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This work presents an analysis of low-visibility event persistence and prediction at Villanubla Airport (Valladolid, Spain), considering Runway Visual Range (RVR) time series in winter. The analysis covers long- and short-term persistence and prediction of the series, with different approaches. In the case of long-term analysis, a Detrended Fluctuation Analysis (DFA) approach is applied in order to estimate large-scale RVR time series similarities. The short-term persistence analysis of low-visibility events is evaluated by means of a Markov chain analysis of the binary time series associated with low-visibility events. We finally discuss an hourly short-term prediction of low-visibility events, using different approaches, some of them coming from the persistence analysis through Markov chain models, and others based on Machine Learning (ML) techniques. We show that a Mixture of Experts approach involving persistence-based methods and Machine Learning techniques provides the best results in this prediction problem.

We address the prediction of low-visibility events at airports using machine-learning regression. The proposed model successfully forecasts low-visibility events in terms of the runway visual range at the airport, with the use of support-vector regression, neural networks (multi-layer perceptrons and extreme-learning machines) and Gaussian-process algorithms. We assess the performance of these algorithms based on real data collected at the Valladolid airport, Spain. We also propose a study of the atmospheric variables measured at a nearby tower related to low-visibility atmospheric conditions, since they are considered as the inputs of the different regressors. A pre-processing procedure of these input variables with wavelet transforms is also described. The results show that the proposed machine-learning algorithms are able to predict low-visibility events well. The Gaussian process is the best algorithm among those analyzed, obtaining over 98% of the correct classification rate in low-visibility events when the runway visual range is $${>}$$ 1000 m, and about 80% under this threshold. The performance of all the machine-learning algorithms tested is clearly affected in extreme low-visibility conditions ( $${

The main methods for determining the length of the runway at the landing stage are shown in the given article. The shortcomings of these methods are proved. Statistical data that shows the need of landing distance recalculation for calculation of the required length of the runway are provided. The advanced mathematical model for calculating the required length of the runway at the landing stage is shown.

Two studies (Boeing 777 and 737 simulators) examined flight crews’ use of an Enhanced Flight Vision System (EFVS) for taxiing in low-visibility conditions in lieu of infrastructure for Low-Visibility Operations/Surface Movement Guidance and Control Systems (LVO/SMGCS). Twenty-five flight crews completed 21 short taxi scenarios under combinations of the following variables and levels: Runway visual range (RVR; 300, 500, 1000 ft); Enhanced-Flight-Vision System in head-up display (on/off); airport infrastructure - 3 levels. Two scenarios dealt with detecting obstacles near the taxi path. In both studies, the use of EFVS resulted in fewer route deviations, the majority of which occurred at 300 feet RVR with edge lights and either a standard painted centerline (Level 1) or a painted centerline with LVO/SMGCS “enhancements” but without centerline lights (Level 2). Deviation from taxiway centerline was variable, but was consistent between display conditions (EFVS/no EFVS) (mean

With special geographical and meteorological conditions, it is difficult for planes to fly at High altitude airport. Thus the rate of delay and accident remains very high. Flight accidents mostly happened when the planes was taking off or land. These are directly related with the runway visual range, which is crucial to airport operation. This paper propose a method to obtain the meteorological feature by using the deep auto-encoding network. Guided by this method, we use the auto-encoding network to study the meteorological feature and the Deep auto-coding network to explore the potential information in 2 dimensional data. We have made a real-time prediction of the runway visual range, by using the algorithm of machine learning and deep learning and the monitoring of meteorological characteristic through different dimensions. The precision rate is 91% and the TS score is up to 81.14%, 6% higher than the industry level of 75%. The method based on Ensemble Learnings multiple model fusion was studied to improve the overall performance. The final overall TS score of the fusion model have reached 82%. The study of the runway visual range prediction method in this paper help space dispatcher make a comprehensively and efficiently predict of runway visual range. It is expected to improve airport operation and reduce economic losses caused by flight accident efficiently.

At towered airports, air traffic controllers use an “out-the-window” view for situation awareness of the entire airport environment and for ensuring safe operation on and around airport runways. A controller's view of the runways can be limited by a number of factors, including weather conditions, obstructions, and night operations, making some aircraft movements difficult to detect especially in the absence of surface surveillance systems. In remote tower concepts, the same factors can impact the controller's airport view via cameras. While surface surveillance systems, when available, are designed to supplement the controller's visual surveillance, existing systems do not provide sufficient precision to identify the location of the aircraft nose or tail relative to runway entry and exit points, as designated by hold lines. These limitations can negatively impact the controller's situation awareness and can cause controllers to clear aircraft onto the runway when the runway is occupied, resulting in an operational error. The MITRE Corporation's Center for Advanced Aviation Systems Development (MITRE) conceived of, developed, and tested an airport runway hold line surveillance (HLS) capability that automatically monitors safety critical runway hold lines for aircraft crossings. The capability is envisioned to provide additional surveillance that improves safety but can also positively impact airport efficiency and runway capacity as controllers will no longer have to wait for aircrews to indicate that they are clear of the runway via radio before clearing the next operational use of the runway MITRE CAASD evaluated short-range surveillance sensor technologies and selected a commercially-available automotive radar sensor, then developed and tested a proof-of-concept prototype of the HLS concept. MITRE set up the HLS prototype at Washington Dulles International Airport (IAD) for data collection and analyzed the system's performance. The results of the analysis, measured in terms of positional accuracy, indicate that the concept of detecting aircraft position relative to the hold line using this type of sensor and automation is feasible and could enhance safety in both remote tower and conventional tower environments.

This paper describes operational concepts, certification considerations, and initial user evaluations for using an avionics system for low visibility taxi operations. The ability to taxi to/from the runway safely and efficiently in low visibility conditions is becoming increasingly important as airplanes and aircrews become equipped and approved for low visibility landing and takeoff. Typically in the United States, any surface operations below 1200 ft. Runway Visual Range (RVR) generally encourage the airport authority to have an approved Low Visibility Operations / Surface Movement Guidance and Control System (LVO/SMGCS) plan which specifies certain markings, signs, lighting, and controls in the airport movement area. Operations below 600 ft. RVR, or 500 ft. RVR under U.S. Federal Aviation Administration (FAA) Order 8000.94 enablement, require additional infrastructure in movement and non-movement areas and may also require Airport Surface Detection Equipment (ASDE or ASDE-X) or a suitable substitute1 to allow the ground controllers to adequately monitor surface traffic. Surface operations below 300 ft. RVR are generally precluded (or need extra controls such as the use of a “follow-me” truck). The operational concepts described in this paper show how using on-board systems based on synthetic and enhanced vision systems may substitute for or augment an airport’s existing infrastructure. These on-board systems along with proper additional mitigations under the LVO/SMGCS concept of Protected Low Visibility Taxi Routes (PLOVTR) would enable an appropriately equipped aircraft and qualified crew to safely taxi in low visibility conditions.

We consider the problem of emission of sound by an airplane in the stage of its take-off run along the runway of an airdrome under the conditions of wind action. The aircraft engines play the role of the sources of sound. In the problem, they are modeled by point sources moving in air with a constant acceleration parallel to the plane interface between the acoustic and solid elastic half spaces. The solution of the problem is obtained by using the Fourier integral transformation with respect to time and space coordinates and the method of stationary phase. We also perform the numerical analysis of the spacetime distributions of sound pressure and the levels of sound pressure for the case of take-off of a sixengine An-225 “Mriya” aircraft.

In this study, we surveyed the operating status of the Runway for the Light Sport Aircraft(LSA) in Korea, and analyzed the Airfield Facilities Manual for the Air Leisure and the Standard Specification for Recreational Airpark Design. Based on the information, we presented the displacement of the threshold concept, to ensure the Runway Length and the Runway Safety Area, and operation of LSA in Korea.

Synthetic Vision (SV) and Enhanced Flight Vision Systems (EFVS) may serve as game-changing technologies to meet the challenges of the Next Generation Air Transportation System and the envisioned Equivalent Visual Operations (EVO) concept - that is, the ability to achieve the safety and operational tempos of current-day Visual Flight Rules operations irrespective of the weather and visibility conditions. One significant obstacle lies in the definition of required equipage on the aircraft and on the airport to enable the EVO concept objective. A motion-base simulator experiment was conducted to evaluate the operational feasibility and pilot workload of conducting departures and approaches on runways without centerline lighting in visibility as low as 300 feet runway visual range (RVR) by use of onboard vision system technologies on a Head-Up Display (HUD) without need or reliance on natural vision. Twelve crews evaluated two methods of combining dual sensor (millimeter wave radar and forward looking infrared) EFVS imagery on pilot-flying and pilot-monitoring HUDs. In addition, the impact of adding SV to the dual sensor EFVS imagery on crew flight performance and workload was assessed. Using EFVS concepts during 300 RVR terminal operations on runways without centerline lighting appears feasible as all EFVS concepts had equivalent (or better) departure performance and landing rollout performance, without any workload penalty, than those flown with a conventional HUD to runways having centerline lighting. Adding SV imagery to EFVS concepts provided situation awareness improvements but no discernible improvements in flight path maintenance.

A parameterization of runway visual range (RVR) has been developed using relevant meteorological parameters such as visibility (Vk), relative humidity (RH), temperature (T), precipitation intensity (PI), and precipitation type (PT) measured in years between 2009 and 2011 at Toronto Pearson International Airport during the Canadian Airport Nowcasting Project. The FD12P probe measured PI, Vk, and PT. The observed Vk and PT were tested against data reported by hourly surface observations (SAs). The measured Vk has correlated well with the SA with a correlation coefficient (r) of 0.76 for Vk < 5 km, but the FD12P underestimated visibility by about 20% with a mean difference (MD) of about 196 m. For Vk < 2 km, the FD12P overestimated visibility by about 7% with an MD of 60 m. The SA reported slightly more snow events—22% as compared to 17%—but the FD12P reported many more snow grain cases than the SA. Both the SA and the FD12P reported rain at similar frequency—4% and 5%, respectively. Using a theoretical approach, a parameterization that can be used to determine RVR as a function of Vk has been developed. Using the observed T, RH, and dewpoint temperature (Td), a new parameterization for predicting Vk/RVR in fog has been also developed. These parameterizations agreed with observations (r ≈ 0.8). The parameterizations have been tested using the Canadian Environmental Multiscale Regional model. The results show that when PI, RH, and T are reasonably predicted and the fog events are correctly diagnosed, the model can be used to forecast RVR.

“Welcome everyone to the launch of the World Women’s League of Basketball and its inaugural 10–10 tournament.” A deep male voice boomed into the darkened stadium. Strobe lights slowly swept across the space, packed with celebrities, politicians, fashionistas and media, coming to a stop illuminating a raised platform that extended most of the length of the basketball court.

We analyzed a special-purpose dataset containing times at which flights crossed concentric circles at various distances from six major US airports in July 2001. We converted the circle-crossing information into effective speeds along four flight segments defined by the circles. Working with data in 15 minute intervals, we correlated the segment speeds with runway loading, defined as expected arrival demand relative to runway capacity. We find that effective speeds of arriving traffic vary with their physical distance from the runway and their temporal distance from runway congestion. These traffic flow characterizations are made visible in a new data display developed in this paper. We thus have developed a new spatio-temporal characterization of arrival traffic flow that should be useful in efforts to understand the operation of this complex system.

Enhancements to airport surface markings were developed to facilitate pilot awareness of the runway location and to increase the conspicuity of the holding position markings, see Olmos, Andrews, and Estes (2003). The marking enhancements were evaluated in a simulation and two field studies. In a simulation study, general aviation (GA) pilots as well as transport category pilots performed taxi operations using a cockpit simulator. The simulated airport surface included enhanced surface markings and the distance at which pilots detected the runway environment was measured under various conditions. The results indicate that marking enhancements were associated with an earlier detection of the runway in some but not in all conditions. Specifically, transport category pilots detected simple taxiway-runway intersections with enhanced markings earlier than with current markings. No such perceptual advantage was found for GA pilots or at complex intersections. Most pilots, however, subjectively preferred the marking enhancements over the current marking standard. These positive evaluations of enhanced markings were confirmed by two field demonstrations where two sets of enhanced markings were implemented at two US airports. Pilots perceived the benefits of the marking enhancements to depend on pilot experience, familiarity with the airport, aircraft type, and knowledge about the marking enhancements. For certain airport situations, the enhanced markings in the hold-short environment of runways can be expected to aid pilot awareness about the runway location.

Closely spaced parallel runways(CSPRs) is the configuration mode frequently employed in planning and construction of the current airport runway. Simmod simulation software was operated here to construct the computer simulation models for different utilization patterns of runways, and made a well-organized analysis and quantitative evaluation of airport capacity and operational efficiency, given in the threshold staggering of CSPRs. Meanwhile, the effects of runway crossover and bypass-taxiing on operational efficiency of airport were also taken into account. The simulation result suggests: Abiding by IFR(instrument flight rules), a set of CSPRs are able to support 800 take-off and landing flights in peak day, while around 55~58 take-off and landing flights in peak hour. When the outside runway threshold is staggered toward the arriving aircraft and provided with the bypass taxiway, the take-off and landing efficiency of airport becomes the highest under the operational pattern(landing on the inside runway and taking off from the outside runway), about 3%~7% higher than that under any other operational pattern.

Research, development, test, and evaluation of flight deck interface technologies is being conducted by NASA to proactively identify, develop, and mature tools, methods, and technologies for improving overall aircraft safety of new and legacy vehicles operating in Next Generation Air Transportation System (NextGen). Under the Vehicle Systems Safety Technologies (VSST) project in the Aviation Safety Program, one specific area of research is the use of small Head-Worn Displays (HWDs) as an equivalent display to a Head-Up Display (HUD). Title 14 of the US Code of Federal Regulations (CFR) 91.175 describes a possible operational credit which can be obtained with airplane equipage of a HUD or an "equivalent" display combined with Enhanced Vision (EV). If successful, a HWD may provide the same safety and operational benefits as current HUD-equipped aircraft but for significantly more aircraft in which HUD installation is neither practical nor possible. A simulation experiment was conducted to evaluate if the HWD, coupled with a head-tracker, can provide an equivalent display to a HUD. Comparative testing was performed in the Research Flight Deck (RFD) Cockpit Motion Facility (CMF) full mission, motion-based simulator at NASA Langley. Twelve airline crews conducted approach and landing, taxi, and departure operations during low visibility operations (1000' Runway Visual Range (RVR), 300' RVR) at Memphis International Airport (Federal Aviation Administration (FAA) identifier: KMEM). The results showed that there were no statistical differences in the crews performance in terms of touchdown and takeoff. Further, there were no statistical differences between the HUD and HWD in pilots' responses to questionnaires.

Current Federal Aviation Administration Category I Instrument Landing System approach minima are a 200-foot above ground level Decision Height and 2,400-foot Runway Visual Range. The pilot may not commence an approach if the reported conditions are below these minimums and may only continue an approach below the decision height if the runway environment is in sight. This presentation will show that technology exists today to allow a pilot to continue his approach below published decision height to touchdown without ever actually `seeing' the runway environment outside of his cockpit. Onboard the aircraft, Global Positioning System enhanced by Wide Area Augmentation System typically provides instantaneous positional accuracy of less than one meter horizontally and 1.3 meters vertically. With this metric even the smallest aircraft could determine its location in X, Y, and Z to well within a fraction of its own footprint. Using high-precision GPS surveying equipment to perform a real-time kinematic survey, airport runway locations can be determined with centimeter level accuracy, making it conceivable to land an aircraft on a specific point on the runway to a very high degree of accuracy. Instrument flight with no outside visual cues imparts high levels of stress on the pilot. Landing an aircraft in zero-zero conditions would add significantly more stress. Synthetic Vision Systems that offer the pilot a high-fidelity representation of the outside world would lessen or preclude this stress. Many major universities, government agencies, and aerospace corporations are already at work to provide these type systems. SVS will most likely be initially designed for commercial, military, and business-class aircraft, and will cost tens to hundreds of thousands of dollars. This valuable and life-saving technology will not be affordable to most general aviation pilots. This paper proposes a reduced-cost SVS system for general aviation, based on a Microsoft WindowsTM-based tablet computer. This presentation will document the testing of this system under Visual Flight Rules conditions in order to quantify the achievable accuracy and characterize feasibility of the concept.

The rapid increase in aviation industry requires parallel effective plans, programs and designs of systems and facilities nationwide to fulfill the increasing needs for safe air transportation. Aircraft landing remains a problem for a long time all over the world. Systems that aircraft rely on in landing are unreliable to perform a precise guidance due to many limitations such as inaccuracy, unreliability and dependency. In low visibility conditions, aircrafts are diverted to another airport. However, low visibility can also affect all airports in the vicinity, forcing aircrafts to land in low visibility conditions depending on Instrument Flight Rules (IFR). Aircraft approach and landing are the most hazardous portions of flight; accidents records indicated that approximately 50 percent of the accidents occur during these portions. Aircraft landing Category IIIC is not yet in operation anywhere in the world. It requires landing with no visibility or runway visual range. Currently, Global Positioning System (GPS) is the main navigation system used all over the world for aircraft navigation, approach and landing. However, GPS accuracy is not sufficient to perform a perfect landing due to the possibility of aircraft to be drifted out of the runway. The accuracy of GPS could be improved to 3 meter by receiving correction messages. Improved accuracy has not been able to meet International Civil Aviation Organization (ICAO) standards for aircraft precision landing. In this study, aircraft landing systems characteristics, performances and accuracies have been studied and compared for the purpose of assessing limitations and drawbacks. An aircraft landing system with improved performance is proposed to meet ICAO standards for all-weather aircraft landing and to provide accurate guidance for approaching and landing aircrafts.

NASA Langley Research Center and the FAA collaborated in an effort to evaluate the effect of Enhanced Vision (EV) technology display in a commercial flight deck during low visibility surface operations. Surface operations were simulated at the Memphis, TN (FAA identifier: KMEM) air field during nighttime with 500 Runway Visual Range (RVR) in a high-fidelity, full-motion simulator. Ten commercial airline flight crews evaluated the efficacy of various EV display locations and parallax and mini cation effects. The research paper discusses qualitative and quantitative results of the simulation experiment, including the effect of EV display placement on visual attention, as measured by the use of non-obtrusive oculometry and pilot mental workload. The results demonstrated the potential of EV technology to enhance situation awareness which is dependent on the ease of access and location of the displays. Implications and future directions are discussed.

Conducting gate to gate operations during reduced visibility conditions is a major impediment to scheduled and unscheduled flight operations in the National Airspace System (NAS). Takeoff and landing minima are predicated on aircraft equipage and airport visibility (e.g., at some major airports, operations are terminated when visibility is below 700 ft runway visual range (RVR). Although some aircraft can land with zero-zero visibility, there are no ground or flight deck systems that allow them to taxi under low visibility conditions. A map display system designed to support low visibility taxi was evaluated by 12 B-747 flight crews in NASA's Crew Vehicle System Research Facility (CVSRF). Three taxi-map conditions were compared: paper map only, basic moving map, and advanced moving map. Crews landed and taxied along 24 different taxi routes under three visibility conditions: unlimited visibility, 700 ft RVR, and 300 ft RVR. Taxi time, errors and workload were collected for each taxi operation. Video tape recordings captured crew interactions and head-up and head-down times. Taxi times and errors were significantly better for crews with electronic maps than for crews with a paper map. Although crews with the advanced map experienced significantly more head-down time, the head down interval was significantly less than with the paper map and crew workload was significantly less. During the post-flight design review, pilots identified improvements in procedures and formatting that might enhance performance. They developed a procedure for safely switching from the NAV display to the map; and in general their comments were very favorable.

Flight tests performed in an A330 simulator have shown that the existing standardized Ground Based Augmentation System (GBAS) CAT I could be suitable for CAT II operations if anomalous ionospheric errors induced during solar storms could be mitigated either operationally or technically. Tests in an Airbus A330 Level D (fully certified training simulator) flight simulator were performed by EUROCONTROL in cooperation with Technical University of Berlin, to investigate whether the worst case errors of a GBAS CAT I precision approach system (10m vertical deviation) would still be acceptable for CAT II operations. Additionally similar assessment was performed for the new approach classification termed “Other Than Standard” (OTS) CAT II which allows operation of CAT II approved aircraft down to a decision height (DH) of 100 ft on runways not meeting full Cat II requirements. OTS CAT II relaxes the approach lighting requirements which is compensated by a higher required Runway Visual Range (RVR) and higher guidance performance requirements (i.e. autoland). GBAS CAT I suitability to support OTS CAT II and CAT II operation would provide a new potential benefit for airlines that have invested in a GBAS CAT I system. Those benefits could be increased access to runways served by GBAS in low visibility conditions. It could improve as well traffic flow in low visibility operation by replacing the standard Instrument Landing System (ILS), which requires larger separation on final approach during CAT II/III operations due to technical design. The tests have shown that the existing GBAS CAT I standardized system, with a Vertical Alert Limit (VAL) of 10 m as per ICAO Annex 10, would be operationally suitable for CAT II and OTS CAT II operations. The tests demonstrated that failures up to 10m vertical deviation are operationally acceptable for CAT II operations as the landing point was always well within the landing box criteria used for the demonstration of autoland systems. Lateral deviations were easily detected but pilots expressed difficulty in detecting the vertical errors. Some but not all pilots detected errors larger than 10m (i.e. 15m). The visual cues were sufficient at the decision height (DH) to conduct the OTS CAT II operation. The perception was that due to the increased RVR required for OTS CAT II, the visual cues at DH were even better in OTS CAT II conditions than in standard CAT II conditions.

The orientation of Airport runway requires information on wind speed, wind direction, and wind speed intensity and duration. On the other hand, the runway location design requires information on the latitude and longitude of the site, temperature variation at the site throughout 20 years period, and the altitude of the airport site, so that the x and y coordinates could be corrected. The design of runway requires information on the expected traffic volume, type of aircraft intending to use it, and the class of the airport as per the ICAO specifications. In this work, a computer program has been developed, with data base constructed inside, such data regarding the wind and temperature and the traffic data as explained above was fed to the data base. The latitude, longitude, and altitude of each of the eighteen provinces in Iraq were also fed to the system. A methodology for drawing the wind rose diagram and the conditions for selecting the best runway orientation through optimization process has been included in the data base. The required calculation procedures for basic runway length and the corrections usually adopted for variation of temperature and altitude, landing and takeoff situations were also fed to the data base in the system. An input sheet was designed through visual basic environment so that if an airport is required anywhere in Iraq, the system will ask for the basic data of latitude and longitude and will suggest the best orientation of the runway using the optimization technique. After suggesting the orientation, another input sheet will ask about the airport class required, the type of air craft, and the traffic volume and modes of takeoff and landing, and then the system will suggest the basic runway length required, and the required corrections to be considered for the environmental conditions. In order to check the validation of the software, Data of selected existing airports in Iraq were obtained and fed to the software so that a comparison of its output with the existing condition could be obtained. It was felt that such program will help in the management of airport design, and provide instant information regarding the runway orientation, location, and design.

The widespread placement of Runway Visual Range (RVR) visibility sensors over an airport domain provides an opportunity to expand their utility to other airport applications. These include determining visibility and inferring equivalent liquid water content snowfall rates anywhere on the airport surface. The interpolation of extinction coefficient measurements is demonstrated at Denver International Airport (DEN) and Portland International Airport (PDX). The snowfall rate determination is demonstrated at DEN, using calibration of visibility sensor extinction coefficient measurements based on an equivalent snowfall water content gauge located nearby one of the RVR visibility sensors. The snowfall rate data are shown to be useful for tracking equivalent liquid water snowfall amounts that can accumulate on an aircraft during taxiing from a deicing station to a takeoff position on a runway. This tracking of snowfall impinging on an aircraft along its designated surface route should help ensure safer deicing decision making. Furthermore, ongoing evaluation of aircraft tracks for takeoff on different runways can provide controllers with options on runway selection to enhance capacity. The time portrayal of interpolated images of visibility at DEN and PDX demonstrates how visibility can differ significantly over an airport surface and how this visibility can drift in time. Similar to the snowfall application, the interpolated visibility along surface routes to and from runways can help controllers improve estimates of times required for safe transit of aircraft during taxiing.

Traditionally, surface weather observations have been made by human observers. It has been their difficult task to estimate subjective elements such as sky cover (in tenths) and the heights of clouds (often to the nearest100 ft). Automation has moved slowly to replace subjective methods in the field and, even then, usually only in special areas such as runway visual range (RVR) and runway visibility (RVV). Recent work has demonstrated that automated observations of other subjective elements are feasible and are already operational at two points in the United States. The paper reviews the concepts of RVR and RVV, and discusses in detail new methods for the automation of cloud and visibility observations. The automated observations are compared with human products made at the same time and location. The paper points out the difficulties of assessing the success of objective techniques in comparison with subjective methods.

Low visibility is a major limiting factor on aircraft operations. Although there are several definitions of low visibility, in this paper it is defined as values less than a runway visual range (RVR) of 2400 feet. These conditions only occur a small percentage of the time, but they can have a major impact on the National Airspace System (NAS). The impact of reduced arrival rates as a result of low visibility operations at a major hub airport impacts a large geographic area. Departure airports, enroute airspace, diversion airports and adjacent smaller airports can all be significantly impacted from the reduction of capacity at the primary destination. The costs associated with the resultant delays, cancellations and diversions are substantial. The Federal Aviation Administration (FAA), in an effort to reduce these impacts and harmonize with Europe's Joint Aviation Authorities (JAA), has undertaken the task of updating the requirements for low visibility operations. This activity focuses on utilizing advanced flight deck technologies in lieu of ground based lighting and navigation components. Specific advanced flight deck technologies such as head-up displays (HUD), flight directors, auto-land systems, and enhanced flight vision systems for use in low visibility approach and landing in civil operations are being researched by the FAA and The MITRE Corporation's Center for Advanced Aviation System Development (CAASD). Benefits are enabled for operators by allowing certain Category I instrument approaches to be flown with suitable advanced flight technology in lower visibility conditions and to operate to lower decision heights. This paper reports on the extent of benefits found through analysis of weather conditions, equipage rates, demand for access, and the importance of flight schedule integrity. This paper also discusses related technologies and research that can be utilized for low visibility operations and the key considerations important to utilizing these systems for the approach and landing phases of flight.

Flight tests were conducted at Greenbrier Valley Airport (KLWB) and Easton Municipal Airport / Newnam Field (KESN) in a Cessna 402B aircraft using a head-up display (HUD) and a Norris Electro Optical Systems Corporation (NEOC) developmental ultraviolet (UV) sensor. These flights were sponsored by NEOC under a Federal Aviation Administration program, and the ultraviolet concepts, technology, system mechanization, and hardware for landing during low visibility landing conditions have been patented by NEOC. Imagery from the UV sensor, HUD guidance cues, and out-the-window videos were separately recorded at the engineering workstation for each approach. Inertial flight path data were also recorded. Various configurations of portable UV emitters were positioned along the runway edge and threshold. The UV imagery of the runway outline was displayed on the HUD along with guidance generated from the mission computer. Enhanced Flight Vision System (EFVS) approaches with the UV sensor were conducted from the initial approach fix to the ILS decision height in both VMC and IMC. Although the availability of low visibility conditions during the flight test period was limited, results from previous fog range testing concluded that UV EFVS has the performance capability to penetrate CAT II runway visual range obscuration. Furthermore, independent analysis has shown that existing runway light emit sufficient UV radiation without the need for augmentation other than lens replacement with UV transmissive quartz lenses. Consequently, UV sensors should qualify as conforming to FAA requirements for EFVS approaches. Combined with Synthetic Vision System (SVS), UV EFVS would function as both a precision landing aid, as well as an integrity monitor for the GPS and SVS database.

The Federal Aviation Administration (FAA) has long recognized the safety hazard of aircraft landing on an occupied runway. Several instances resulted in accidents, including the fatal incident at Los Angeles International Airport in February of 1991. As part of their efforts to explore new technologies to reduce these types of runway incursions, the FAA's joint safety implementation team proposed that a warning device be developed to notify pilots on approach to land that their intended runway is occupied. This concept has been called the final approach runway occupancy signal (FAROS), and recent efforts by the FAA resulted in evaluation of this technology. Long Beach Airport has been participating in an ongoing Operational Evaluation of a FAROS system since August 2006. This system utilizes surface surveillance, tracking logic and a modified precision approach path indicator (PAPI) to provide direct notification to pilots on approach that one of three activation zones on the runway is occupied. The inductive loop surveillance system monitors entry and exit points to the activation zones. When the tracking logic determines that an activation zone is occupied by a stationary or slow-moving vehicle or aircraft, the PAPI lights are flashed, providing immediate and direct notification to any pilots in the approach corridor. When the activation zone is vacated, the PAPI lights are returned to their steady state. As part of the operational evaluation (OpEval), the FAA is collecting system performance data as well as feedback from pilot observers. Together this objective and subjective data will be used to determine the effectiveness of the FAROS system to provide pilots with additional runway safety information and improving their overall situational awareness. This paper will present an overview of the FAROS system at Long Beach and discuss the data collected as part of the OpEval.

Low visibility and/or ceiling conditions have a strong impact on airports' traffic and their prediction is still a challenge for meteorologists. In this paper, the local characteristics of Low Visibility Procedure (LVP) conditions are investigated and the artificial neural network (ANN) based on resilient backpropagation as supervised learning algorithm is used to predict such meteorological conditions at Mohamed V international airport, Casablanca, Morocco. This article aims to assess the ANN ability to provide accurate prediction of such events using the meteorological parameters from the Automated Weather Observation Station (AWOS) over the period from January 2009 to March 2015. First, LVP conditions were classified according to their classes (fog LVP and no fog LVP) and their sources (Runway Visual Range -RVR LVP-, Ceiling -HCB LVP- or both) for both runway end points (35R and 17L). It is found that most of LVP conditions are associated with fog and are often due to decreasing of RVR below 600m. Next, Eleven ANNs were developed to produce LVP prediction for consecutive hourly valid forecast times covering the night and early morning. The Multi-Layer Perceptron (MLP) architecture with one hidden layer is used in this study. Results show that ANNs are able to well predict the LVP conditions and are robust to errors in input parameters for a relative error below 10%. Furthermore, it is found that the ANN's skill is less sensitive to LVP type being predicted.

Fog is a significant factor affecting the Air Traffic Control (ATC). Significant limitations of the airport capacity are due to fog that causes the reduction of the visibility (Runway Visual Range, RVR). Today METAR (Meteorological Aviation Report) and forecasts TAF (Terminal Aerodrome Forecast) are only available to estimate the visibility variations, but not to estimate the RVR. Scope of this paper is to evaluate the performance of airport radar sensors to detect the fog.

When an monocular vision-based unmanned aerial vehicle (UAV) based on vision is flown to the final approach fix to intercept the glide slope without the navigation of Global Positioning System (GPS), the position and orientation of the airport runway in image must be detected accurately so as to a host of suitable procedures have to be followed. The optimum length of the final approach is about five miles from the runway threshold. The front view of the runway, which is achieved at the moment, is very illegible. The approaching marking (cross bar) of the runway are showed as some white spots of high intensity and the complicated backgrounds of the airport are included in the images. In this case, spots with high intensity should be extracted and classified, some of these spots are just the images of the background noises and the pseudo-targets, which can't be separated with the spots of the runway as in the view there is no significant characteristic difference among them ostensibly. Fortunately, in the terrestrial coordinate space, most of the runway marks are located at the apexes of a rectangle, having some geometric relationships. The relationship among the projection coordinates of the runway spots in the images can be determined according to the perspective principle, the constraint condition of the rectangle as well as the front shot constraint condition of the target, by using this relationship, the runway approaching marks can be separated, the position and the direction of the runway in the images can be identified. In this paper, the clustering management is adopted so as to greatly reduce the computing time. The consequence of the experiments shows that by this algorithm, even from a place far away from the runway whose marks are unclear, we also can effectively detect the runway.

The Federal Aviation Administration (FAA) is working to reduce runway incursions in the National Airspace System (NAS). This effort to enhance safety at our nation’s airports is one of the Agency’s highest priorities. As each airport is unique, the FAA maintains standards to ensure consistency for airport visual aids from airport to airport in the NAS. These critical tools serve as visual cues to pilots during airport surface movement. To support the Agency’s safety goals, the FAA Surface Systems Office is conducting research to identify new airport visual aids that may increase overall airport surface safety. This research includes an Enhanced Airport Lighting (EAL) research and development project to assess the use of runway guard lights (RGLs) as runway incursion prevention tools. Introduction RGLs have been part of the NAS since 1992. These flashing yellow lights located at the runway holding position provide visual cues that alert both pilots and vehicle operators that they are about to enter a runway. The current FAA requirement is to use RGLs with less than 1200 feet runway visual range (RVR) as a part of the Surface Movement Guidance and Control System (SMGCS). The EAL project has been undertaken to identify any potential benefits that may be obtained by using RGLs under non-SMGCS conditions, specifically to increase situational awareness. The EAL Project The EAL project promotes the use of airport visual aids to increase overall situational awareness on the airport surface, more specifically in the airport movement area. The current standard for visual cues to help pilots identify runway holding positions includes painted surface holding position markings and holding position signs. In some cases, various airport configurations, visibility conditions, and other obstructions may complicate a pilot’s ability to determine the location of the runway holding position. To address these conditions, the EAL project has two goals: (1) to identify additional visual aids to increase pilot’s ability to recognize the runway holding position and (2) to identify technologies that will increase overall situational awareness at our nation’s airports. The test EAL system, which requires no Air Traffic Control (ATC) intervention, has been installed at North Las Vegas Airport (VGT). The system consists of three different configurations of runway guard lights: • Elevated runway guard lights • In-pavement runway guard lights • In-pavement “T” configuration of runway guard lights. The lights are collocated with the standard runway holding position paint markings and signage at all 29 runway/taxiway holding positions throughout the entire airport. Controlled studies conducted at VGT by the Air Safety Technology Office of William J. Hughes Technical Center have quantitatively demonstrated the effectiveness of RGLs as a runway incursion prevention tool. In one case, on Taxiway Alpha 1, the pilot acquisition range more than doubled (209%) from 750 feet to 1170 feet during nighttime taxi operations with the addition of RGLs. In addition to the test at VGT, the EAL Team conducted an overall data assessment of other airports that have RGLs. By looking at the runway incursion history of these airports both before and after RGL installation, several trends are apparent. Although the total number of incursions was not reduced, RGL installation has helped 1 ATO Office of Technology Development, 800 Independence Ave, SW AIAA 5th Aviation, Technology, Integration, and Operations Conference (ATIO) 26 28 September 2005, Arlington, Virginia AIAA 2005-7332 This material is declared a work of the U.S. Government and is not subject to copyright protection in the United States. to reduce the severity of incursions. The data shows fewer Category A and B incursions, with a corresponding increase in Category C or D incursions. This equates to improved safety, and is a uniform finding across the entire range of airports. As a result of the findings derived from the above efforts, the EAL Team is prepared to offer a series of recommendations: 1. The FAA application of RGLs should be modified to include their use as a runway incursion prevention tool independent of weather conditions. 2. Airports that currently have RGLs should turn them on during all operations. 3. RGLs should be powered during installations such that they can be operated independently of other lighting systems. 4. The FAA should consider making RGLs available to airports specifically for runway incursion prevention when recommended by the local Runway Safety Action Team (RSAT).

This paper describes the proposed agent-based architecture of the Aviation Data Integration System (ADIS). ADIS is a software system that provides integrated heterogeneous data to support aviation problem-solving activities. Examples of aviation problem-solving activities include engineering troubleshooting, incident and accident investigation, routine flight operations monitoring, safety assessment, maintenance procedure debugging, and training assessment. A wide variety of information is typically referenced when engaging in these activities. Some of this information includes flight recorder data, Automatic Terminal Information Service (ATIS) reports, Jeppesen charts, weather data, air traffic control information, safety reports, and runway visual range data. Such wide-ranging information cannot be found in any single unified information source. Therefore, this information must be actively collected, assembled, and presented in a manner that supports the users problem-solving activities. This information integration task is non-trivial and presents a variety of technical challenges. ADIS has been developed to do this task and it permits integration of weather, RVR, radar data, and Jeppesen charts with flight data. ADIS has been implemented and used by several airlines FOQA teams. The initial feedback from airlines is that such a system is very useful in FOQA analysis. Based on the feedback from the initial deployment, we are developing a new version of the system that would make further progress in achieving following goals of our project.

Runway roughness affects primarily ride quality and dynamic wheel loads. The forces applied onto the airport pavement by aircraft vary instantaneously above and blow the static weight, which in turn increase the runway roughness. One method to effectively assess the ride quality of the airport runway is to measure its longitudinal profile and numerical simulate aircraft response performing a takeoff, landing or taxiing on that profile data. In this study the aircraft responses excited as the aircraft accelerates or moves at a constant speed on the runway during takeoff and taxi are computed by using the improved computer program TAXI. This procedure is capable of taking into account both the effects of discrete runway bumps and runway roughness. Thus, sections of significant dynamic response can be determined, and the maintenance and rehabilitation works for airport runways will be conducted.

Researchers at Stanford University have developed and flight tested a runway incursion alerting system for aircraft on final approach. The system utilizes synthetic vision and ADS-B. The objectives of the flight test were to conduct a proof of concept and to compare the reaction times to incursion between pilots looking out the window and pilots looking at the display. In April 2001 we flew 98 approaches (incursions occurred on 72 approaches) into Moffett Federal Airfield. A specially equipped Ford Winstar Van generated the incursions while a Cessna Caravan flew approaches. Pilots looking out the window tended to see incursions at the runway threshold before the pilot using the display. The reaction time of the out the window pilot was a function of visibility conditions and the location of the incursion along the runway. The reaction time of the pilot looking at the synthetic vision display was insensitive to these factors.

At least 43 major airports in the US have parallel runways that are in very close proximity to each other - less than 4,400 feet apart. During visual meteorological conditions (VMC), when visual contact between aircraft is possible, airport capacity is greatly increased by having aircraft fly closely spaced parallel visual approaches. Under instrument meteorological conditions (IMC), airports with runways closer than 4,400 feet are required to revert to a single runway operation or to run dependent approaches. Each of these traffic flows greatly reduces the number of landing aircraft, sometimes by as much as 50%. This study examined the operational implementation of an airborne system which would support closely spaced parallel approach operations at airports with parallel runway center lines as close as 2,500 feet during IMC. Additionally, the study examined the system's requirements, both flight deck and ATC, that would support the implementation of closely spaced parallel approach operations at a major HUB airport. The primary objective of the AILS (airborne instrument landing system) concept is to enable safe independent approaches to parallel runways with runway spacing of at least 2,500 feet, through the development of concepts, procedures, and supporting technology.

In order to improve the precision and enlarge the measuring range of Digital Photography Visiometer (DPV) in the daytime, a bi-blackbody algorithm is derived to eliminate the effects of dark current of CCD camera and stray light of background. Some experiments have been performed to compare DPV with one VAISALA FD12 visibility meter and one VIASALA MITRAS Runway Visual Range Assessment System at Luogang Airport, Hefei, in 2002. Plentiful results showed that these instruments work consistently within a reasonable precision when the visibility varies from 50m to 20km. The further experiments proved that DPV with the bi-blackbody algorithm is feasible and reliable at least in the range of 200 times of baseline length.

The aviation industry has long sought a means of conducting all weather operations. Presently, airport lighting systems provide the only means for aiding the pilot's transition from instrument to visual acquisition of the runway environment prior to landing the aircraft. The ability for a pilot to see through fog (cloud ceiling and visibility) define the limitations for conducting operations in instrument meteorological conditions. CAT I approaches are authorized down to a runway visual range (RVR) of 2,400 feet, while CAT IIIa approaches are authorized to an RVR of 700 ft. Enhanced vision technologies are being investigated to improve the ability of the pilot to acquire the visual cues (predominantly airport lighting systems) to the runway environment. If enhanced vision enabled the pilot to see 3.5 times farther than the unaided eye, CAT I operations could be conducted under CAT IIIa conditions. This paper examines the relative theoretical and experimental performance of several enhanced vision technologies. This performance analysis compares the runway light detection capability of various infrared sensors with the eye during the dynamics of an aircraft approach and landing. This analysis further compares the IR performance with FogEye, a UV sensor, and a Laser Visual Approach system.

Runway occupancy time (ROT) data are essential to effectively monitor current airport operating efficiencies and to plan for the introduction of new aircraft surface movement guidance and control systems. This study was commissioned to provide a large and useful set of current ROT data for a major airport that could be used to support analyses aimed at improving the efficiency and safety of surface operations. This study was conducted at Atlanta's Hartsfield International Airport using the NASA Dynamic Runway Occupancy Measurement System (DROMS). Analyses were conducted to determine the factors that determine ROT such as aircraft weight, velocity, air carrier, and meteorological conditions.

A flight demonstration was conducted in August 1997 at the Hartsfield Atlanta (ATL) International Airport as part of low visibility landing and surface operations (LVLASO) research activities. This research was aimed at investigating technology to improve the safety and efficiency of aircraft movements on the surface during the operational phases of roll-out, turnoff, and taxi in any weather condition down to a runway visual range of 300 feet. The system tested at ATL was composed of airborne and ground-based components that were integrated to provide both the flight crew and controllers with supplemental information to enable safe, expedient surface operations. Experimental displays were installed on a Boeing 757-200 research aircraft in both head-up and head-down formats. On the ground, an integrated system maintained surveillance of the airport surface and a controller interface provided routing and control instructions. While at ATL, the research aircraft performed a series of flight and taxi operations to show the validity of the operational concept at a major airport facility, to validate simulation findings, and to assess each of the individual technologies' performance in an airport environment. The concept was demonstrated to over 100 visitors from the Federal Aviation Administration (FAA) and the aviation community. This paper gives an overview of the LVLASO system and ATL test activities.

An A-SMGCS architecture and operational concept is presented that has been designed to prevent runway incursions while also improving operational capability. Results of a full-mission simulation using 18 airline pilots and six air traffic controllers are presented along with a description of flight testing to be performed at the Dallas-Fort Worth International Airport. During the simulation, pilot test subjects executed multiple approaches followed by taxi to the gate in visibilities down to 150' using a synthetic vision display system. This system consists of a head-up display providing tactical guidance and a head-down moving map with position, traffic, and ATC instructions depicted to improve situational awareness in the flight deck. Runway incursion warnings were also generated in the flight deck based on surface traffic positions. Simulation scenarios modeled peak traffic conditions and included typical runway incursion events during both landing and takeoff roll. Results are presented as a function of visibility.

This article deals with the exploration of GA aerodromes around the world that meet the defined input conditions of maximal 1,500 m long runway and the existence of straight-in instrument approach. These aerodromes are analysed from different perspectives of runway equipment with respect to the various types of published approach.

Runway incursions have been declared the nation's foremost aviation safety issue by the National Transportation Safety Board and the Federal Aviation Administration in testimony before congressional aviation committees. Technology solutions to date have been disappointing. After 12 years of development, the frequency of runway incursions shows no sign of abating, even as the cost for such systems continues to rise beyond $DLR9 million per airport. Application of ultraviolet technology offers incremental, low-cost, near- term improvements in runway incursion prevention and other enhancements to aviation safety, as well as increases in airport throughput capability, i.e., a reduction in delays.