with anaffordable fully coupled auto-pilot, andautomated pre-flight and weight-and-balancetechnology is also recommended.

Community CompatibilityThis area addresses the concerns of thecommunity, particularly for those living in closeproximity to an airport. Small aircraft safetyimprovement is the highest priority technologyarea that must be addressed. Research isrequired to examine the benefits which can bederived from:

• highly integrated aircraft healthmonitoring systems,

• improved pilot training methods,• a rigorous system safety analysis which

examines all phases of small aircraftflight operation.

Small aircraft and small airport securityconcerns must also be assessed and resolved, inclose cooperation with the FAA and theDepartment of Homeland Security (DHS). It isimperative that this assessment includes anexamination of the potential technologyadvances that can allow small aircraft to operateefficiently and securely in the NAS, includingoperations within an Air Defense Identification

Zone (ADIZ), as currently encompassesWashington, DC.

The challenges caused by aircraft noise andemissions can also have an impact on thedesirability of increased small aircraftoperations at previously little used communityairports. Aviation activity is generally perceivedas a significant source of pollution, i.e., bothnoise and emissions. If not addressed, theseenvironmental concerns can inhibit many localairports from accepting small aircraft,particularly jet aircraft.

5 References1. Cooke, S; Viken, J.; Dollyhigh, S.;

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Distributed On-demand Air Transportation Using Small