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In normal geometries of siting of the ground units, the Microwave Landing System (MLS) observations in the avionics of azimuth and elevation angles plus slant range from a Distance Measuring Equipment (DME) transponder yield a unique solution for the aircraft location. However, for some unconventional geometries of the ground units in a very few, preexisting installations, these observations can be consistent with two solutions for aircraft location within the MLS coverage volume. It appears that the basic MLS concept has not dealt with this multiple solutions situation, which is possible within the present international agreements. This report shows that the MLS avionics position reconstruction algorithms, which determine the aircraft location in Cartesian coordinates and are essential in area navigation, computed centerline approach, and ground operations such as deceleration and turnoff, cannot from internal data tell which of the two solutions is true and which is false. The problem can be avoided by new constraints on the permitted sites for the MLS ground units, by restrictions on the aircraft flight paths, or by Kalman filters or equivalents in the avionics. These constraints, restrictions, and filters, are defined., Original contains color plates: All DTIC and NTIS reproductions will be in black and white.

This paper describes a user friendly Mobile Microwave Landing System (MMLS) interface design, based on menu schemes, that needs only a small number of function keys and limited display size. Although the design was developed for consideration in the local and remote control units for the MMLS, it is suitable for implementation on other control system interfaces where weight, display size, and/or the number of keys be kept to a minimum.

A series of flight tests were performed by the Federal Aviation Administration (FAA) Technical Center at the Marine Corps Air Station (MCAS) yuma, Arizona, to obtain Microwave Landing System (MLS) performance data and to compare the performance of a commissioned Category I Instrument Landing System (ILS) with the performance of a prototype MLS. The Technical Center's test bed MLS was transported to and collected with the commissioned Category I ILS on runway 21R at the MCAS Yuma. The flight data collected indicate that while both the ILS and MLS met Category I standards, the MLS represented a noticeable improvement in accuracy, signal quality, and flyability.

This study evaluated the performance of the Microwave Landing System (MLS) math model by comparing the results of the model's simulation errors along a flightpath with actual flight check measurements. The data collected for this study were designed specifically to evaluate the shadowing aircraft computations of the model. The results showed that there was some agreement between measured and modeled data, but it was concluded that further development of the shadowing aircraft computations is required.

In 1988, the Federal Aviation Administration (FAA) established the Microwave Landing System (MLS) Program Office and initiated a series of projects designed to demonstrate the operational, environmental and economic benefits of the MLS. These projects are scheduled to be completed by the end of 1991. The results of all these efforts will provide the FAA, Congress and industry with the data necessary to evaluate the future role of the MLS in the National Airspace System (NAS). The results of the first simulation conducted under the project titled 'Evaluation of Complex MLS Procedures in Multi-Airport Environments' are presented in this report. This initial experiment involved LaGuardia (LGA), John F. Kennedy (JFK), and Newark (EWR) airports in the New York Terminal Control Area.

This report examines, and determines, the accuracies required for the survey and alignment procedures in operational use of the Mobile Microwave Landing System such that the specified system accuracies will be satisfied in collocated and splite-site Category I and II system deployments. The required accuracies are within the capabilities of modern survey equipment; in fact, less sophisticated methods such as pacing, or using the known length of the monitor cables, will suffice. (Author)

Phase II flight testing of curved, segmented approaches using a Microwave Landing System (MLS) was conducted on a Twin Otter aircraft belonging to the Canadian National Research Council's Institute for Aerospace Research (IAR). Precision guidance algorithms were developed for approaches with track angle changes exceeding 180 deg. Software development flights focussed on validating these algorithms and enhancing the existing electromechanical flight director to ease the pilot workload in tracking the curved segments. A limited number of pilot evaluations confirmed that with an enhanced lateral flight director, these approaches could be flown satisfactorily regardless of the magnitude of the track angle changes. Observations were made on approach design and wind effects on curved segment tracking., Summary in English and French.

A series of flight tests were performed by the Federal Aviation Administration (FAA) Technical Center at the Miami/Tamiami Florida Airport to demonstrate the operation and capabilities of a prototype Microwave Landing System (MLS) Area Navigation System (RNAV). The Technical Center's test bed MLS was transported to and collocated with the commissioned Category I Instrument Landing System (ILS) on runway 9R at Tamiami. The flight data collected indicate that the errors in aircraft position, as computed by the MLS RNAV algorithm, consistently met Category I performance criteria, and that computed centerline and glide slope operations can be conducted with Category I accuracies to runways with lateral offsets of up to 3500 feet.

Computed centerline approaches can be divided into two subclasses: approaches to an instrument runway with an offset azimuth configuration, and approaches to a runway parallel to the primary instrumented runway. The use of lateral position computation algorithms that do not require an input elevation parameter have been proposed for situations where a full three-dimensional algorithm would be difficult in terms of memory requirements or computational power. An investigation of the impact of siting configurations on the accuracy of this type of algorithm was necessary to determine its acceptability for different categories of operation. This report presents the results of this investigation. Keywords: Microwave Landing System (MLS), Area Navigation (RNAV), International Civil Aviation Organization (ICAO), All Weather Operations Panel (AWOP).

Use of the Microwave Landing System (MLS) for area navigation and computed centerline approach requires that the MLS avionics determine the aircraft position in Cartesian coordinates relative to the runway centerline. The inputs to the avionics are the locations of the three MLS ground units and the three observations of distance, azimuth angle, and elevation angle. When the three ground units are not collocated, this process requires an iterative algorithm. A March 1988 publication of the Radio Technical Commission for Aeronautics (RTCA) presents five such algorithms. These algorithms have various problems, such as errors in the analyses and/or computer code, and divergence or false solutions, etc., within the minimum coverage area of the MLS. This report, which identifies the various problems and offers corrections, concentrates on the two algorithms that assume a conical MLS azimuth antenna, as that is likely to be the only type that will be developed. (JHD)

Position reconstruction algorithms (PRAs) based on Gaussian techniques converge very slowly, or diverge, for some geometries of ground unit and aircraft location which are within MLS system coverage. On the other hand, algorithms based on Newton-Raphson techniques usually converge very rapidly but impose a significantly greater storage requirement and computational burden on the avionics. This report presents a modified Gaussian algorithm which uses a relaxation factor to achieve rapid convergence for all geometries, and with a computational burden much less than the equivalent Newton-Raphson algorithm. It presents the theoretical foundations of this algorithm and various results showing its effects. It also compares the algorithm's storage and computational burdens against Gaussian, rotated-coordinate Gaussian, and Newton-Raphson equivalent PRAs in the MLS context.

This test plan describes a series of flight tests using Microwave Landing System (MLS) back azimuth guidance for missed approach and departure procedures. Issues to be addressed during these flight tests are: (1) The proper point in a missed approach to switch from approach azimuth to back azimuth guidance; (2) the largest MLS back azimuth offset angle usable for departures and missed approaches; and (3) the correct back azimuth full scale sensitivity. Approximately 10 industry pilots will participate as test subjects. The flights will be tracked by a radar tracker throughout each procedure. Individual and composite plots of each approach will be produced, and answers to in-flight and post-flight questionnaires will be complied. The processed data will be made available to the international aviation community to aid in the formulation of back azimuth usage guidelines. Keywords: Microwave landing systems.

The Microwave Landing System (MLS) avionics convert the received signals of range, azimuth angle, and elevation angle to yield aircraft position in Cartesian coordinates. This enables area navigation and computed centerline approaches, including multi-leg and curved approaches. When the three MLS ground units are not collocated, this requires iteration. The speed of convergence and the size of the algorithm and its computational burden affect the MLS avionics storage and timing requirements. Gaussian algorithms tend to be relatively compact but diverge at azimuth angles within the coverage of the MLS, while Newton-Raphson algorithms require more storage and impose a greater computational burden. This report presents a Gaussian algorithm which, by rotating the coordinate system, enables fast convergence everywhere within the MLS coverage, and with a computational burden significantly less than an equivalent Newton-raphson algorithm. Keywords: Computed centerline approach, Gauss-Seidel, Microwave landing system (MLS), Position reconstruction algorithm, Rotated Gauss-Seidel.

The field of modern guidance and control systems has been raised to a very high level of capability because of the powerful high technology advances of the past several decades. This NATO AGARDograph captures the spirit of these powerful capabilities, and it is structured in 8 parts: These include: Integrated guidance and control systems; NAVSTAR/GPS Systems; Optical gyroscope and control systems; Integrated communication and navigation systems; Integrated navigation flight control systems; Civil aircraft navigation and traffic control; and Land navigation systems., Original contains color plates: All DTIC and NTIS reproductions will be in black and white.

A series of flight evaluations were conducted at Cardiff and Heathrow Airports in the United Kingdom. The flight evaluation were jointly conducted by the Kingdom of the Netherlands, the Civil Aviation Authority (CAA) of the United Kingdom, and the Federal Aviation Administration (FAA) of the United States of America. The flight evaluations were undertaken to validate recommendations made at the 13th All Weather Operations Panel (AWOP) Meeting of the International Civil Aviation Organization (ICAO). The recommendations addressed permissible Microwave Landing System (MLS) azimuth antenna offsets from the primary runway, by permissible parallel secondary runway locations, and the use of standard distance measuring equipment for computed centerline operations. In all cases, flight data validated the recommendations. Additionally, subject pilots expressed strong support for the advanced procedures they flew. Although not an objective of the evaluation, interoperability of MLS equipment manufactured in five different countries was demonstrated.

The report describes adaptation of a computer based simulation of a transport aircraft automatic landing system to enable study of microwave landing system (MLS) flare guidance. The simulation was used to examine the allowable errors from the range and elevation angle measuring sub-systems of the MLS flare system.

These Proceedings consist of the papers and discussions presented at the Avionics Panel Meeting on Modeling and Simulation held in Paris, France, October 1979. Papers were divided as follows: 6-Tutorial, 8-C3 System Simulation, 5-Airborne Surveillance System Simulation, 5-Manned Flight Simulators, 4-Identification, Communication Navigation, and Countermeasure Simulation, and 11 on Avionics System Simulation., Presented at a Meeting of the Avionics Panel held in Paris, France, 15-19 Oct 1979.

This report provides guidance in the selection of locations on an airport for installation of MLS antennas. A description of the operation of the Microwave Landing System (MLS) is given and the preferred locations for MLS antennas are described. A discussion of possible interference effects due to reflecting and shadowing objects is presented. Techniques for determining potential interference sources are given.

The Microwave Landing System (MLS) program is designed to meet both civil and military operational needs. It will eventually replace the Instrument Landing System (ILS). After a system/equipment development phase, the Federal Aviation Administration, in 1979 began a Service Test and Evaluation Program (STEP) to obtain experience for developing criteria for siting, installation and preliminary operational procedures. Feasibility demo ground equipment from the development phase was used and user aircraft were equipped with MLS receivers. This report contains engineering evaluation of the FAA Technical Center flight test data taken on the Texas Instruments' manufactured Small Community MLS, as installed for STEP at Philadelphia International Airport Runway 17. The equipment performance was found to generally meet the FAA-STD-022b Path Following Error and Control Motion Noise requirement, but not the linearity requirement. Apparent aircraft propeller induced noise effects were identified.

This report describes test procedures and results of series of tests designed to identify microwave landing system (MLS) heliport flight inspection procedures. The tests, conducted in November 1985, demonstrated the feasibility of using helicopter to perform some portion of the flight inspection of the MLS at heliports. Significant findings included the fact that radio theodolite techniques could be used for tracking a helicopter not equipped with stability augmentation equipment. Constituent parts of portable flight inspection package were also identified and tested.

During the late fall of 1985 and the winter of 1986 test flights were conducted at the Federal Aviation Administration (FAA) Technical Center's Heliport at Atlantic City International Airport, N.J. The purpose of these flights was to verify signal coverage of the Microwave Landing System (MLS) collocated at the heliport. Other activities included the measurement of the signal characteristics of the Hazeltine Model 2400 MLS which was installed at the heliport. Elevation and azimuth course widths were determined and, using classical Z transform techniques, statistical estimates of control motion noise and path following error were obtained. These estimates were compared with the FAA Standard for Interoperability and Performance Requirements of MLS. Results obtained were excellent. Tolerance limits were consistently met. The data revealed that wide beam width antenna systems when installed at heliports can meet specification tolerances contained in the FAA specification for MLS Interoperability and Performance Requirements.

This report describes the trend analysis evaluation of the Sikorsky S-76A missed approach profiles following precision microwave landing system (MLS) approaches at glidepath angles of 3 deg, 6 deg, and 7.5 deg at a minimum instrument meteorology conditions airspeed (V sub mini) of 40 knots indicated airspeed (KIAS). It describes the flight test facilities, methodology, and addresses topics such as how flight test data are collected and what is done with it. It also describes each of the helicopter procedures flown during the project and provides an analysis of the pilots subjective opinions concerning the acceptability and workload associated with these procedures. It was concluded that the trend indicates that no current terminal instrument procedures (TERPS) criteria would be violated by reducing V sub mini to 40 KIAS. The plots indicated that there wer no penetrations of the 20:1 surface missed approach surface. The maximum deviation allowed by TERPS for the height loss at missed approach rises along a 20:1 plane which begins at the surface or 250 feet below surface began at ground level. At most, only a 40-foot fly under at decision height (DH) was noticed during the 24 missed approaches flown. However, this information should be considered indicative rather than conclusive due to the small sample size (24 approaches). Additional testing would be required to provide TERPS quality data.

This report deals with current and planned aircraft guidance systems as they apply to Army tactical precision landings in the combat environment. Self-contained avionics systems and less sophisticated systems have been evaluated. Ground guidance is defined as a means to safely, efficiently, and rapidly aid in the movement of aircraft from their transition point of landing to a final destination. The study addressed the following four tasks: 1) Review Army Requirements (Ground Guidance) by research of current documentation and by extensive interviews. 2) Identify alternative systems through specifications and discussions with government and industrial personnel. 3) Evaluate systems by conducting aviator and engineer evaluations. and 4) Identify and document best approach for Army use in the tactical environment., See also AD-A167 780.

In order to take full advantage of the helicopter's unique flight characteristics, enhanced terminal instrument procedures (TERPS) need to be developed for a variety of non-standard operational situations. These include non-standard landing navigation aids, precision and non-precision approach profiles, landing sites, and avionics systems. Currently, TERPS criteria are largely established by extensive flight testing. This study examined the requirements for using helicopter cockpit simulators in place of flight testing to generate data necessary for enhanced TERPS development.

Under today's rules independent parallel approaches are restricted to runways separated by at least 4300 feet. Currently the FAA is investigating a proposal to achieve reductions down to 3000 feet with the use of an improved surveillance system (1 milliradian accuracy/1 second update). This paper proposes new procedures to achieve such reduction, using existing radars, by executing 'almost-parallel' MLS or ILS approaches. Almost-parallel approaches include curved paths where very shallow rates of turn are required and offset straight paths where the angle of offset with respect to the extended runway centerline is less than 3 degrees. Some issues of concern that arise, such as blunder resolution and pilot's loss of sight of other approach course during curved approaches, are discussed in this paper. Alternatives for an early implementation and site-specific sample applications are presented. The objective of this paper is to present in a concise manner this preliminary concept that has already generated some interest as a solution to reduced parallel operations. As with any new concept, analysis by all concerned parties have to be performed followed by simulations and/or demonstrations before the concept can be considered implementable. (Author)

This is the final technical note for the 'Hardware Performance Analysis of the Basic Narrow Microwave Landing System (MLS) at Washington National Airport (DCA) in the Service Test and Evaluation Program (STEP)' for the period January 1,1981 through June 30, 1983. The MLS configuration, limits of signal operation, system and subsystem operation, data collection and analysis are described. Equipment and environmental problem areas uncovered during the test and evaluation are discussed in the Results section of this report. Chargeable failures are identified and listed and engineering investigations are discussed. Remote Maintenance Monitoring System (RMMS) data analysis are presented. Conclusions and recommendations are listed. Keywords include: Microwave Landing System (MLS), Service Test and Evaluation Program (STEP), MLS Hardware Performance Analysis, and MLS Basic Narrow System.

Advanced technology in military aviation is developing rapidly. The Global Positioning System (GPS) and Microwave Landing System (MLS) will give the pilot precision navigation capability when fully deployed in the 1990s. The Joint Tactical Information Distribution System (JTIDS) will give the pilot the capability to display enemy and friendly aircraft in his area in his cockpit. At the same time, our mobile air traffic control (ATC) radars are aging and need to be replaced. But, with the new technology in the cockpit, it may be more feasible to eliminate ground-based ATC radar and let the pilot do his own ATC from the cockpit. This study examines the feasibility of a cockpit-based ATC system by looking at the requirement for military ATC, specific capabilities that new technologies give the pilot, and human considerations in a cockpit-based ATC system. The study concludes that a cockpit-based ATC system is not feasible and that there will be a need for ground-based ATC radar, at least through the year 2000. (Author)

Contents: Structural Loading Criteria; Summary of Minimum Margins of Safety; Analysis; Unoccupied Areas; Receiver Installation Models C-130E/H, WC- 130E/H, HC-130H/N/P; Data Bus Coupler/Signal Splitter Installation Models C- 130E/H, WC-130E/H, HC-130H/N/P; Receiver/Data Bus Coupler Installation Model C- 130B; Signal Splitter/Relay Panel Installation Model C-130B; Front Antenna Installation; AFT Antenna Installation; AFT Antenna Installation; AFT Pressure Feed-Thru; Crew Occupied Areas; Top Antenna Installation; Relay Panel Installation; Relay Panel - Models C-130E/H/B; Relay Panel - Models C-130H (late); Relay Panel - Models HC-130H/N/P, WC-130E/H; Forward Pressure Feed-Thru.

Contents: Power Loading Data; Power Loading for the Microwave Landing System (MLS); AC Power Loading for MLS Equipment; DC Power Loading for MLS equipment; AC Electrical Power; DC Electrical Power; AC Load; DC Load., Prepared in cooperation with Smiths Industries, Grand Rapids, MI.