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A forward scattermeter, consisting of transmitter and receiver heads mounted on a fork, is used in the New Generation Runway Visual Range (NGRVR) System to assess the clarity of the atmosphere. The scatter meter is calibrated by comparison with reference transmissometers. The consistency of the calibration from one unit to the next is verified by measuring the fork geometry and using a performance model to predict the expected calibration variation for different forks. The model also assesses the possible effects of head variations. The variations in fork geometry through the 650-unit production run are presented. The additional steps needed to complete the calibration validation are defined., Prepared in collaboration with Scientific and Engineering Solutions, Inc., Orleans, MA.

Ratios of slant visual range measured from heights of 100, 124, and 155 feet to horizontal visual range measured at 15 feet were computed for low- visibility regimes. These ratios were found to be related to the linear fog density profile expressed as the difference in horizontal atmospheric transmittance between the top (100-, 124-, and 155-foot) and bottom (15-foot) levels. It was determined that useful estimates of slant visual range could be provided through these relationships. The predictions would be most accurate when the visibility decreased with height (most common fog structure). A slight increase in accuracy would also be expected with decreasing slant height., Continuation of Rept. No. FAA-RD-77-34, ADA041134.

A microprocessor-based automated airfield weather observing and forecasting system called MAWS (Modular Automated Weather System) was developed to demonstrate the feasibility of modernizing many of the observing and forecasting functions performed in operational base weather stations. Scott Air Force Base, Illinois, was chosen as the demonstration site and operations were conducted from January 1977 through January 1979. Weather sensors at five observation sites around the airfields were polled several times each minute, the data transmitted over commercial, voice-grade telephone lines to a central supervisory microprocessor where the data were suitably collated, averaged and formatted for display on alpha-numeric display devices at key locations and for magnetic tape archiving for post analysis. The demonstration confirmed that modernized weather support can be largely achieved with state-of-the-art, commercially available hardware/software. Such a system would be compatible with other automation efforts in civilian weather services and other C-cubed efforts in the DOD. The advantage of spatially and temporally detailed weather information in marginal and adverse situations was documented. Sensor siting considerations were addressed in relation to specific weather elements and observational requirements. The contributions of automated met watch procedures and short-range guidance forecasts of RVR landing minima were demonstrated. Feedback on system performance and acceptability was obtained from cognizant AWS offices.

This report briefly describes the evolution of the FAA/NBS Runway Visual Range RVR transmissometer system into a breadboard Airport Visibility Measuring System (ARVIS) which has been laboratory tested and which will undergo field tests at the National Aviation Facilities Experimental Center (NAFEC) in Atlantic City, NJ during 1975. Appendix I of this report documents in detail the development of a Signal Data Converter Unit (SDCU) as a replacement for the SDCU used in the FAA/NBS RVR system. Appendix II describes an analog computer for calculating RVR., Prepared in cooperation with Charles Stark Draper Lab., Inc., Cambridge, MA. See also Rept. no. TSC-FAA-72-1, AD-744 873.

Runway visual range (RVR) is an aviation visibility value obtained by utilizing a special purpose signal data converter. Atmospheric transmittance, one of the processing parameters used, is provided by a National Bureau of Standards type transmissometer that samples clarity of the atmosphere by measuring the amount of incandescent light from a known source remaining in the beam after passing through a baseline distance of 500 or 250 feet. New types of visibility sensors are now being produced that operate on a light-scattering principle rather than attenuation. These new types of sensors are being considered as alternatives to the NBS transmissometer. If found suitable, these new sensors will require signal conditioning circuitry in order to operate in conjunction with existing, standard-type RVR computers. This report describes the design and testing of such an interface circuit to permit use of the EG and G model 207 Forward Scatter Meter (FSM) with the RVR computer. It was concluded that the circuit design does provide accurate interface between the EG and G model 207 FSM and FA-7871-type signal data converters.

The runway visual range (RVR) for a Type L-850 bidirectional centerline runway light has been calculated for the red and white output ports at three different current settings for both day and night illuminance thresholds. The calculations are based on certain parameters measured in our laboratory on a sample light. The resulting RVRs are compared to the standard RVRs based on the High Intensity Runway light (HIRL). An analysis is also included on the error introduced by ignoring the spectral transmittance of the atmosphere. (Author)

Values of Runway Visual Range (RVR) were developed for various atmospheric transmittances utilizing Allard's Law and Koschmieder's Law. Commonly employed constant's of pilot's contrast threshold and visual illuminance threshold are utilized in the appropriate RVR equations. Computations are based on a 250 foot baseline transmissometer with light target intensities of 10,000, 2,000 and 400 candela, values which are presently used in the United States. Information is presented in tabular form showing transmittances corresponding to runway visual range readings from 600 feet to 7000 feet in 50 foot increments. Each table includes data for each of the three light target intensities. A total of eight tables is provided. The computer program which was utilized to develop each set of data is included with each table.

A test program was conducted to evaluate multi-transmissometer systems. These consisted primarily of instruments at touchdown, midpoint, and roll-out locations on a runway at five airfields distributed across the U. S. continent in differing climatic regimes. The airfields were located at Atlantic City, N. J., New York, N. Y., Chicago, Ill., Denver, Colo., and Los Angeles, Calif. The data acquisition program is discussed as is the analyses of data. Primary objective of the program was to determine if a need exists for three transmissometer systems per runway under a variety of weather categories. (Author)

A test program was developed and implemented to evaluate multi-transmissometer systems. These consist primarily of instruments at touchdown, mid-point, and rollout locations at five airfields distributed across the continent in differing climatic regimes. The airfields are located at Atlantic City, N. J., New York City, N. Y., Chicago, Ill., Denver, Colo., and Los Angeles, Calif. The data acquisition technique and program are described. Further data processing is scheduled. Partial analysis of available data indicates that no single transmissometer will always be most representative of lowest visibility conditions at any airport and even with three systems along the runway unreported variations in RVR will still occur. Analysis of 55-, 45-, and 15-second sampling intervals for RVR computation shows little difference between 55- and 45-second sampling. The number and magnitude of differences increase when RVR from a 15-second sampling is compared to RVR from a 55-second sampling especially during rapid changes in transmittance. (Author)

The results of a controlled observational program were used to validate the credibility of the current runway visual range system, and to provide a basis whereby future visual range systems and lighting methods can be compared. It was found that the current runway visual range system concept is generally credible although certain areas were noted to be considered for modification. Runway visual range for day is conservative in that most static observers could see farther than the current system predicts. The static observer's visual range of runway lights by day does not conform to Allard's Law when the visual illuminance threshold value is fixed. Night runway visual range, as predicted by the current system, approximates the average visual range of the static observations and generally conforms to Allard's Law. The fact was established that runway visual range represents a probability of sighting light targets, and as such should be recognized by the user as not being an exact absolute value. A benchmark system is proposed whereby other visual range systems and lighting techniques can be compared.

Tato bakalářská práce se zabývá dohledností a dráhovou dohledností, jejich hlášením v různých meteorologických zprávách, způsoby jejich určování a jevy, které je zhoršují. Soustřeďuje se na mlhy jako hlavní příčinu malé dohlednosti a zabývá se jejich vznikem, rozdělením a jejich vlivem na letecký provoz. Zvláštní pozornost je věnována způsobům určování dohlednosti a dráhové dohlednosti na letišti Brno-Tuřany a výskytu mlh na tomto letišti. Obsahuje výsledky statistického zpracování mlh při směru a rychlosti větru a jejich synoptických podmínkách, a to během chladného pololetí 2008/09 až 2012/13., This thesis deals with visibility and runway visual range, their messages in different meteorological reports, the methods of determining and phenomena, which worsen them. It focuses on fogs as the main cause of low visibility and discusses their origin, division and their impact on air traffic. Particular attention is paid to ways of determining visibility and runway visual range at the airport Brno-Tuřany and fogs at this airport. This thesis contains the results of statistical processing of fog in wind speed and direction and synoptic conditions, during the cold term of 2008/09 to 2012/13.

Tato bakalářská práce se zabývá dohledností a dráhovou dohledností, jejich hlášením v různých meteorologických zprávách, způsoby jejich určování a jevy, které je zhoršují. Soustřeďuje se na mlhy jako hlavní příčinu malé dohlednosti a zabývá se jejich vznikem, rozdělením a jejich vlivem na letecký provoz. Zvláštní pozornost je věnována způsobům určování dohlednosti a dráhové dohlednosti na letišti Brno-Tuřany a výskytu mlh na tomto letišti. Obsahuje výsledky statistického zpracování mlh při směru a rychlosti větru a jejich synoptických podmínkách, a to během chladného pololetí 2008/09 až 2012/13., This thesis deals with visibility and runway visual range, their messages in different meteorological reports, the methods of determining and phenomena, which worsen them. It focuses on fogs as the main cause of low visibility and discusses their origin, division and their impact on air traffic. Particular attention is paid to ways of determining visibility and runway visual range at the airport Brno-Tuřany and fogs at this airport. This thesis contains the results of statistical processing of fog in wind speed and direction and synoptic conditions, during the cold term of 2008/09 to 2012/13.

Tato bakalářská práce se zabývá dohledností a dráhovou dohledností, jejich hlášením v různých meteorologických zprávách, způsoby jejich určování a jevy, které je zhoršují. Soustřeďuje se na mlhy jako hlavní příčinu malé dohlednosti a zabývá se jejich vznikem, rozdělením a jejich vlivem na letecký provoz. Zvláštní pozornost je věnována způsobům určování dohlednosti a dráhové dohlednosti na letišti Brno-Tuřany a výskytu mlh na tomto letišti. Obsahuje výsledky statistického zpracování mlh při směru a rychlosti větru a jejich synoptických podmínkách, a to během chladného pololetí 2008/09 až 2012/13., This thesis deals with visibility and runway visual range, their messages in different meteorological reports, the methods of determining and phenomena, which worsen them. It focuses on fogs as the main cause of low visibility and discusses their origin, division and their impact on air traffic. Particular attention is paid to ways of determining visibility and runway visual range at the airport Brno-Tuřany and fogs at this airport. This thesis contains the results of statistical processing of fog in wind speed and direction and synoptic conditions, during the cold term of 2008/09 to 2012/13.

Tato bakalářská práce se zabývá dohledností a dráhovou dohledností, jejich hlášením v různých meteorologických zprávách, způsoby jejich určování a jevy, které je zhoršují. Soustřeďuje se na mlhy jako hlavní příčinu malé dohlednosti a zabývá se jejich vznikem, rozdělením a jejich vlivem na letecký provoz. Zvláštní pozornost je věnována způsobům určování dohlednosti a dráhové dohlednosti na letišti Brno-Tuřany a výskytu mlh na tomto letišti. Obsahuje výsledky statistického zpracování mlh při směru a rychlosti větru a jejich synoptických podmínkách, a to během chladného pololetí 2008/09 až 2012/13., This thesis deals with visibility and runway visual range, their messages in different meteorological reports, the methods of determining and phenomena, which worsen them. It focuses on fogs as the main cause of low visibility and discusses their origin, division and their impact on air traffic. Particular attention is paid to ways of determining visibility and runway visual range at the airport Brno-Tuřany and fogs at this airport. This thesis contains the results of statistical processing of fog in wind speed and direction and synoptic conditions, during the cold term of 2008/09 to 2012/13.

FA795/A7090, The forward scattermeter has many practical advantages over the transmissometer (single mounting pole, greater dynamic range, etc.). However, before a forward scattermeter could be accepted for an RVR system, a number of criteria had to be satisfied: 1) the calibration must be accurate and consistent (a) from one unit to the next and (b) for all important obstruction to vision (fog and snow for RVR); 2) the windows of the sensors must not clog in blowing snow; and 3) scatter measurements in a small volume of space must represent conditions over the runway as well as measurements made by a transmissometer which averages over a baseline (250 feet (76.2 m) at US airports). Many different scattermeter designs were tested extensively, both in the field and in climatic chambers, before all acceptance criteria could be satisfied. The report describes the evolution of scattermeter design and presents the test methodology and results for the new RVR system.

The objective of this study has been to perform an economic comparison by conducting a cost-benefit analsyis (CBA) of the five Local Area Augementation System (LAAS) and alternative architectures. The five architectures chosen by the FAA for the study are: Pseudolite kinematic LAAS, Wide-Lane Kinematic LAAS, Code-Based LAAS, Instrucment Landing System (ILS), and the LAAS-Glide Slope System. A comparison of archhitecture based on the benefit/cost (B/C) ratio and cost-effectiveness criterion indicates that the Code-based LAAS architecture has, by far,the highest B/C ratio of 4.0 and the lowest life-cycle cost of $860.9 million over a 15 year time horizon. The B/C ratios of other non-ILS architectures are in the range of 3.4 to 3.7, and the life cycle costs in the range of $946.5 milliono to $1,014.6 million. For the reference ILS architecture, the study estimates a low B/C ratio of 0.4 and the life cycle cost of $921.2 million. The latter cost is not much different from other architecture life cycle, despite the exclusion of the substantial sunk cost of existing runway ILS and aircraft avionics equipment.

DOT-TSC-765, Introduction, Objective, Operational FAA visibility information, Proposed additional visibility information, Visibility measuring systems deployment analysis and schedules, Commercially available visibility measuring equipment, Airport visibility system (ARVIS), Elements of deployment cost for typical RVR systems commercially available, Elements of deployment cost for proposed Arvis installation, Elements of deployment cost for FAA proposed SVR system, Typical visibility measuring system upgrade deployment costs, Summary and conclusions, Appendices, This report analyzes the deployment cost for different visibility measuring systems necessary to satisfy CAT I, II, and II operations. The analysis is based on airport operational requirements and data for commercially available visibility measuring equipment. Estimated deployment schedules of visibility measuring equipment for the FY76-FY85 period are developed. Visibility equipment requirements for each runway category are identified. Eight (8) selected airports are analyzed for their existing visibility equipment, future plans and estimated requirements. Cost comparisons of various alternatives are performed for typical visibility measuring systems. Commercially available visibility measuring equipment relevant to airport operations are listed and described. Specification and performance characteristics as well as cost factors are considered. The deployment cost for the SVR system which may become operational in the next few years is investigated. The deployment cost for the airport visibility system (ARVIS) developed by TSC as wlel as modifications kits for the FAA/NBS transmissometer system are analyzed.

Summary, Conclusions, Recommendations, Background, Test description, Test results, Epilogue, Appendices, Three transmissometers and five forward-scatter meters were evaluated for measuring fog, haze, rain and snow in the large test chamber of the Eglin Air Force Base Climatic Laboratory. Methods were developed for generating moderately uniform and stable fog and haze conditions. Fog densities equivalent to Runway Visual Range (RVR) values of 100 to 600 feet were achieved; such fog densities are rare in nature and were primary reason for undertaking the chamber tests. No unusual characteristics of the chamber fogs were noted. Laser transmissometers with 40- and 250- foot baselines served as standard sensors for the tests. Because of inhomogeneities in the chamber, only the 40-foot baseline gave good correlations with most of the test sensors. Consequently, one of the forward-scatter meters, the EG&G 201, was used as a secondary standard for high visibility (RVR above 1000 feet) conditions. With appropriate corrections, all the test sensors met the 15 percent root-mean-square error pass-fail criteria for measuring dense fog.

R1043, This is the final report #1 of the Visibility Measuring Devices project, PPA-FA-15-Q, carried out for the Federal Aviation Administration at the Transportation Systems Center, both under the Department of Transportation. The report reviews present techniques for measuring, atmospheric transmittance and its conversion to runway visual range. The response of the pilot to visual cues used in determining the visibility is discussed as a function of his cockpit environment. The lights, utilized by the FAA as targets for visibility determinations are, discussed and used in the computations. New techniques for visibility measurements and new, concepts and definitions are discussed and analyzed. The emphasis is on techniques for measuring slant visual range by means of optical remote sensing devices. Various problems, relating to atmospheric modeling.

A095/AOF090, A forward scattermeter, consisting of transmitter and receiver heads mounted on a fork, is used in the New Genreration Runway Visual Range (NGRVR) System to assess the clarity of the atmosphere. The scattermeter is calibrated by comparison with reference transmissometers. The consistency of the calibration from one unit to the next is verified by measuring the fork geometry and using a performance model to predict the expected calibration variation for different forks. The model also assesses the possible effects of head variations. The variations in fork geometry through the 650-unit production run are presented. The additional steps needed to complete the calibration validation are defined.

The bibliographical survey provides reference information and background material to assist in the selection of principles and measuring techniques which may be used in the development of future systems to measure Runway Visual Range (RVR), Slant Visual Range (SVR), Approach Light Contact High (ALCH), Taxi Visual Range (TVR), or any other parameter to be defined which will describe the photometric conditions of runways and/or taxiways under actual operational and atmospheric visibility conditions. This survey gives much of the literature which has been published on the subject of visibility, the factors inherent to the target background, atmospheric optics, visibility-measuring instrumentation, photometric properties of the eye, visibility data-processing, landing takeoff and taxiing problems which are imposed by reduced visibility.

The runway visual range (RVR) for a Type L-850 bidirectional centerline runway light has been calculated for the red and white output ports at three different current settings for both day and night illuminance thresholds. The calculations are based on certain parameters measured in our laboratory on a sample light. The resulting RVRs are compared to the standard RVRs based on the High Intensity Runway light (HIRL). An analysis is also included on the error introduced by ignoring the spectral transmittance of the atmosphere. (Author)

Tato bakalářská práce se zabývá dohledností a dráhovou dohledností, jejich hlášením v různých meteorologických zprávách, způsoby jejich určování a jevy, které je zhoršují. Soustřeďuje se na mlhy jako hlavní příčinu malé dohlednosti a zabývá se jejich vznikem, rozdělením a jejich vlivem na letecký provoz. Zvláštní pozornost je věnována způsobům určování dohlednosti a dráhové dohlednosti na letišti Brno-Tuřany a výskytu mlh na tomto letišti. Obsahuje výsledky statistického zpracování mlh při směru a rychlosti větru a jejich synoptických podmínkách, a to během chladného pololetí 2008/09 až 2012/13., This thesis deals with visibility and runway visual range, their messages in different meteorological reports, the methods of determining and phenomena, which worsen them. It focuses on fogs as the main cause of low visibility and discusses their origin, division and their impact on air traffic. Particular attention is paid to ways of determining visibility and runway visual range at the airport Brno-Tuřany and fogs at this airport. This thesis contains the results of statistical processing of fog in wind speed and direction and synoptic conditions, during the cold term of 2008/09 to 2012/13.