Extra Flight Research Articles

Adaptive Collision Avoidance for Multiple UAVs in Urban Environments

The increasing number of unmanned aerial vehicles (UAVs) in low-altitude airspace is seriously threatening the safety of the urban environment. This paper proposes an adaptive collision avoidance method for multiple UAVs (mUAVs), aiming to provide a safe guidance for UAVs at risk of collision. The proposed method is formulated as a two−layer resolution framework with the considerations of speed adjustment and rerouting strategies. The first layer is established as a deep reinforcement learning (DRL) model with a continuous state space and action space that adaptively selects the most suitable resolution strategy for UAV pairs. The second layer is developed as a collaborative mUAV collision avoidance model, which combines a three-dimensional conflict detection and conflict resolution pool to perform resolution. To train the DRL model, in this paper, a deep deterministic policy gradient (DDPG) algorithm is introduced and improved upon. The results demonstrate that the average time required to calculate a strategy is 0.096 s, the success rate reaches 95.03%, and the extra flight distance is 26.8 m, which meets the real-time requirements and provides a reliable reference for human intervention. The proposed method can adapt to various scenarios, e.g., different numbers and positions of UAVs, with interference from random factors. The improved DDPG algorithm can also significantly improve convergence speed and save training time.

Wild goose chase: Geese flee high and far, and with aftereffects from New Year's fireworks

AbstractIn the present Anthropocene, wild animals are globally affected by human activity. Consumer fireworks during New Year (NY) are widely distributed in W‐Europe and cause strong disturbances that are known to incur stress responses in animals. We analyzed GPS tracks of 347 wild migratory geese of four species during eight NYs quantifying the effects of fireworks on individuals. We show that, in parallel with particulate matter increases, during the night of NY geese flew on average 5–16 km further and 40–150 m higher, and more often shifted to new roost sites than on previous nights. This was also true during the 2020–2021 fireworks ban, despite fireworks activity being reduced. Likely to compensate for extra flight costs, most geese moved less and increased their feeding activity in the following days. Our findings indicate negative effects of NY fireworks on wild birds beyond the previously demonstrated immediate response.

Multi-Aircraft Flight Conflict Resolution and Trajectory Recovery Scheme Based on Mixed Integer Linear Programming and Geometric Rules

A conflict resolution and trajectory recovery scheme based on heading angle change (HAC) is proposed to solve mid-term conflict between multi-aircraft cruising in a shared airspace. Flight conflict resolution has always been regarded as one of the most important responsibilities of air traffic controllers (ATCOs). The proposed conflict resolution scheme can be applied to decision support tools to assist ATCOs in making decisions. The goals of reducing the possibility of human error and increasing the efficiency of airspace operations can be achieved. Firstly, the flight conflict problem is modeled as a class of optimal control problem. Secondly, the optimal solution can be obtained by mixed integer linear programming (MILP) method based on HAC strategy. Thirdly, a trajectory recovery method based on geometric rules is proposed. It can be found through simulated experiment that the extra flight distance and delay adopting the designed scheme is smaller than the compared method.

Impact of COVID-19 on Job Satisfaction: The Case of Military and Airline Pilots

ABSTRACT Objective To investigate how the COVID-19 pandemic has affected the military and airline pilots’ Job Satisfaction (JS), and identify important contributory factors to support the development of future mitigating strategies. Background The aviation industry has undergone a series of devastating changes since the onset of the COVID-19 pandemic. Nonetheless, the implications of the pandemic on pilots’ JS are unknown. Methods Quantitative JS measurements were taken from 203 European and Middle Eastern pilots, during the pandemic (March, 2021), using the shortened Job Descriptive Index and Job In General validated scales. Follow-up semi-structured interviews (April 2021) were conducted with 16 participants to establish pre-pandemic JS levels and identify the degree of change due to COVID-19. Results Significant JS differences (p < .001) were observed between military and airline pilots; the former having higher levels. Qualitative findings revealed that airline pilots’ levels decreased due to factors such as job security, pay cuts, opportunities for promotion and skill-fade concerns. Military pilots experienced an increased JS, as state-funded organizations were not substantially affected by COVID-19, which led to a feeling of appreciation and thankfulness. Conclusion COVID-19 has caused a major disruption to JS of military and airline pilots. Suggested mitigation measures for the civil aviation sector comprised effective communication between pilots and managers to reduce the pandemic-induced job uncertainty. Solutions such as extra flight simulator sorties were recommended to tackle the skill-fade effect.

Autonomous planning of optimal four-dimensional trajectory for real-time en-route airspace operation with solution space visualisation

One of the challenges in applying autonomous operation-based conflict detection and resolution (CD&R) techniques to practice is their functional completeness, such as the ability to simultaneously consider three-dimensional (3D) scenarios, controlled time of arrival, restricted areas, trajectory recovery, and multi-stakeholder performance preferences. Besides, the effective interaction between controllers, pilots and autonomous operating system can better support the CD&R to work in practice, where humans are able to intuitively understand the rationale for solutions given by automatic decision-making tools. To bridge the gap, a novel operational framework for four-dimensional (4D) trajectory conflict management in the context of free route airspace is proposed. Airspace discretisation based on a 3D grid is used to facilitate the consideration of restricted areas and to balance calculation speed and optimal effect. The core of this framework is a two-stage real-time autonomous 4D trajectory planning method in a restricted en-route sector with multiple flight levels enhanced by solution space visualisation. Stage one is a trajectory pre-planning model based on a visibility graph and the Dijkstra algorithm considering the conflict between aircraft and emerging restricted areas. Stage two is a real-time conflict-free and fuel-optimal 4D trajectory re-planning model. The space–time prism is employed to enable the planned trajectory to meet the controlled time of arrival and trajectory recovery requirements, where the performance preferences of both the air traffic management and airspace users are taken into account. The reachable solution space representation is applied to realise the solution space visualisation that has the potential to support the human–machine interaction and air–ground coordination. A simulation scenario is established to validate the effectiveness, efficiency, stability, and timeliness of the proposed method. Results show that in an artificial en-route sector, the average extra flight distance, average flight delay, average extra fuel consumption, and average computing time for conflict resolution were less than 0.41 km, 2.1 s, 1.5 kg, and 0.08 s in the saturated scenario, respectively, and the domino effect of the flight conflict did not show a significant rise with the increase of traffic density, which verified that the proposed autonomous trajectory operation methodology is a promising approach to facilitate autonomous air traffic management in the future.

Body and Wing Allometries Reveal Flight-Fecundity Tradeoff in Response to Larval Provisioning in Osmia lignaria (Hymenoptera: Megachilidae).

Variation in body size has important implications for physical performance and fitness. For insects, adult size and morphology are determined by larval growth and metamorphosis. Female blue orchard bees, Osmia lignaria, (Say) provision a finite quantity of food to their offspring. In this study, we asked how provision-dependent variation in size changes adult morphology. We performed a diet manipulation in which some larvae were starved in the final instar and some were given unlimited food. We examined the consequences on adult morphology in two ways. First, allometric relationships between major body regions (head, thorax, abdomen) and total body mass were measured to determine relative growth of these structures. Second, morphometrics that are critical for flight (wing area, wing loading, and extra flight power index) were quantified. Head and thorax mass had hyperallometric relationships with body size, indicating these parts become disproportionately large in adults when larvae are given copious provisions. However, abdominal mass and wing area increased hypoallometrically with body size. Thus, large adults had disproportionately lighter abdomens and smaller wing areas than smaller adults. Though both males and females followed these general patterns, allometric patterns were affected by sex. For flight metrics, small adults had reduced wing loading and an increased extra flight power index. These results suggest that diet quantity alters development in ways that affect the morphometric trait relationships in adult O. lignaria and may lead to functional differences in performance.

PERAMALAN JUMLAH PENUMPANG PESAWAT DI BANDARA INTERNASIONAL AHMAD YANI DENGAN METODE HOLT WINTER’S EXPONENTIAL SMOOTHING DAN METODE EXPONENTIAL EMOOTHING EVENT BASED

Forecasting the number of airplane passengers can be a consideration for the airline at Ahmad Yani International Airport related with addition of extra flight. The number of airplane passengers can be influenced by certain seasonal or special events. The seasonal influences can be known through historical data patterns and if there is a seasonal pattern, the Holt Winter’s Exponential Smoothing method can be used. Exponential Smoothing Event Based (ESEB) forecasting method can be use to see the special events that effect the number of airplane passengers at Ahmad Yani International Airport. After compared, the Holt Winter’s Exponential Smoothing method is a better method of forecasting the number of airplane passengers at Ahmad Yani International Airport because it has a smaller error value, namely the MSE value and the MAPE value than the Exponential Smoothing Event Based (ESEB)method. The MAPE and MSE values be produced from the best method each of 5,644139% and 619,998,718 .Keywords : Airplane Passengers, Seasonal Pattern, Special Event, Exponential Smoothing Event Based , Holt Winter’s Exponential Smoothing.

Pengkajian Permohonan Izin Terbang (Flight Approval) Untuk Penambahan Penerbangan (Extra Flightj Rute Dalam Negeri di Bandar Udara Ngurah Rai - Bali

Research about Flight Approval for Extra Flight Domestic Route in the Ngurah Rai Airport Bali has been done. The aim of research is to kncnv the difference of the perception behveen the airlines for the mechanism of the implementation flight approval to extra flight in the Ngurah Rai Airport - Bali by the Director General of Aviation Transportation by using the Kruskal Wallis Test method. The results of the research show that there are significant difference perception bet-ween the airlines, but in the principle perception of airline was together positive tawards the process of flight approval in hard copy (physical) was compared through the short message service, the facsimile or the electronics letter (the e-mail/g-mail). As long as period in September 2010 up to March 2011 (7 months), total flight approval to extra flight was 685 and it was increased on the day or the holiday season like at the time of the New Year holiday (in December - in January) and the school child's holiday (in May - in June) on 2010. Keywords: flight approval, extra flight, Kruskal Wallis Test, airlines

Strapdown Airborne Gravimetry Quality Assessment Method Based on Single Survey Line Data: A Study by SGA-WZ02 Gravimeter.

Quality assessment is an important part in the strapdown airborne gravimetry. Root mean square error (RMSE) evaluation method is a classical way to evaluate the gravimetry quality, but classical evaluation methods are preconditioned by extra flight or reference data. Thus, a method, which is able to largely conquer the premises of classical quality assessment methods and can be used in single survey line, has been developed in this paper. According to theoretical analysis, the method chooses the stability of two horizontal attitude angles, horizontal specific force and vertical specific force as the determinants of quality assessment method. The actual data, collected by SGA-WZ02 from 13 flights 21 lines in certain survey, was used to build the model and elaborate the method. To substantiate the performance of the quality assessment model, the model is applied in extra repeat line flights from two surveys. Compared with internal RMSE, standard deviation of assessment residuals are 0.23 mGal and 0.16 mGal in two surveys, which shows that the quality assessment method is reliable and stricter. The extra flights are not necessary by specially arranging the route of flights. The method, summarized from SGA-WZ02, is a feasible approach to assess gravimetry quality using single line data and is also suitable for other strapdown gravimeters.

Insights from stable isotopic tracers on reproductive allocation under stress.

Fecundity is affected by changes in the nutritional and energetic environment, as a result of changes in acquisition, assimilation, or allocation of macro-nutrients and micro-nutrients. Stable isotopes of carbon and nitrogen offer a window into the processes underlying these changes. In insects that feed on nectar as adults, carbon isotopes can be used to trace allocation of carbon to eggs from larval (capital) and adult (income) sources. If adults are fed sugar-water, there is no source of nitrogen from the adult diet. Thus, nitrogen isotopes in eggs reflect fractionation of larval nitrogen due to protein catabolism and anabolism. We subjected adult females of two butterfly species, Speyeria mormonia and Colias eurytheme, to dietary restriction (DR), larval female S. mormonia to DR, and adult female S. mormonia to extra flight. Females subjected to extra flight were previously found to eat more as adults and to have a higher resting metabolic rate. As predicted, significantly less carbon obtained by feeding as adults was incorporated into eggs in both species under DR when adult. Speyeria mormonia eggs contained significantly more carbon derived from adult feeding under DR as larvae and when subjected to extra flight as adult females. Again as predicted, eggs from females of both species subjected to DR when adults were enriched for (15)N, suggesting that increased protein catabolism or anabolism generated additional carbon compounds. Speyeria mormonia eggs from females subjected to DR when larvae or to additional flight as adults were depleted for (15)N. The result for DR of larvae suggests minimization of protein catabolism when protein reserves are relatively scarce. The results for flight were not as predicted, and deserve further exploration. In most cases, isotopic signature in eggs changed with females' age. Eggs were progressively more enriched for the carbon signature of adults, consistent with a two-compartment mixing model for the carbon sources of larvae and adults. Eggs laid across the life of a female were progressively depleted for (15)N, followed by stabilization. This could be due to high total investment in eggs early in life, as the results are consistent with those for other growing animals. Overall, these results indicate shifts in allocation of incoming and stored (capital) carbon in response to various environmental stresses. The results for nitrogen suggest hypotheses to be tested concerning nitrogen metabolism under environmental stress.

Conflict Resolution in Converging Air Traffic Using Trajectory Patterns

A method for conflict detection and resolution based on the parameterization of the aircraft intents is presented. The method is also based on the use of predefined trajectory patterns, which are in fact flight intents; these patterns include standard airline procedures and air traffic control regulations. The conflict resolution problem is formulated as a parametric optimization problem subject to constraints; the optimality criterium is defined so that the deviation from the intended (preferred) trajectories in the lateral profile is minimized. The resolution trajectory patterns take into account changes of the nominal waypoints (vectoring) and changes of the aircraft speeds. The method is applied to the case of multiple conflicts among commercial transport aircraft in converging traffic in the terminal area; different scenarios are considered, which include locked aircraft, that is, aircraft whose trajectories are known and fixed. The conflict detection and resolution algorithm relies on a kinetic trajectory predictor (nonlinear point-mass model with variable mass), which is accurate, flexible, and transparent, and provides the high-fidelity prediction required in the analysis of the demanding terminal area traffic. The cost of the global conflict resolution process is assessed, in terms of extra distance traveled, extra flight time, and extra fuel consumed for each aircraft.

Solving a robust airline crew pairing problem with column generation

In this study, we solve a robust version of the airline crew pairing problem. Our concept of robustness was partially shaped during our discussions with small local airlines in Turkey which may have to add a set of extra flights into their schedule at short notice during operation. Thus, robustness in this case is related to the ability of accommodating these extra flights at the time of operation by disrupting the original plans as minimally as possible. We focus on the crew pairing aspect of robustness and prescribe that the planned crew pairings incorporate a number of predefined recovery solutions for each potential extra flight. These solutions are implemented only if necessary for recovery purposes and involve either inserting an extra flight into an existing pairing or partially swapping the flights in two existing pairings in order to cover an extra flight. The resulting mathematical programming model follows the conventional set covering formulation of the airline crew pairing problem typically solved by column generation with an additional complication. The model includes constraints that depend on the columns due to the robustness consideration and grows not only column-wise but also row-wise as new columns are generated. To solve this difficult model, we propose a row and column generation approach. This approach requires a set of modifications to the multi-label shortest path problem for pricing out new columns (pairings) and various mechanisms to handle the simultaneous increase in the number of rows and columns in the restricted master problem during column generation. We conduct computational experiments on a set of real instances compiled from local airlines in Turkey.

Barriers to movement: Modelling energetic costs of avoiding marine wind farms amongst breeding seabirds

Proposals for wind farms in areas of known importance for breeding seabirds highlight the need to understand the impacts of these structures. Using an energetic modelling approach, we examine the effects of wind farms as barriers to movement on seabirds of differing morphology. Additional costs, expressed in relation to typical daily energetic expenditures, were highest per unit flight for seabirds with high wing loadings, such as cormorants. Taking species-specific differences into account, costs were relatively higher in terns, due to the high daily frequency of foraging flights. For all species, costs of extra flight to avoid a wind farm appear much less than those imposed by low food abundance or adverse weather, although such costs will be additive to these. We conclude that adopting a species-specific approach is essential when assessing the impacts of wind farms on breeding seabird populations, to fully anticipate the effects of avoidance flights.

Robust crew pairing for managing extra flights

This paper discusses a modeling approach to robust crew pairing when a set of extra flights is likely to be added to the regular flight schedule. The set of these possible extra flights is known at the planning stage. We demonstrate that these extra flights may be incorporated into the schedule if necessary by modifying the planned crew pairings appropriately and without delaying or canceling existing flights. To this end, we either identify a pair of crews whose schedules may be (partially) swapped while adding an extra flight into the schedule or show that an extra flight may be inserted into the schedule of a crew without affecting others. We note that deadheading may be necessary in either case. For these two types of solutions, we define the appropriate feasibility rules with respect to the common airline regulations. We then propose two robust mathematical programming models that consider incorporating such solutions into the set of selected pairings while keeping the increase in the crew cost at an acceptable level. The baseline solution for comparison is found by a conventional crew pairing model in the literature which ignores robustness at the planning stage and relies on recovery procedures at the time of operation. We also propose the variations of the two models, where the double counting of the possible solutions across extra flights is prevented. Finally, we conduct computational experiments on a set of data generated from the actual data of an airline company. We solve the crew pairing problem both with the proposed robust models and the conventional model. Our results demonstrate the benefits of the proposed modeling approach and indicate that the proposed robust models provide natural options to recovery without disrupting the existing flights at a relatively small incremental cost, which is visible at the planning stage.

Internalization of airport congestion: A network analysis

The theory developed in this paper, which generalizes the analysis of Brueckner (2002) [Brueckner, J.K., 2002. Airport congestion when carriers have market power. American Economic Review, 1357–1375], establishes a simple rule for the computation of airport congestion tolls, reflecting the internalization of congestion. The analysis shows that the toll paid by a carrier should equal the congestion damage from an extra flight times one minus the carrier's airport flight share. When this flight share is large, most of the congestion created by additional flight is internalized by the carrier, justifying a low toll, and conversely when the flight share is small. The rule is derived within a realistic network structure containing multiple hub airports.

The overredundant spacecraft—A competitive approach to future telecommunication satellites

Present operational space telecommunication systems are based on simultaneous availability of more than one satellite on orbit, mainly a spare satellite in addition to the operational one. Considering the costs associated to the delivery of extra flight models and to extra launchers, the question is asked whether it would not be advantageous to launch a very limited number of “overredundant” spacecraft instead of several standard satellites. The paper gives main conditions of reliability, size and redundancy concept under which an “overredundant” spacecraft could be a competitive approach to future operational systems.