Take-off Times Research Articles

Arrival and Departure Sequencing, Considering Runway Assignment Preferences and Crossings

Aircraft sequencing has the potential to decrease flight delays and improve operational efficiency at airports. This paper presents the aircraft sequencing problem (ASP) on multiple runways with complex interactions by allocating flights on runways and optimizing landing times, take-off times, and crossing times simultaneously in a uniform framework. The problem was formulated as a mixed-integer program considering realistic operational constraints, including runway assignment preferences based on the entry/exit fixes of the terminal maneuvering area (TMA), minimum runway separation, time window, and arrival crossing rules. Variable-fixing strategies were applied, to strengthen the formulation. A first-come-first-served (FCFS) heuristic was proposed for comparison. Various instances from the literature and from realistic data sets were tested. Our computational study showed that the solution approach optimizes runway schedules, to achieve significantly fewer flight delays, taking runway assignment preferences and arrival crossings into account.

Impacts of Vaccination and Severe Acute Respiratory Syndrome Coronavirus 2 Variants Alpha and Delta on Coronavirus Disease 2019 Transmission Dynamics in Four Metropolitan Areas of the United States.

To characterize Coronavirus Disease 2019 (COVID-19) transmission dynamics in each of the metropolitan statistical areas (MSAs) surrounding Dallas, Houston, New York City, and Phoenix in 2020 and 2021, we extended a previously reported compartmental model accounting for effects of multiple distinct periods of non-pharmaceutical interventions by adding consideration of vaccination and Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) variants Alpha (lineage B.1.1.7) and Delta (lineage B.1.617.2). For each MSA, we found region-specific parameterizations of the model using daily reports of new COVID-19 cases available from January 21, 2020 to October 31, 2021. In the process, we obtained estimates of the relative infectiousness of Alpha and Delta as well as their takeoff times in each MSA (the times at which sustained transmission began). The estimated infectiousness of Alpha ranged from 1.1x to 1.4x that of viral strains circulating in 2020 and early 2021. The estimated relative infectiousness of Delta was higher in all cases, ranging from 1.6x to 2.1x. The estimated Alpha takeoff times ranged from February 1 to February 28, 2021. The estimated Delta takeoff times ranged from June 2 to June 26, 2021. Estimated takeoff times are consistent with genomic surveillance data.

Investigating the diffusion of innovation: A comprehensive study of successive diffusion processes through analysis of search trends, patent records, and academic publications

Adapting to market advances gives organizations a competitive advantage in today's business environment. The anticipation of innovation can be crucial to the competitiveness of an industry. This study analyzes and compares different types of innovation diffusion processes. From a global perspective, it examines the diffusion of interest in an innovation as indicated by a search trend, the diffusion of innovation in patents, and the diffusion of innovation in academic publications. It applies the mathematical modeling of Bass to evaluate the diffusion curves. The findings suggest that the takeoff times in the curves are distinct and sequential, indicating the existence of a series of successive diffusion processes. The diffusion curves of innovation-related search interest reach the takeoff first, followed by the diffusion curves of innovation-related patents and academic publications. The present work contributes to the field by (i) extending the use of innovation diffusion theory to the diffusion of interest in an innovation as indicated by a search trend, the diffusion of innovation in patents, and the diffusion of innovation in academic publications; (ii) demonstrating the differences in diffusion curves and takeoff times; and (iii) indicating the existence of a series of successive diffusion processes.

Using ADS-B Trajectories to Measure How Rapid Exit Taxiways Affect Airport Capacity

The capacity of an airport can be specified with a so-called capacity envelope, which indicates how many take-offs and landings an aerodrome is capable of handling per unit time. In this study, the capacity envelope of an airport is determined on the basis of Automatic Dependent Surveillance-Broadcast aircraft trajectories obtained via the Opensky Network. Trajectories are classified as departures and arrivals by using rule-based algorithms. Subsequently, the time of landing or take-off is determined for all these flight movements. Since some of the trajectories used in this study are not entirely covered near the ground, an XGboost model is used to improve the determination of the take-off and landing times. In a final step, the capacity envelope is determined. To this end, the number of take-offs and landings operated at an airport within 15-minute intervals are counted first. Then, the 92.5th percentile of departures is computed for all observed arrival counts. Finally, a concave, non-increasing piecewise-linear function is fitted to these quantile values. The method introduced in this study is subsequently applied to Lisbon Airport in order to evaluate if and how the construction of an additional rapid exit taxiway has affected its capacity. The results suggest that Lisbon Airport benefits from this rapid exit taxiway. Indeed, especially when the airport handles a high number of landings, the additional rapid exit taxiway appears to allow for a slightly higher number of departures.

Predicting Time to Take-Off in a Countermovement Jump for Maximal Quickness From Upright and Squat Starting Positions

A countermovement jump (CMJ) is common in sport and often time-constrained. Little is known about contributors to quickness in jumps. This study examined effective predictors of time to take-off and effects of the starting position on reaction time and take-off time in a countermovement jump performed for quickness from upright and squat positions. Forty-nine collegiate athletes performed CMJs for quickness from upright and squatting starting positions to 75% of their maximal jump height. Several variables were calculated from the kinetic data related to jump performance. Correlation and multiple regression were used to determine variables related and predictive of time to take-off under both conditions. Paired t-tests evaluated differences in reaction and take-off times between conditions. In the upright condition, an increasing rate of force development and force, and decreasing time variables, impulses, and countermovement depth were associated with shorter time to take-off. The time to take-off prediction included rates of force development, force, time, and impulse. In the squat condition, shorter time to take-off was associated with lesser time variables, eccentric impulse, force at the end of the eccentric phase, and countermovement depth, and a greater rate of force development, concentric impulse, peak power, peak force, and reaction time. The time to take-off prediction equation included time to the bottom of the countermovement, time to peak force, and peak power. Reaction and take-off times were longer in the upright condition. Quick jump efficiency may be improved by strategies to increase maximum strength and the eccentric rate of force development while decreasing countermovement depth and time to bottom.

Multi-Agent Path Finding in Unmanned Aircraft System Traffic Management With Scheduling and Speed Variation

The development of an unmanned aircraft system (UAS) traffic management (UTM) system for the safe integration of unmanned aerial vehicles (UAVs) requires pre-flight conflict detection and resolution (CDR) methods to provide collision-free flight paths for all UAVs before takeoff. A popular solution consists in adapting multi-agent path finding (MAPF) techniques. However, standard MAPF solvers consider only a fixed takeoff time and fixed uniform speed for each UAV flight path, which can lead to inefficiencies in the resolution of instances. Therefore, in this article, we propose incorporating scheduling elements into MAPF solvers, which allows us to adjust the takeoff times and speeds of each UAV to solve conflicts. We introduce two time-related resolution techniques: 1) takeoff scheduling, whereby the start time of a UAV agent is delayed, and 2) speed adjustment, wherein the speed of a UAV agent is decreased over a segment on its flight path. Importantly, we present a distinction of conflict types, which enables us to combine replanning resolution to the aforementioned temporal resolution techniques. We evaluate our proposed approaches on a realistic, high-density UAV delivery scenario in Tokyo, Japan. We show that the combination of takeoff scheduling, replanning, and speed-adjustment resolution techniques improves the efficiency of route planning by reducing the average delay per flight path and the number of rejected flight paths.

Data-Driven Simulation for Evaluating the Impact of Lower Arrival Aircraft Separation on Available Airspace and Runway Capacity at Tokyo International Airport

Although the application of new wake turbulence categories, the so-called “RECAT (wake turbulence category re-categorization)”, will realize lower aircraft separation minima and directly increase runway throughput, the impacts of increasing arrival traffic on the surrounding airspace and arrival traffic flow as a whole have not yet been discussed. This paper proposes a data-driven simulation approach and evaluates the effectiveness of the lower aircraft separation in the arrival traffic at the target airport. The maximum runway capacity was clarified using statistics on aircraft types, stochastic distributions of inter-aircraft time and runway occupancy time, and the levels of the automation systems that supported air traffic controllers’ separation work. Based on the estimated available runway capacity, simulation models were proposed by analyzing actual radar track and flight plan data during the 6 months between September 2019 and February 2020, under actual operational constraints and weather conditions. The simulation results showed that the application of RECAT would reduce vectoring time in the terminal area by 7% to 10% under the current airspace and runway capacity when following a first-come first-served arrival sequence. In addition, increasing airspace capacity by 10% in the terminal area could dramatically reduce en-route and takeoff delay times while keeping vectoring time the same as under the current operation in the terminal area. These findings clarified that applying RECAT would contribute to mitigating air traffic congestion close to the airport, and to reducing delay times in arrival traffic as a whole while increasing runway throughput. The simulation results demonstrated the relevance of the theoretical results given by queue-based approaches in the authors’ past studies.

Ground-level aircraft operations as a measure of sustainable airport efficiency: A weight-restricted DEA approach

Ground-level aircraft operations and landing and take-off cycle account for the vast majority of an airport’s total emission. Among other factors, planning skills are critical in minimizing the emissions produced and fuel burn through reducing taxi times during landing and take-off operations. This study examines the sustainable efficiencies of busiest European airports considering their success in reducing emissions during landing and take-off cycles and argues (i) emission per landing and take-off cycle is a good proxy for ground-level aircraft operation planning skills and provides more practical results than the total amount of annual emission, (ii) weight restriction procedure is necessary in Data Envelopment Analysis applications to ensure furnishing the impact of emission criteria on overall efficiency. A weight-restricted Data Envelopment Analysis model was constructed, and both physical and sustainable efficiencies of each airport were examined during nine years between 2010 and 2018. A combinative Analytic Hierarchy Process – Criteria Importance Through Intercriteria Correlation approach was used to define criteria weights, and a new modified approach was proposed and used to include these weights in Data Envelopment Analysis. Findings proved the necessity of weight restriction when one would examine the impact of emissions produced on sustainable airport efficiency. The Malmquist Productivity Index showed a great shift in physical output production; however, improvements to reduce landing and take-off cycle times have lagged behind the shift in physical output production.

Efficiency and Fairness in Unmanned Air Traffic Flow Management

As the demand for Unmanned Aircraft Systems (UAS) operations increases, UAS Traffic Flow Management (UTFM) initiatives are needed to mitigate congestion, and to ensure safety and efficiency. Congestion mitigation can be achieved by assigning airborne delays (through speed changes or path stretches) or ground delays (holds relative to the desired takeoff times) to aircraft. While the assignment of such delays may increase system efficiency, individual aircraft operators may be unfairly impacted. Dynamic traffic demand, variability in aircraft operator preferences, and differences in the market share of operators complicate the issue of fairness in UTFM. Our work considers the fairness of delay assignment in the context of UTFM. To this end, we formulate the UTFM problem with fairness and show through computational experiments that significant improvements in fairness can be attained at little cost to system efficiency. We demonstrate that when operators are not aligned in how they perceive or value fairness, there is a decrease in the overall fairness of the solution. We find that fairness decreases as the air-ground delay cost ratio increases and that it improves when the operator with dominant market share has a weak preference for the fairness of its allocated delays. Finally, we implemented UTFM in a rolling-horizon setting with dynamic traffic demand, and find that efficiency is adversely impacted. However, the impact on fairness is varied and depends on the metric used.

Analysis of Risk-Based Operational Bird Strike Prevention

Bird strike prevention in civil aviation has traditionally focused on the airport perimeter. Since the risk of especially damaging bird strikes outside the airport boundaries is rising, this paper investigates the safety potential of operational bird strike prevention involving pilots and controllers. In such a concept, controllers would be equipped with a bird strike advisory system, allowing them to delay departures which are most vulnerable to the consequences of bird strikes in case of high bird strike risk. An initial study has shown the strong potential of the concept to prevent bird strikes in case of perfect bird movement prediction. This paper takes the research to the next level by taking into account the limited predictability of bird tracks. As such, the collision avoidance algorithm is extended to a bird strike risk algorithm. The risk of bird strikes is calculated for birds expected to cross the extended runway center line and to cause aircraft damage upon impact. By specifically targeting these birds and excluding birds lingering on the runway which are taken care of by the local wildlife control, capacity reductions should be limited, and the implementation remain feasible. The extrapolation of bird tracks is performed by simple linear regression based on the bird positions known at the intended take-off times. To calculate the probability of collision, uncertainties resulting from variability in bird velocity and track are included. The study demonstrates the necessity to limit alerts to potentially damaging strikes with birds crossing the extended runway center line to keep the imposed delays tolerable for airports operating at their capacity limits. It is shown that predicting bird movements based on simple linear regression without considering individual bird behavior is insufficient to achieve a safety-effect. Hence, in-depth studies of multi-year bird data to develop bird behavior models and reliable predictions are recommended for future research. This is expected to facilitate the implementation of a bird strike advisory system satisfying both safety and capacity aspects.

A Kinematics Comparison of Different Swimming Relay Start Techniques

ABSTRACT In swimming relay races, various start techniques are performed by swimmers, but it remains unclear which technique leads to a better start performance. Therefore, the purpose of the present study was to compare the kinematic characteristics of different relay start techniques with the new starting block Omega OSB11. Eleven international youth swimmers were filmed during 1) no step with parallel feet, 2) no step with separated feet and 3) one-step starts and their centre of mass kinematics calculated with 2D-DLT algorithms. Results indicate that differences between techniques were detected in the spatiotemporal parameters of the block and aerial start phases (e.g., initial and take-off positions, entry height, preparation and changeover times) and in selected parameters of the underwater phase (e.g., emersion time and distance, underwater time and distance). However, no statistical effects were found in 5 m, 10 m and 15 m start times, nor in horizontal take-off velocity, despite an observed trend for the one-step start to be superior to the non-step techniques. These results suggest that differences between relay techniques could rely more on the swimmer’s body posture (angular kinematics) on the block, flight and underwater phases than on the centre of mass linear kinematics.

The Takeoff of Open Source Software: A Signaling Perspective Based on Community Activities

A few open source software (OSS) products exhibit an abrupt and significant increase in downloads. However, the majority of OSS products fail to gain much interest. Identifying early success is important for catalyzing growth in OSS markets. However, previous OSS research has not examined early product success dynamics and assumes adoption to be a continuous process. We propose OSS takeoff in adoptions as a measure of eventual product success. Takeoff is a nonlinear inflection point separating the early development from the growth phase in the product lifecycle. Using arguments from the signaling literature, we propose that community activities send signals about product quality and reduce information asymmetry faced by potential adopters of OSS products. Estimating a Cox proportional hazard model using a large sample of OSS products from SourceForge, we find that takeoff times are significantly associated with signals of quality deficiency and improvement. Further, we find that target audience and product innovativeness moderate this relationship.

Runway scheduling during winter operations

This paper presents an optimization model for the runway scheduling problem under consideration of winter operations. During periods of snowfall, runways have to be intermittently closed in order to clear them from snow, ice, and slush. To support human planners with the resulting complex scheduling tasks, we propose an integrated optimization model to simultaneously plan snow removal for multiple runways and to assign runways as well as take-off and landing times to aircraft. We formulate the model as a mixed-integer linear problem. To improve the computational tractability of our exact approach, we develop pruning rules and valid inequalities. Additionally, we derive initial start solutions heuristically. We validate and benchmark the model with realistic data from a large international airport and compare the results to a practice-based heuristic approach. We also demonstrate the applicability of our algorithm to large-scale aircraft landing instances from the literature. A computational study shows that our solution approach computes runway schedules which cause significantly less aircraft delay cost within a few seconds.

Phase-Specific Predictors of Countermovement Jump Performance That Distinguish Good From Poor Jumpers.

Krzyszkowski, J, Chowning, LD, and Harry, JR. Phase-specific predictors of countermovement jump performance that distinguish good from poor jumpers. J Strength Cond Res 36(5): 1257-1263, 2022-The modified-reactive strength index (RSImod) is commonly examined during the countermovement vertical jump (CMJ) to assess neuromuscular characteristics (i.e., explosiveness, fatigue, adaptation, etc.) of an athlete. However, both phase-specific variables explaining RSImod and corresponding differences between good and poor jumpers are not well understood in trained populations. This study sought to (a) identify predictors of RSImod during the CMJ based on phase-specific temporal and rate of force development (RFD) variables, and (b) identify differences in those predictors between performers with high and low RSImod performances from a sample of collegiate male basketball players (n = 22; 20 ± 2 years; 1.99 ± 0.06 month; 93.8 ± 7.5 kg). Subjects performed 3 maximal effort CMJ trials while ground reaction force data was recorded using 2 force platforms. Phase-specific temporal and RFD variables were calculated and entered into separate stepwise regression models using backward elimination to identify predictors RSImod. Individuals were then categorized into high (n = 11; RSImod = 0.68 ± 0.10) and low (n = 11; RSImod = 0.48 ± 0.04) RSImod groups according to the overall median RSImod (RSImod = 0.55). Independent t-tests (α = 0.05) were conducted and supplemented by Cohen's d effect sizes (d ≥ 1.2, large) to compare groups relative to significant predictors identified by the linear regression models and related variables. The temporal regression model (R2 = 0.530) retained unloading time and concentric time, whereas the RFD regression model (R2 = 0.429) retained unloading RFD and braking RFD. The high RSImod group exhibited significantly greater RSImod scores (d = 2.51, p < 0.001) and jump heights (d = 1.58, p < 0.001), shorter times to takeoff (d = 1.27, p = 0.007) and concentric times (d = 1.51, p = 0.002), and a greater braking RFD (d = 1.41, p = 0.005) than the low RSImod group. Individuals targeting enhanced CMJ performance may consider exploring strategies or interventions to develop quicker unloading and concentric phases and increasing eccentric RFD abilities.

Numerical and experimental analysis of a high innovative hydrofoil

The hydrofoil is a craft where the weight is entirely supported by the lift generated by the submerged part of wings. The particular structure of the craft requires a thorough study of the architecture of the hull, whose structure differs from others high speed vessels since the lift on wing surfaces are transmitted to the hull in limited areas (wing attacks). The authors have developed a research to optimize geometry of hull and wing system on a hydrofoil capable to carry 250 passengers at a speed of 35 knots, operating among Sicilian island. The principal goals of the new hydrofoil concern both the fuel reduction that the improvement of the comfort in terms of seakeeping and levels of acoustic vibrations. In order to reduce the power engines and the acoustic vibrations and to increase the seakeeping during the cruising route and the takeoff, a thorough study of the bow sections (whose profile contributes during this step to exert a thrust which, added to that provided by the wing surfaces, drastically reduces takeoff times) is conducted. Several experimental tests, performed at the towing tank, have allowed to better define the shapes of the hydrofoil and the profile of the wings. An economic assessment was carried out in order to demonstrate that the innovation effort contributes to reducing both construction that operating costs.

Take-off mechanisms in parasitoid wasps.

High-speed video analyses of the natural behaviour of parasitoid wasps revealed three strategies used to launch the insects into the air. Which strategy is the most energy efficient? In Pteromalus puparum, 92% of take-offs by were propelled entirely by movements of the middle and hind legs, which were depressed at their coxo-trochanteral and extended at their femoro-tibial joints. The front legs left the ground first, followed by the hind legs, so that the middle legs provided the final propulsion. Second, in other species of a similar mass, Cotesia glomerata and Leptopilina boulardi, all take-offs were propelled by a mean of 2.8 and 3.8wingbeats, respectively, with little or no contribution from the legs. The first strategy resulted in take-off times that were four times shorter (5 versus 22.8 ms) and take-off velocities that were four times faster (0.8 versus 0.2 m s-1). Calculations from the kinematics indicate that propulsion by the legs was the most energy-efficient strategy, because more energy is put into propulsion of the body, whereas in take-off propelled by repetitive wing movements energy is lost to generating these movements and moving the air. In heavier species such as Netelia testacea and Amblyteles armatorius, take-off was propelled by the combined movements of the middle and hind legs and wingbeats. In A. armatorius, this resulted in the longest mean take-off time of 33.8 ms but an intermediate take-off velocity of 0.4 m s-1 In all three strategies the performance could be explained without invoking energy storage and power amplification mechanisms.

A Queuing Model of the Airport Departure Process

This paper presents an analytical model of the aircraft departure process at an airport. The modeling procedure includes the estimation of unimpeded taxi-out time distributions and the development of a queuing model of the departure runway system based on the transient analysis of D/E/1 queuing systems. The parameters of the runway service process are estimated using operational data. Using the aircraft pushback schedule as input, the model predicts the expected runway schedule and takeoff times. It also estimates the expected taxi-out time, queuing delay, and its variance for each flight in addition to the congestion level of the airport, sizes of the departure runway queues, and the departure throughput. The proposed approach is illustrated using a case study based on Newark Liberty International Airport. The model is trained using data from 2011 and is subsequently used to predict taxi-out times in 2007 and 2010. The predictions are compared with actual data to demonstrate the predictive capabilities of the model.

Lessons from building an automated pre-departure sequencer for airports

Commercial airports are under increasing pressure to comply with the Eurocontrol collaborative decision making (CDM) initiative, to ensure that information is passed between stakeholders, integrate automated decision support or make predictions. These systems can also aid effective operations beyond the airport by communicating scheduling decisions to other relevant parties, such as Eurocontrol, for passing on to downstream airports and enabling overall airspace improvements. One of the major CDM components is aimed at producing the target take-off times and target startup-approval times, i.e. scheduling when the aircraft should push back from the gates and start their engines and when they will take off. For medium-sized airports, a common choice for this is a “pre-departure sequencer” (PDS). In this paper, we describe the design and requirements challenges which arose during our development of a PDS system for medium sized international airports. Firstly, the scheduling problem is highly dynamic and event driven. Secondly, it is important to end-users that the system be predictable and, as far as possible, transparent in its operation, with decisions that can be explained. Thirdly, users can override decisions, and this information has to be taken into account. Finally, it is important that the system is as fair as possible for all users of the airport, and the interpretation of this is considered here. Together, these factors have influenced the design of the PDS system which has been built to work within an existing large system which is being used at many airports.

Influence Of Approach And Arm Swing On Takeoff Velocity In Swimming Relay Exchanges.

Exchanges are crucial in relay swim race performance. Previous research has partially supported an advantage for a start using a one or two step-up approach (1ST and 2ST) with arm swing to add impulse. However, this research has been limited and, to date, no studies have reported these effects on relay exchanges for intercollegiate female swimmers. PURPOSE: To quantify and compare takeoff impulses and velocities by swimmers when employing no step (NST), 1ST, and 2ST relay exchange techniques. METHODS: Twelve intercollegiate female swimmers executed NST, 1ST, and 2ST exchanges on a custom starting platform with a mounted force plate positioned identically to a standard starting block. Data from the plate were collected at 400 Hz. Time of impulse (tIMP) was calculated for each trial. Forces in the force plate frame of reference were projected into the world frame of reference using the angle between the plate’s surface and true horizontal. Time-series force data were integrated over tIMP to calculate starting impulses in the forward and upward directions. These were divided by swimmer mass to compute the components of takeoff velocity (vHOR and vVERT). Paired t-tests were used to compare means for takeoff velocities and times of impulse for the three relay starts (α = 0.05). RESULTS: NST, 1ST, and 2ST starts had mean vHOR of 3.33 ± 0.20, 3.42 ± 0.30, and 3.34 ± 0.24 m/s respectively, all statistically equivalent. Values for vVERT were 0.31 ± 0.24, 0.38 ± 0.30, and 0.26 ± 0.28 m/s respectively, with 1ST greater than 2ST (p = .02). Values for tIMP were 1.14 ± 0.15, 1.22 ± 0.17, and 1.35 ± 0.23 s for NST, 1ST, and 2ST respectively, and were statistically greater from technique to technique (p < .03, p < .03) CONCLUSIONS: No advantage for vHOR existed between techniques, but the time of impulse grew from technique to technique. Therefore, the average force of impulse decreased from technique to technique. There may be limitations in 1ST and 2ST techniques on the generation of horizontal force due to foot placement. Achieving bigger horizontal forces with increased times would yield bigger horizontal takeoff velocities. Future research should investigate ways to achieve this, and examine other starting techniques that may combine bigger forces with increased time of impulse.

Interstitial gas effect on vibrated granular columns.

Vibrated granular materials have been intensively used to investigate particle segregation, convection, and heaping. We report on the behavior of a column of heavy grains bouncing on an oscillating solid surface. Measurements indicate that, for weak effects of the interstitial gas, the temporal variations of the pressure at the base of the column are satisfactorily described by considering that the column, despite the observed dilation, behaves like a porous solid. In addition, direct observation of the column dynamics shows that the grains of the upper and lower surfaces are in free fall in the gravitational field and that the dilation is due to a small delay between their takeoff times.