Search

The effects of large GPS pseudorange bias errors and large absolute target location errors can be removed almost entirely from a guided weapon incorporating GPS updates in its Kalman filter by utilizing GPS bias states following a high quality terrain scene. Specifically, target relative bias states are added to the Kalman filter, and these states provide an accurate estimate of the total GPS bias after the terrain scene update is accepted by the Kalman filter. The performance of two different bias state configurations, one having three states and the other seven, is analyzed by means of a covariance simulation. The scenarios investigated include short and long terrain scene to target separations, both with and without the presence of high-powered GPS jammers and a softwareimplemented satellite constellation freeze. It is found that because of its virtual elimination of the pseudorange and absolute target location errors, and its affordability when compared to a terminal guidance seeker, the relative GPS bias state implementation is a viable precision strike candidate.

The U.S. Navy, through a contract with MYSTECH ASSOCIATES, INC., has developed an advanced proto-type navigational system called MATCH-NAV, which utilizes a mini-computer to provide automated own-ship geographic position in inshore, coastal navigation situations. Conceptual development of MATCH-NAV has demonstrated the capability to provide ownship position display on digitized nautical charts, with overlay of the chart data on a radar Plan Position Indicator (PPI). Future plans include utilization of the MATCH-NAV concept in design of a completely automated Ownship Position Display having stored nautical chart capability, which can accept navigational data inputs from such ship's sensors as Loran-C, Omega, radar and other precision electronic navigation systems, including satelite systems. The goal—to provide continuous, accurate, real-time visual display of ship's position in restricted coastal waters. This paper discusses the MATCH-NAV concept and its potential applications in future inshore navigation.

The Federal Aviation Administration Technical Center has been actively pursuing the investigation of various types of RNAV systems for helicopter IFR operation as part of the FAA's Helicopter Operations Development Program. Emphasis has been placed on the evaluation of LORAN-C, but data has been simultaneously collected on VOR/DME RNAV, and Omega system also. Flight test data has been collected, using both fixed and rotary wing aircraft, in the Gulf of Mexico, offshore New Jersey/Baltimore Canyon area, Appalachian areas, and on the Northeast Corridor experimental RNAV route. Most of the data collected to date has been concerned with the use of LORAN-C for enroute navigation purposes, and comprehensive reports are being prepared by the Technical Center on these efforts. The next phase of data collection will concentrate on the use of LORAN-C for non-precision approach applications.

The technology of area navigation (RNAV) has been available to our industry for almost thirty years. The manifestation of this technology in the form of airborne navigation systems capable of performing area navigation procedures in an operational environment has a history of well over twenty years. The obvious question of “Why, then, aren’t area navigation procedures an integral part of our National Airspace System?” has an almost equally obvious answer, “What procedures and what environment?“. Distant history notwithstanding, tremendous strides have been made in generating an answer to the latter question, sparked in great measure by the 1972 Area Navigation Symposium and the RNAV Task Force Report [Ref. 11. This current paper presents a status report on some of the accomplishments of the past three years in support of the efforts of the FAA in establishing a national system ef RNAV routes and ATC procedures. The ultimate objective of these efforts is to develop a data base suitable for the integration, in an evolutionary manner I as outlined in the RNAV Task Force Report, of the concept of RNAV into the National Airspace System (NAS) in a manner that will be of identifiable benefit to both the airspace users and the ATC system. To some degree this paper is a supplement to a previous paper presented at the June 1974 ION conference [Ref. 21. While that 1974 paper covered a variety of RNAV related subjects ranging from error analysis simulations to the establishment of avionics accuracy standards, this present paper will concentrate more on the operational aspects of area navigation, with particular emphasis on the evaluation of terminal area route design, ATC controller procedures, and pilot/RNAV system functions and performance criteria. While the programs discussed in this paper are, for the most part, being performed under FAA sponsorship, the results are still preliminary and the data collection and analysis is continuing. For this reason any results contained in this paper do not represent an official policy or position by the FAA, but are presented in the interest of exchanging technical information. Any opinions or philosophies observed herein are uniquely those of the author.

the design of an inertially aided radio navigation system using a scanning DME interrogator set is discussed, and flight test performance data of this area navigator and of the scanning DME subsystem are presented. Under poor geometric conditions and with 3°/sec turn maneuvers the 1–sigma position uncertainty is about 100 m. In an all–DME standby mode the maximum navigation error was less than 700 m. The navigation system is suitable for area navigation on parallel airlanes. Some operational problems are touched upon.

This paper reports on a flight evaluation of Loran-C which was part of a long range study of area navigation systems for general aviation. Tests involved two different Loran-C receivers, 6 different aircraft, and a variety of antennas. Uncorrected position fixes were typically accurate to one quarter mile. With measured corrections, repeatability was good to within 200 ft. Signal reliability was 99.7%. The receiver was not sensitive to atmospheric noise. The time difference grid demonstrated a long term stability of 0.3 microsecond. Vertical whip and ADF E-field antennas were found suitable for airborne use. Loran-C was found satisfactory for instrument approaches to runways at general aviation airports where published latitude-longitude coordinates were available. Accuracy was further improved by using locally measured Loran-C time difference coordinates.

a unique aspect of the San Francisco Experimental Vessel Traffic System has been its extensive use of real time automatic processing technology. Automatic detection and tracking of vessels in radar coverage areas has successfully been accomplished even in the presence of clutter. Vessel movement information has been extracted, presented to operators on computer-animated displays, and traffic analyzed both automatically and at the request of operators. But these demonstrated capabilities should be employed only as a guide to the design of future systems and not interpreted as a literal prototype configuration. Future system designs should assume traffic will be controlled, rather than advised. Risk analysis based upon port geometry, traffic levels, and minimum turning radius can contribute to assessing deployment priorities. Vessel routing should be constrained to follow narrow tracks rather than broad lanes. A minimum configuration would be based upon a computerized Vessel Movement Reporting (VMR) system. Data entry and retrieval terminals could be available within the maritime community. Information, including guidance, could be selectively distributed to active ships via a novel multiplexed television transmission. All radar configurations would include automatic detection and tracking equipment. Finally, area navigation systems could be integrated with VTS. The opinions expressed in this document are those of the author, presented in the interest of stimulating discussion, and they do not necessarily reflect the views of either the Applied Physics Laboratory or the United States Coast Guard.

Area navigation (rnav) provides freedom for establishing courses. This type of system allows the airplane to proceed via navigational guidance to almost any geographical position without having to overfly a radio navaid. This capability requires ingenuity for charting since many routes flown by RNAV-equipped aircraft do not fly on published courses, but prefer to go present position direct to their destination.

this paper reports on a study which compared the expected cost and performance of Differential Omega with that of Loran-C and VORTAC for general aviation area navigation. Analysis is directed toward a comparison of the systems with respect to specified performance parameters and the cost-effectiveness of each system in relation to the specifications. Loran-C offers the highest performance with respect to accuracy. Differential Omega requires the least expenditure. It was found cost ineffective to attempt to obtain complete coverage by expanding the existing VORTAC system.

This paper describes the design and flight test results of an experimental Global Positioning System receiver installed in a general aviation aircraft. These tests were part of a GPS test and evaluation project conducted for the Federal Aviation Administration by M.I.T. Lincoln Laboratory. The purpose of the project was to design a GPS C/A-code receiver that: 1) meets the current FAA requirements for two-dimensional area navigation (RNAV) systems, 2) employs techniques which could potentially lead to low-cost commercial avionics, and 3) is operationally compatible with existing ATC procedures and aircrew practices. Novel features of the design are: 1) the use of a dual-channel C/A-code receiver, and 2) the tracking of all visible satellites in view rather than a minimum set of four satellites. The system employs two DEC LSI-11/23 computers, one to perform position fixing and receiver control, and the other to perform navigation and data recording tasks. Pilot displays include a conventional course deviation indicator (CDI), omni-bearing selector (OBS), and intelligent control and display unit (CDU). The GPS receiver was flight tested at a large urban airport, at several small general aviation airports, and over mountainous terrain. The horizontal system accuracy during typical aircraft flight profiles was measured to be 333 feet (95% confidence). This level of accuracy meets the FAA's current accuracy requirements for two-dimensional area navigation systems and is consistent with future navigational accuracy requirements.

Area Navigation (RNAV) is a concept that enables an aircraft to fly directly from desired origin to destination without the need to overfly VORTAC stations. Area navigation systems include primarily VOR/DME dependent systems, although self-contained systems (such as INS) and hyperbolic systems (such as OMEGA) are also included as part of the overall concept. These systems may also include a vertical capability (VNAV or 3D) and time control along a flight path (4D). The current use of RNAV in the National Airspace System (NAS) includes a number of routes and procedures and airborne systems with a wide range of features and capabilities. Unlike many of the elements of the upgraded Third Generation ATC system, RNAV does not require any major technological developments. However, to achieve the full benefits of RNAV, a phased implementation plan is required that is favored by the users and manufacturers and the FAA. An Area Navigation Symposium of February 1972 revealed diverse interpretations of the capabilities, limitations, and benefits of this concept. Subsequently, an FAA/Industry Task Force was formed and the recommendations of this group, the RNAV Task Force Report [l], provided a three-phased implementation plan which includes specific recommendations for both ground and airborne systems. This report also raised a number of interrelated issues which must be resolved prior to the development of new avionics standards or other system planning documents, and ultimately, the full-scale implementation of area navigation. The primary impact of the Task Force recommendations result from increasingly stringent system accuracy and functional requirements, both enroute and in the terminal area. These requirements, when viewed in total, suggest the necessity of a close examination of RNAV system error elements and related avionics issues. Each of these issues impacts any attempt to quantify avionics standards, separation standards, and ground system NAVAID support. This paper presents some preliminary results of an effort to provide substantiating data for the Task Force recommendations. The specific area that is addressed is the performance of area navigation systems as compared to present and recommended future requirements. Very limited flight test data have been obtained thus far, and therefore the results should be interpreted accordingly. The results in this paper do not represent an official policy or position of the FAA, but are presented in the interest of exchanging technical information.

A computer based positioning system which combines data from radio navigation aids, the Transit satellite system and a network of underwater, acoustic transponders is described. Particular emphasis is placed on the acoustic subsystem and its integration into the navigation process. The system has been developed by the Magnavox Co., Advanced Products Division and is currently being used for drill rig positioning in the North Sea. A typical operational scenario is described and results from recent applications are discussed.

The tragic loss of an Air India jetliner off the coast of Ireland on June 21, 1985 resulted in an operation that illustrated the state-of-the-art systems and techniques used in deep ocean integrated positioning and navigation. The aircraft debris was spread over a 30 mi2 stretch of ocean, in depths of over 6,700 ft. The search and recovery effort required the use of both subsea and surface-based navigation equipment for accurately logging the positions of hundreds of pieces of debris. A microcomputer-based integrated navigation system (called ALLNAV), engineered, built, and operated by Eastport International, was used as the primary navigation system. ALLNAV was used for positioning the SCARAB Remotely Operated Vehicle, working on the seafloor, and the support ship, JOHN CABOT, above. With the integrated navigation system processing both acoustic positioning data and radio positioning data, the lat/long locations of all located debris were determined. This paper will address the requirements of, and equipment and techniques used for, subsea integrated navigation. The application of integrated navigation equipment on the Air India operation will be used as a case example.

A system is described which relates to the FAA's developmental Discrete Address Beacon System (DABS). However, the DABNLS is an integrated system and would provide not only air traffic control surveillance data and a two-way data link (including ground derived traffic advisories) of DABS, but it would also provide precision area navigation and versatile landing guidance with a full Category IIIc capability. Further, its transmissions include three-dimensional position data on all aircraft, thus supplying simple straight forward means for a cockpit traffic environment display on an effective and economic collision avoidance system with horizontal as well as vertical escape maneuver capabilities. For the enroute structure the DABNLS would utilize a single pair of L-band frequencies for the discretely addressed up-link interrogations and down-link replies. The ground facility would make precise azimuth and range measurements on the bi-phase coded reply pulses, and, with the reported altitude data, digitally process the data to obtain the aircraft's latitude/longitude and other parameters. This data is broadcast on the following interrogation for navigation by the addressed aircraft, and for collision avoidance purposes by all other aircraft. The ground facility uses the data for ATC purposes. Multiple channels would be used in the terminal areas, each with the addition of elevation facilities for landing guidance. Substantial economies would be accrued with both ground and airborne equipment, as well as added operational capabilities, with implementation of DABNLS. Even a single channel airborne transponder would provide ATC surveillance, area navigation, and collision avoidance for the smallest aircraft throughout the country, and make practical for the first time the longstanding FAA desire of surveillance of all aircraft.

A minimum of four GPS range measurements or two Loran-C time differences are normally required for a position solution for en route navigation, area navigation, and nonprecision approaches. This paper describes a new technique that hybridizes GPS and Loran-C used in the pseudorange mode to process efficiently all available navigation information. Emphasis is placed on combined GPS and Loran-C timing, both for the ground/space facilities and the user. The hybrid system has the potential to solve the GPS and Loran-C integrity problems; more range measurements are available than are required for the navigation solution.

During the summer of 1979 a flight test program was performed in the western U.S. evaluating Loran-C as a nonprecision approach navigation aid. The objectives of the program were to measure the accuracy and operational suitability of Loran-C in mountainous areas at low altitudes. The equipment used in the test was a commercially available TDL-711 Micro-Navigator built by the Teledyne Corporation. The equipment was installed in a twin engine Piper Aztec. The controls and displays were located in the cockpit where they could be operated by the pilot or copilot. The pilot used the guidance provided by the Micro-Navigator as the sole means of navigation during the instrument approach. Tests were performed in visual meteorological conditions with the copilot watching for traffic and obstacles. Independent aircraft position data was recorded using the Remote Area Precision Positioning System (RAPPS). This system uses multiple L-band range measurements to transponders placed at known ground locations. Data from both the Micro-Navigator and RAPPS were recorded on a microcomputer-based data recording system located in the aircraft cabin. The results of the tests showed that the Loran-C signal-in-space was stable and dependable at all altitudes flown in the test. Significant errors were observed in the conversion of the received time difference values into position and guidance signals. The primary cause of these errors was traced to the propagation model used in the navigation processor. These errors were generally constant in each location, but changed significantly depending upon the Loran-C triad. The errors occur primarily in areas where the distance difference between stations is several hundred miles. Selection of the wrong triad or reversion to an alternate triad during station outages could produce guidance which is in error by several thousand feet or more. However, improved propagation modeling or procedural changes show promise of reducing errors to a point where RNAV accuracy standards can be achieved.

The world-wide Omega navigation system, used in conjunction with locally-derived differential Omega updates, promises to provide the position-fixing accuracy and reliability required 1.) by commercial aircraft for area navigation in even heavily-trafficked terminal locales, 2.) by military aircraft for the successful execution of the vast majority of tactical missions, and 3.) by space shuttle and similar vehicles for re-entry navigation during the post-blackout portion of flight. A mechanization of the differential Omega concept is presented which provides maximum flexibility, allowing users to determine their positions with circular (rho-rho), hyperbolic, or pure differential mechanizations and yet does not require the differential ground subsystem to contain an expensive, highly-accurate oscillator which is normally associated with rho-rho capabilities. The hardware and software implementations are outlined and a rationale for the particular navigation and updating mechanization selected is presented. It is shown that while skywave propagation variations and local oscillator off-sets are not separated by the ground subsystem, this ambiguity need not introduce errors to user aircraft. In fact, users operating in the circular mode can generally achieve greater accuracy than for a purely hyperbolic mechanization in which all clock errors were eliminated. The implementation described is incorporated as a selectable mode of operation in the Omega subsystems to be delivered by Bendix Navigation and Control to the FAA for its differential Omega evaluation program.

Texas Instruments has developed a multiplexing GPS receiver that has many of the advantages of a continuous receiver at the low cost of a sequencing receiver. The multiplexing concept is explained. The receiver architecture is described. Advantages of multiplexing over the conventional receiver are highlighted. Applications of the multiplexing receiver to meet requirements now being met with single-channel, two-channel, and five-channel sets are discussed. Data comparing the performance of this multiplexing to conventional approaches are presented. A multiplexing GPS receiver solves difficult problems. Several of these applications are presented, including angle determination, single-channel differential GPS, area navigation and precision approach, and geodetic surveying. All applications examined have yielded a unique advantage with the multiplexed GPS receiver over a conventional GPS receiver.

Sixteen pilots of two widely different experience levels were flight tested in a Beechcraft Twin Bonanza on an area navigation task involving 3-D approaches having two levels of navigation procedural complexity. Two types of displays were used for level-ff at MDA, command leveloff and an altimeter. The four recorded performance measures were vertical steering, horizontal steering, airspeed control, and procedural accuracy. The less complex approach procedures (Simplified) resulted in better performance on all four recorded measures than the more complex procedures (Standard), However, no reliable performance differences were evident between levels of pilot experience and types of leveloff displays. In comparison with previously assumed values of flight technical error, Standard Procedures generally yielded larger errors, and Simplified Procedures generally smaller errors.

Airborne OMEGA navigation technology is now entering its third generation. The first generation “OMEGA” offered affordable, worldwide navigation, principally in the North Atlantic and other oceanic areas requiring Sole Means of navigation certification. The second generation “OMEGA/VLF” featured maturing software and improved signal reception and handling characteristics which enabled it to meet the more stringent RNAV certification requirements. The third generation “OMEGA/VLF NAVIGATION MANAGEMENT (NMS)” now combines OMEGA/VLF navigation information with a variety of position sensor inputs, including; VOR/DME, DME/DME and GPS. The combination of advanced technology, mature OMEGA software and multiple position inputs now offers a cost effective, reliable and exceptionally flexible navigation system which satisfies a wide range of current and future navigation needs.

On October 9, 1981, a Supplemental Type Certificate for airborne, en route, IFR use of Loran-C was awarded to the State of Vermont following completion of a flight test program by the Transportation Systems Center, Research and Special Programs Administration of the U.S. Department of Transportation. The certification of a Beechcraft E50 aircraft equipped with a Loran-C navigator, is the first ever granted for use of Loran-C in the National Airspace System and culminates a four-year federal-state evaluation program. This paper describes the systematic approach leading to the award. It includes a thorough examination of the certification process, the accuracy requirements described in the Federal Aviation Administration's Advisory Circular 90–45A “Approval of Area Navigation Systems for Use in the U.S. National Aerospace System,” the organization of the program, the preparation of a flight test plan, the collection of the data base, the analysis of the data, and resulting conclusions.

The office of aeronautical Charting and Cartography (NOS, NOAA) is responsible for the production and maintenance of aeronautical charts and chart related products. The maintenance of visual aeronautical charts is assisted by airborne surveys of charted areas within the United States. These surveys permit current inspection and editing of data portrayed on the charts. This paper describes the theory, development, and use of a Computer Generated Area Navigation (RNAV) Waypoint Grid System for airborne surveys. Control for these surveys is provided by aircraft equipment utilizing the VOR/DME navigation facilities of the National Airspace System. Bearings and distances (waypoints) from existing facilities are fed into RNAV equipment to create the survey grid. These waypoints are generated by a computer program using coordinate search and geodetic computation techniques from a navigation facility data base. The resultant waypoint grid data, in a form easily used in the aircraft's RNAV equipment, provides accurate position and guidance information for the survey. This method may fulfill the control requirements for other airborne surveys.

A method of determining an observer's terrestrial latitude and longitude is proposed which, once the altitude observations are made and corrected to true altitudes, can be performed entirely on a mini-computer.

IN DESCRIBING the projected ground based navigation environment for the period 1965 to 1975 expected to exist within the United States, not very much of a crystal ball is needed. For a variety of reasons, some good, and some open to criticism, ground based navaids in use by aviation today appear to have changed slowly. After all, it. is now the 34th anniversary of the four-course range, and it is still with us. It is simple to take this situation and consider it a horrible example of FAA backwardness. But this is an oversimplification of the grossest sort. Although we have been labeled backward in some respects, there are other reasons why navigation aids suitable for use in civil operations change slowly. This is not the time to explore these reasons with you detail, although I can touch upon them briefly. They involve the very nature and role of aviation in our economy. The fact that our system of air navigation and traffic control must satisfy the needs of many diverse elements is a factor, as is the conservative approach associated with the desire for tried and proven techniques to achieve a high order of operational reliability on a dayto- day basis. This factor is one which the airline passenger at least is willing to welcome.

In 1969, by specifically including 'pilotage error' in the error budget for area navigation system certification, the Federal Aviation Administration legally attached economic premiums and penalties to human as well as equipment performance in man-machine system design. To establish the accuracy of use and freedom from pilot blunders associated with systems employing various configurations of displays and controls requires both simulator and flight experimentation. An automatically adaptive cockpit side task provides a saturating level of pilot workload and allows the sensitive, orderly, and statistically reliable measurement of a pilot's residual attention as a common metric for navigation and control system assessment. A simulation experiment employing this measurement system compared pilot performances as a function of the number of waypoints that could be stored in an airborne area navigation (RNAV) computer (1, 2, 4, or 8) and the type of manual flight control system used (normal flight control versus maneuvering performance control). (Author Modified Abstract)

General aviation has become the major user of the airspace in the United States, and will continue as an increasingly predominant airspace user as time goes on. Thus future programming must take into consideration more and more the impact of general aviation on the control of air traffic, and in particular its inherent need for flexible flight routes between many points on the surface. A significant requirement for aircraft flying over multiple routes connecting virtually unlimited combinations of departure and destination points and for the efficient control of high density traffic is that pilots can perform area navigation. Airborne equipment is now available which provides accurate area, multiple track, navigational flexibility. During the remainder of this Century, probably the most acceptable equipment with this capability for the majority of general aviation aircraft—from both an operational and economic viewpoint—will involve the introduction of airborne computers for use with conventional VOR/DME receivers, coupled with suitable read-outs giving continuous position information. Aircraft so equipped also will be able to provide data link reporting of position information derived from the airborne navigation system, which will constitute an important contribution to future automation in the control of air traffic.

Rihans is a multi-phase development program initiated by the Coast Guard's Office of Research and Development. It addresses the need for an all-weather precision navigation system in harbors and their entrances. System requirements have been developed, and solutions solicited from industry. The first phase objective is a refinement analysis of the technical approach and detailed definition of the system. Contracts have been awarded for three competing concepts.

Development of a remote controlled low light level TV (LLLTV) camera-television sextant navigation system which the operator within the ship can operate to obtain celestial body altitude sightings.

The effect of the geometrical relationship between course-line and ground stations on area navigation errors is analyzed. The analysis is applied to both the RHO/THETA and the RHO/RHO systems. Graphs for determining the along-course and cross-course error standard deviations for both systems are presented. The concepts of trading off along-course precision for cross-course precision and the selection of geometrically optimal ground station configurations are discussed and illustrated. The results of this paper are of operational value since they can be used to sequence ground station selections and determine the feasibility of existing ground stations to provide area navigation for the traffic patterns of a given geographical region.

Installation and operation of satellite navigation equipment is described, including what the user should expect during a satellite pass. Characteristics of the new short Doppler computer program which promote better and more consistent accuracy are given, including documentation of 150 ft. RMS fix results. Approaches to an integrated navigation system are reviewed.

Inertial navigation systems are being adopted by air carriers for application on long-range oceanic routes and their existence in cockpits in increasing numbers warrants attention to their possible application during enroute and terminal, domestic operations. This paper discusses performance requirements for airborne area navigation systems as proposed in FAA Advisory Circular 90–45 and projects these performance requirements through 1995. The application of an INS with position updating from conventional ground referenced navigation aids to meet these present and forecasted performance requirements are assessed and the effects on pilot workload are discussed. Also included in this paper is a brief description of a planned flight evaluation to assess the effects of an integrated Inertial/DME-DME/Map Display area navigation system on aircraft navigation performance and pilot workload.

The contribution of an inertial Navigation System (INS) combined with present and projected VOR/DME to the accuracy and efficiency of area navigation is evaluated by comparing system performance with and without INS aiding. Sensitivity to INS quality is described by showing area navigation performance using high and medium accuracy production INS. The increased accuracy of the INS aided area navigation system is evaluated with respect to its impact on decreasing the protective airspace requirements, greater waypoint location flexibility, and increased accuracy of vertical navigation between waypoints. To complete the description of an inertially aided AREA-NAV system, the basic computational techniques and trade-offs for optimally mixing sensor information are presented.

Modern navigation might be dated from the invention of the marine sextant in 1734, followed by the invention of the marine chronometer in 1766. These developments made it possible to determine longitude as well as latitude at sea. The steady developments of nautical tables, almanacs, and the further refinements of sextants and timepieces gave an accuracy of position under good conditions at the turn of this century within two miles and this with a speed of solution based on four stars, of about half an hour.

Satellite navigation aid for marine craft, objectives of ATS and ATS-A, -B and -C spacecraft

This paper will discuss application of the microwave landing system as a terminal area navigation tool, as an aid to vehicle guidance, and as a position control feedback element. Navigation in this context is used to mean velocity and position determination together with a description of desired velocity and position. Guidance relates to the usage of velocity and position information to describe progress along the desired path and specifically to describe changes required to maintain that path. Control relates to manipulation of the vehicle to satisfactorily achieve the guidance commands. These aspects of the general problem of terminal area navigation using the microwave landing system as a ground based aid will be discussed from a flight control engineer's viewpoint with the emphasis on subtleties of the system characteristics that can greatly impact its eventual usefulness. Safety in flight will be discussed with respect to guidance requirements for separation, control requirements for monitoring, and integrity of the ground station itself.

General aviation is faced with the problem of traffic congestion. The present navigational methods are based on the use of VOR/DME/TACAN ground facilities resulting in routes directly to and from the ground stations. Toward relieving the problem, a logical method is the utilization of airspace or corridors removed from and essentially parallel to the VOR/DME ground facilities. These corridors would be defined and maintained relative to the VOR/DME ground structure. The method described is termed Area Navigation. Systems that satisfy the requirements of R-NAV typically navigate relative to way points within the corridor. The intent of this paper is to show why and how Doppler navigation equipment is suited to the requirements of R-NAV. The discussion points out the advantages of self-contained Doppler navigation systems such as versatility of routes, continuous velocity vector data for controlled arrival time, and accuracy with little or no need to update. A description is given of an R-NAV system comprised of a particular Doppler velocity sensor with optional navigational computer sets. The presentation of specific equipment relates real, operational hardware to the area navigation problem.

Teh C-141A is a Jet transport airplane designed primarily for use by the Military Air Transport Service for transporting cargo and troops. It will have a range in excess of 4000 nautical miles and will cruise at about 450 knots. It will have the capability of air dropping cargo and troops. The first airplane is scheduled to fly in December of this year and the airplane is expected to be operational in 1965.

The history of navigation is described briefly, with particular attention to the rapid progress that has taken place since 1940. The problems still to be solved are outlined, and possible directions of future progress in navigation are discussed. The challenge for the future is highlighted by the observation that it is significant that in one hundred and twenty years, mankind has passed the ?oats, sonic and thermal barriers,? and now is in a position to discuss openly the ultimate speed barrier of all physical matter.