Landing Phases Of Flight Research Articles

Image-based UAV position and velocity estimation using a monocular camera

Autonomous landing of aerial vehicles is challenging, especially in emergency flight scenarios in which precise information about the vehicle and the environment is required for near-to-ground maneuvers. In this paper, the optic-flow concept based on feature detection is applied to estimate the vertical distance and the velocity vector of a multirotor UAV (MUAV) for landing. The UAV kinematics, the optical flow equations, and the detected feature states, provided by a low-cost monocular camera, are combined to develop a novel appropriate model for estimation. The proposed algorithm applies the variation of detected features, the angular velocities, as well as the Euler angles, measured by the Inertial Measurement Unit (IMU), to estimate the vertical distance of the UAV to the ground, the MUAV velocity vector, and also to predict the future features position. Extended Kalman filter (EKF) is applied as the estimation method on the coupled optic-flow and kinematic equations. The accuracy of state estimation is enhanced by the idea of multiple-feature tracking. The 6-DOF simulations, laboratory experiments, and comparison of results demonstrate the capability of height and velocity estimation of a MUAV in the landing phase of flight by just applying the low-cost camera information. Monte Carlo simulations have been performed to study the effect of IMU acceleration, and angular velocity measurement noises as well as the number of the detected features on the success probability of the estimation process. The results reveal that increasing the number of detected features, i.e tracking multiple features, increases the estimation accuracy, however, it mainly improves the success probability, which is a more important factor in practical scenarios.

TRIPLE PROBABILITY DENSITY DISTRIBUTION MODEL IN THE TASK OF AVIATION RISK ASSESSMENT

The probability of an airplane deviation from pre-planned trajectory is a core of aviation safety analysis. We propose to use a mixture of three probability density distribution functions it the task of aviation risk assessment. Proposed model takes into account the effect of navigation system error, flight technical error, and occurrence of rare events. Univariate Generalized Error Distribution is used as a basic component of distribution functions, that configures the error distribution model from the normal error distribution to double exponential distribution function. Statistical fitting of training sample by proposed Triple Univariate Generalized Error Distribution (TUGED) is supported by Maximum Likelihood Method. Optimal set of parameters is estimated by sequential approximation method with defined level of accuracy. The developed density model has been used in risk assessment of airplane lateral deviation from runway centreline during take-off and landing phases of flight. The efficiency of the developed model is approved by Chi-square, Akaike’s, and Bayes information criteria. The results of TUGED fitting indicate better performance in comparison with double probability density distribution model. The risk of airplane veering off the runway is considered as the probability of a rare event occurrence and is estimated as an area under the TUGED.

Assessment of the GIS-Aided Precise Approach Using the GNSS-GBAS Landing Systems

The radio navigational Instrument Landing Systems (ILSs) are currently intended to guide the aircrafts in lateral and vertical dimensions to the runway surface safely and precisely. Therefore, they are strongly related to the geographic location of an airport and its runway(s). The ILS systems use the aids of the radio frequency radiation to achieve this purpose, depending on the ground emitting stations, and providing the guidance to the runway centreline location along with the glide slope guidance during the Final Approach Segment (FAS). Furthermore, the new ILS systems are fully aided by the coordinates of the Global Positioning System (GPS) instead of the ground radiations, they use the waypoint fixes during the landing phase of flight by means of transmitting their corrections to the on-board receivers. Those new invented Ground Based Augmentation Systems (GBAS) are more precise and trustable, they also increase the capacity of the huge air traffic demands nowadays by multiple and non-straight approaches. As a result, the Geographic Information System (GIS) of any airport supported by the GBAS system is intended to be fully used and implemented in both instrumental and procedural aids. Many previous studies had indicated that the old procedural approaches should be changed to the new GIS aided ones, but without pointing out when and how to implement such important transfer. The purpose of this study is to assess the performance of the GIS aided precision procedures using the GBAS stations, and to identify to what extent they can enhance the navigational aviation in the air traffic management domain. A special focus will be put on the Hungarian Budapest international airport in terms of both capability motivating factors and the current GIS infrastructure aiding. Results showed a promising chance for more investment in installing the GBAS stations in the airport. That will enable more capacity and easier approaches in all weather conditions.

A new active asymmetry monitoring and control technique applied to critical aircraft flap control system failures

Asymmetry limitation requirements between left and right wing flap surfaces play an important role in the design of the implementation of the secondary flight control system of modern airplanes. In fact, especially in the case of sudden breaking of one of the torsion bars of the flap transmission line, the huge asymmetries that can rapidly develop could compromise the lateral-directional controllability of the whole aircraft (up to cause catastrophic occurrences). Therefore, in order to guarantee the aircraft safety (especially during take-off and landing flight phase in which the effects of asymmetries could generate uncontrollable aircraft attitudes), it is mandatory to timely detect and neutralize these asymmetries. The current monitoring techniques generally evaluate the differential angular position between left and right surfaces and, in most the events, limit the Flaps Control System (FCS) asymmetries, but in severe fault conditions (e.g. under very high aerodynamic loads), unacceptable asymmetries could be generated, compromising the controllability of the aircraft. To this purpose, in this paper the authors propose a new active monitoring and control technique capable of detecting the increasing angular error between the different flap surfaces and that, after stopping the whole actuation system, acts on the portion of the actuation line still connected to the PDU to minimize the FCS asymmetries.

Numerical Model and Forecasting Potential of Aircraft Weather Hazards over Kenya

The study investigated the forecasting potential of aircraft weather hazards over Kenya using numerical model. The various causes of accidents/incidents were identified using analyzed investigated weather-related aviation hazards data obtained from Kenya Civil Aviation Authority database system from 2008 through 2014. The parameters analyzed included the Winds, Temperature, Relative humidity, Convective Available Potential Energy (CAPE), Lifted Index (LI) and Dew Point Temperature. Their combined effect was able to provide the means of identifying the areas of strong convection. The model was run on a grid point distance resolution of 10 km and runs finite differencing scheme, based on Taylor series. Grid Analysis and Display System (GrADS) which is embedded on the model upon installation, was used as the default post processing tool. Key findings revealed that Wind, Fog, Turbulence, Heavy rain showers, and low ceiling influenced aircraft operations. It was shown that the majority of the hazards were linked with cumulonimbus clouds. Landing phase of flight affected aviation most.

High AOA short landing robust control for an aircraft

Purpose The purpose of this paper is to propose a high angle of attack short landing model for switched polytopic systems as well as to derive an equation for fluidic thrust vector deflection angle based on pressure to reduce the velocity during the landing phase of flight. Design/methodology/approach In this paper, robust control algorithm is proposed for a non-linear high angle of attack aircraft under the effects of non-linearities, tottering hysteresis, irregular and wing rock atmosphere. High angle of attack short landing flight under asynchronous switching is attained by using the robust controller method. Lyapunov function and the average dwell time scheme is used for obtaining the switched polytopic scheme. The asynchronous switching and loss of data are controlled asymptotically. The velocity of aircraft has been lucratively reduced during the landing phase of flight by using the robust controller technique. Findings The proposed algorithm based on robust controller including the effects of non-linearities guarantee the successful reduction of velocity for high angle of attack switched polytopic systems. Practical implications As the landing phase of an aircraft is one of the complicated stage, this algorithm plays a vital role in stable and short landing under the condition of high angle of attack (AOA). Originality/value In this paper, not only the velocity of flight has been reduced, but also the high angle of attack has been attained during the landing phase, because of which the duration of landing has been reduced as well, while in most of the previous research, it is based on low angle of attack and long landing duration.

Результати аналізу функцій розподілу для оцінки густини ймовірності розміщення місць авіаційних подій в околиці аеропорту

Стаття містить результати обробки та статичного аналізу даних про місця розміщення авіаційних подій важких та легких повітряних суден, які сталися протягом 1973–2013 рр. Представлено розподіл розміщення місць авіаційних подій під час виконання різних етапів польоту поблизу аеропорту. Показано результати аналізу функцій розподілу для оцінки густини ймовірності розміщення місць авіаційних подій під час зльоту і посадки. Розподіли Вейбула і Гама визначені як такі, що з найбільшою достовірністю відповідають опису густини ймовірності розміщення місць авіаційних подій уздовж поздовжніх і поперечних координат відносно вісі злітно-посадкової смуги. Отримані статистичні характеристики місць, де трапляються авіаційні події під час зльоту і посадки повітряних суден в околиці аеропортів.

Robust Landing and Sliding Maneuver Hybrid Controller for a Quadrotor Vehicle

This paper addresses the design and experimental evaluation of a robust controller for a quadrotor landing maneuver comprising the approach to a landing slope and sliding on that slope, before coming to a complete halt. During the critical landing flight phase, the dynamics of the vehicle change with the type of contact with the ground, and a hybrid automaton, whose states reflect the several dynamic behaviors of the quadrotor, is employed to model the vehicle throughout the complete maneuver. The quadrotor landing problem is broken down as separate maneuver generation and robust trajectory tracking problems, which are combined to achieve a successful maneuver that is robust to possible uncertainties. The experimental results are provided to attest to the feasibility of the proposed landing procedure.

Crew Resource Management Application in Commercial Aviation

The purpose of this study was to extend previous examinations of commercial multi-crew airplane accidents and incidents to evaluate the Crew Resource Management (CRM) application as it relates to error management during the final approach and landing phase of flight. With data obtained from the Federal Aviation Administration (FAA) and the National Transportation Safety Board (NTSB), a x 2 test of independence was performed to examine if there would be a statistically significant relationship between airline management practices and CRM-related causes of accidents/incidents. Between 2002 and 2012, 113 accidents and incidents occurred in the researched segments of flight. In total, 57 (50 percent) accidents/incidents listed a CRM-related casual factor or included a similar commentary within the analysis section of the investigation report. No statistically significant relationship existed between CRM-related accidents/incidents

Unusual Neurological Syndrome Induced by Atmospheric Pressure Change

We describe a case of a 46-yr-old female who developed hypertension, tachycardia, dysarthria, and leg weakness provoked by pressure changes associated with flying. Typically during the landing phase of flight, she would feel dizzy and note that she had difficulty with speech and leg weakness. After the flight the leg weakness persisted for several days. The symptoms were mitigated when she took a combined alpha-beta blocker (labetalol) prior to the flight. To determine if these symptoms were related to atmospheric pressure change, she was referred for testing in a hyperbaric chamber. She was exposed to elevated atmospheric pressure (maximum 1.2 ATA) while her heart rate and blood pressure were monitored. Within 1 min she developed tachycardia and hypertension. She also quickly developed slurred speech, left arm and leg weakness, and sensory changes in her left leg. She was returned to sea level pressure and her symptoms gradually improved. A full neurological workup has revealed no explanation for these findings. She has no air collections, cysts, or other anatomic findings that could be sensitive to atmospheric pressure change. The pattern is most consistent with a vascular event stimulated by altitude exposure. This case suggests that atmospheric pressure change can produce neurological symptoms, although the mechanism is unknown.

High Fidelity Antenna Model Validation Results of a GNSS Multipath Limiting Antenna

The local area augmentation system (LAAS) is a proposed satellite-based landing system by the Federal Aviation Administration (FAA) to serve as a navigation aid for commercial aircraft during the approach and landing phase of flight. The LAAS utilizes a special ground-based antenna array called the multipath limiting antenna (MLA) to provide differentially corrected global navigation satellite system (GNSS) data to oncoming aircraft as well as to reduce the largest error contributor to pseudo-range estimates; the ground multipath. The performance of the MLA is characterized in terms of its desired-to-undesired (D/U) gain ratio, phase center variation (PCV) and group delay (GD). A high fidelity antenna model (HFAM) of the MLA is presented that estimates the D/U, PCV, and GD as a function of elevation angle. The model consists of two main components: (1) a microwave feed distribution circuit model created using a circuit simulator, and (2) a radiating structure model developed using a full-wave method of moments (MoM) field solver. The performance of the model was assessed against antenna range measurements. The results of the HFAM show good correlation for the D/U and PCV while a significant bias was observed on the results for the GD. The dependence of the GD on the radiating element's impedance, tuning process, and Doppler frequency shift are demonstrated via simulations.

Aircraft accidents and incidents associated with visual effects from bright light exposures during low-light flight operations

Introduction Preservation of optimal night vision is important for pilots operating aircraft in low-light conditions. This study investigates operational problems experienced by civilian airmen exposed to bright light sources while performing nighttime aviation activities. Methods The National Transportation Safety Board (NTSB) Aviation Accident and Incident Data System and the Federal Aviation Administration (FAA) Accident/Incident Data System were queried using terms associated with night vision problems. Accident and incident reports annotated with 1 or more of these terms were reviewed to determine whether exposure to bright lights at night may have contributed to the mishap. Results Vision problems resulting from exposure to bright lights at night contributed to 58 mishaps. Reports included 30 (NTSB) accidents and 28 (FAA/NTSB) incidents. The majority of accidents (57%) occurred during the approach and landing phase of flight. Incidents occurred most frequently while taxiing (54%) and during approach and landing (36%). Conclusions Exposure to bright light sources at night has contributed to aviation accidents and incidents. The information in this study may assist airport authorities in identifying and eliminating hazardous lighting near flight paths and surface movement areas. Preventive measures for avoiding conditions that compromise the safety of aviation operations at night are discussed.

Flight Envelope Expansion in Landing Phase Using Classic, Intelligent and Adaptive Controllers

An expanding flight envelope in the landing phase of a typical jet transport aircraft in presence of strong wind shears using a learning capable control system (LCCS) is investigated. The idea stems from human beings functional architecture that gives them the ability to do more as they age and gain more experience. With the knowledge that classical controllers lack sufficient generality to cope with nonlinear as well as uncertain phenomenon such as turbulent air, the focuse is on different types of intelligent controllers due to their learning and nonlinear generalization capabilities as candidates for the landing flight phase. It is shown that the latter class of controllers could be used to enable the aircraft to learn and gain experience as they land more and more in gusty conditions. This capability enables the aircraft to land in conditions slightly more severe than previous experiences, and hence, as far as the landing phase is concerned, the flight envelop is expanded as the aircraft ages. In this regard, five controllers including a classical proportional‐integral‐derivative (PID) plus three intelligent controllers, in addition to an adaptive one, are presented and compared, based on neural networks and fuzzy logic concepts. The robustness and performance of the controllers are evaluated by applying two different strong wind patterns for two levels of performance.

A Relative Technique for Characterization of PCV Error of Large Aperture Antennas Using GPS Data

The Federal Aviation Administration's (FAA) local area augmentation system (LAAS) is a code-based differential global positioning system (DGPS) to be used for guidance of aircraft during the approach and landing phase of flight. Code-based multipath error was a limiting factor in the LAAS meeting category III accuracy requirements for this phase of flight. Consequently, a large aperture antenna was proposed for use at each ground-based DGPS reference site to reduce the impact of code-based multipath error to less than 0.25 m. The large aperture antenna accomplishes this task at the expense of providing limited coverage in the vertical plane (0-35/spl deg/). An ancillary high-zenith antenna is then necessary to track satellites from 35-90/spl deg/ in elevation. Phase center variation (PCV) has been observed to be a significant source of GPS error when translating the accumulated carrier phase (ACP) and pseudorange (PR) data between the two aforementioned antennas to a common phase center. This paper presents a relatively simple method for reducing the error caused by the PCV of a large aperture antenna. This is done by comparing the GPS ACP data from a large aperture vertically polarized dipole array antenna with undesirably large PCV (more than 20 cm), with similar data from a right-hand circularly polarized high-zenith antenna with small PCV (relative to physical center of array). A triple-differencing technique of the ACP data between the two antennas across successive epochs is used to characterize the PCV of the large aperture antenna as a function of elevation angle. The PCV correction factor is applied to the ACP data from the large aperture antenna array. The ACP data from the two antennas are then combined in software to appear as one antenna with minimal offset from PCV. A field test that employed this technique is described and test results are provided. This technique confers an advantage over other methods for PCV determination, which require precision mounting and/or robotic motion capabilities, or the use of an antenna range.

Hot-air ballooning injuries in the United Kingdom (January 1976–January 2004)

Objectives: Injuries due to hot-air ballooning accidents are uncommon but may be severe. In this study we examined the factors contributing to ballooning accidents in the UK and the type of injuries sustained. Methods: The post-investigation reports of ballooning accidents from 1976 to 2004 were reviewed. They were analysed to determine type and severity of injuries, phase of flight at time of accident and causative or contributory factors. Results: Sixty-one people were seriously injured in 98 ballooning accidents, with 2 fatalities. The majority of these accidents occurred during the approach and landing phase of flight. Ground collisions and crashes with power lines accounted for the majority of accidents. Adverse weather conditions were present in a significant number of crashes. Equipment failure was an uncommon cause of accidents. Fractures and burns were the most common form of injuries sustained. Conclusions: Changes in design and materials used, as well as adherence to specific recommended safety protocols, may aid to decrease the risk of severe burns in ballooning accidents. We discuss these factors illustrated by our experience of the worst recorded ballooning accident in Britain.

Fuzzy Logic Trajectory Design and Guidance for Terminal Area Energy Management

The second generation reusable launch vehicle will leverage many new technologies to make flight to low earth orbit safer and more cost effective. One important capability will be completely autonomous flight during reentry and landing, thus making it unnecessary to man the vehicle for cargo missions with stringent weight constraints. Implementation of sophisticated new guidance and control methods will enable the vehicle to return to earth under less than favorable conditions. The return to earth consists of three phases--Entry, Terminal Area Energy Management (TAEM), and Approach and Landing. The Space Shuttle is programmed to fly all three phases of flight automatically, and under normal circumstances the astronaut-pilot takes manual control only during the Approach and Landing phase. The automatic control algorithms used in the Shuttle for TAEM and Approach and Landing have been developed over the past 30 years. They are computationally efficient, and based on careful study of the spacecraft's flight dynamics, and heuristic reasoning. The gliding return trajectory is planned prior to the mission, and only minor adjustments are made during flight for perturbations in the vehicle energy state. With the advent of the X-33 and X-34 technology demonstration vehicles, several authors investigated implementing advanced control methods to provide autonomous real-time design of gliding return trajectories thus enhancing the ability of the vehicle to adjust to unusual energy states. The bulk of work published to date deals primarily with the approach and landing phase of flight where changes in heading angle are small, and range to the runway is monotonically decreasing. These benign flight conditions allow for model simplification and fairly straightforward optimization. This project focuses on the TAEM phase of flight where mathematically precise methods have produced limited results. Fuzzy Logic methods are used to make onboard autonomous gliding return trajectory design robust to a wider energy envelope, and the possibility of control surface failures, thus increasing the flexibility of unmanned gliding recovery and landing.

Computation of GPS continuity with consideration of progress of time

AbstractThe international civil aviation organization (ICAO) has defined the international standard for the global navigation satellite system (GNSS) based on GPS for aviation use. Navigation systems for aviation must ensure not only the specific positioning accuracy but also the required reliability performance. Continuity is one of the measures of system reliability, and is defined as the probability that the system operates without nonscheduled interruptions over a certain period of time. We have already proposed a method of computing the continuity of GPS for the approach and landing flight phase. However, the method cannot be applied to flight phases such as enroute or terminal airspace because of the longer periods for such phases, for example 1 hour, over which the continuity requirements are defined. This paper describes a method of computing continuity with consideration of the progress of time, taking into account the movement of the aircraft relative to navigation satellites. Some computation examples are also presented. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(3): 26–34, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10044

The Application of a Smart Landing Gear Oleo Incorporating Electrorheological Fluid

The objectives of this paper are to outline the use of Electrorheological (ER) fluid within an aerospace system. The advantages of ER fluid-based systems are given followed by design considerations which include those related to the non-linear behaviour of an ER fluid subjected to oscillatory shear. A control strategy is outlined for the use of a smart landing gear (LG) oleo incorporating ER fluid. The paper also considers the issues associated with airworthiness requirements and ER fluid devices. For airworthiness approval a smart oleo based LG system must primarily be shown to be safe and as such has to be fault tolerant. A major failure for this application would be if the control strategy failed and the oleo damping coefficient was consistently too low; a backup system is therefore incorporated into the design and other potential modes of failure considered. A semi-active control strategy applied to a variable damping coefficient LG oleo has specific requirements, partly due to the fact that for the take-off and landing phases of flight they are different. A semi-active control strategy is outlined based on the requirements for the alteration of damping coefficient according to the phase of an aircraft's flight. The strategy is the focus of current work to estimate the effectiveness of semi-active vibration control as applied to an undercarriage.

Loop separation parameter - A new metric for landing flying qualities

Loop Separation Parameter is a metric used to evaluate the longitudinal flying qualities of aircraft in the landing flight phase. It combines simple pilot models with classical root locus and frequency response methods to predict Cooper-Harper pilot ratings for aircraft in the landing phase. Loop Separation Parameter was originally developed using fighter-type aircraft flight test data; in this paper the concept is extended and shown to be a good tool for predicting pilot ratings for large bomber, transport, and highly augmented Space Shuttle configurations. Loop Separation Parameter anticipates the tendency for and predicts the frequency of pilot-induced oscillations. The effects of control system time delay and altitude lag time constant are discussed. It is recommended that Loop Separation Parameter be included in the Flying Qualities Handbook. .

In-flight investigation of large airplane flying qualities for approach and landing

Abstract : A study of the handling qualities of large airplanes in the approach and landing flight phase was performed. An in-flight simulation experiment utilizing the USAF-AFWAL/Calspan Total In-flight Simulator was carried out to gather data for the analysis effort. A one-million pound statically unstable airplane model was used as a baseline about which variations were made. The primary variables were relative pilot position with respect to center of rotation, command path time delays and phase shifts, augmentation schemes and levels of augmentation. Both longitudinal and lateral-directional characteristics were investigated. The experiment design, conduct of the experiment, and analysis of the data are described. Results are presented in the form of pilot ratings, pilot comments and various analysis techniques. The results indicate that the approach and landing task with very large airplanes is a fairly low bandwidth task. Low equivalent short-period frequencies and relatively long time delays can be tolerated. As the pilot position is moved aft towards and then behind the center of rotation, pilot position is moved aft towards and then behind the center of rotation, pilot ratings are degraded. A multiloop analysis of pitch attitude and altitude control gave insight into this pilot position phenomenon.