Aircraft Flight Plans Research Articles

Predicted Trajectory Accuracy Requirements to Reduce Aviation Impact of Space Launch Operations

Thousands of aircraft flight plans are affected by space launch and reentry operations each year, increasing the distances flown, causing flight delays, and increasing air traffic controllers workload. Due to regulations and procedures, predefined Aircraft Hazard Areas (AHAs) are used to protect aircraft from the risks of space launch and reentry debris, thus constraining the available airspace for other airspace users. While disruptive, there is no less impactful approach at present that adequately protects the flying public. In this paper, we explore the application of trajectory-based operations to evaluate the impact of an AHA on commercial aircraft, with the aim of reducing the number of flights that must be rerouted or rescheduled. This approach relies on precise trajectory predictions to the AHA boundary to determine which flights are expected to clear the AHA before its activation or remain clear of the AHA until after its deactivation. This paper derives the required predicted trajectory accuracy for air traffic automation systems to effectively predict flights impacted by an AHA. The required accuracy is derived based on a model for managing flights relative to the AHA using speed changes alone (as opposed to reroutes or holding) in the context of operational uncertainties like departure time delays and flight characteristics. Additionally, we derived a model to relate scheduling buffers to the AHA activation time, delivery accuracy at the AHA boundary, and AHA violation probability.

Air Traffic Safety Assurance Based on Flight Plan Risk Assessment and Early Warning

This article presents a novel risk assessment method for aircraft flight plans in a four-dimensional trajectory-based operation background. With the increasing air transport volume and airspace demand and during the allocation and modification of flight plans, safety should also be considered in addition to economic benefits and competitiveness. By employing the time geography concept, this article first quantifies the space-time accessibility and estimates the visiting probability of aircraft in the four-dimensional trajectory-based operation context. On this basis, this article studies the method and process to evaluate the conflict risk between one flight plan and a special airspace, the weather-influenced airspace, and another flight plan. This article also proposes the conflict risk alerting strategy. The achievements of the study are expected to provide assistance for air traffic controllers in strategic conflict avoidance and are of great significance in assuring air transport safety.

Vertical flight path segments sets for aircraft flight plan prediction and optimisation

ABSTRACTThe paper presents a method for constructing a set of vertical flight path segments, that would compose an aircraft's vertical flight envelope, by using an aircraft performance model. This method is intended to be used for aircraft flight plan prediction and optimisation algorithms. The goal is to reduce the volume of recurring segment performance computations currently required for flight plan prediction or optimisation. The method presented in this paper applies to a free-flight scenario. The flight-path segments composing the vertical flight envelope belong to one of the unrestricted climb, constant-speed level flight, step-climb and continuous descent segments, performed at the consigned climb, cruise and descent speed schedules and at the consigned air temperature values. The method employs an aircraft model using linear interpolation tables. Nine test scenarios were utilised to assess the performances of the resulting flight envelopes as a function of the number of cruise altitudes and descent flight paths. The set of evaluated performance parameters includes the range of total flight times and still-air flight distances, and the vertical profiles describing the minimum and maximum flight times, and still-air flight distances. The advantages of the proposed method are multiple. First, it eliminates the need for repetitive aircraft performance computations of identical vertical flight plan segments, and provides the means for quick retrieval of the corresponding performance data for use in the construction of a full flight plan. Second, the vertical flight path look-up structure and the vertical flight-path graph describe a set of vertical flight paths that consider an aircraft's and flight plan's configuration parameters and cover its maximum flight envelope. Third, the look-up structure and the graph provide the means for rapid and clear identification of the available options for constructing a flight-plan segment, as well as for detecting the points associated with changes in the flight phases, including climb, cruise, step-climb and descent.

Multi-aircraft Conflict Detection and Resolution Based on Probabilistic Reach Sets

In this brief, a novel scheme to multi-aircraft conflict detection and resolution is introduced. A key feature of the proposed scheme is that uncertainty affecting the aircraft future positions along some look-ahead prediction horizon is accounted for via a probabilistic reachability analysis approach. In particular, ellipsoidal probabilistic reach sets are determined by formulating a chance-constrained optimization problem and solving it via a simulation-based method called scenario approach . Conflict detection is then performed by verifying if the ellipsoidal reach sets of different aircraft intersect. If a conflict is detected, then the aircraft flight plans are redesigned by solving a second-order cone program resting on the approximation of the ellipsoidal reach sets with spheres with constant radius along the look-ahead horizon. A bisection procedure allows one to determine the minimum radius such that the ellipsoidal reach sets of different aircraft along the corresponding new flight plans do not intersect. Some numerical examples are presented to show the efficacy of the proposed scheme.

Online Prediction of Battery Discharge and Estimation of Parasitic Loads for an Electric Aircraft

Predicting whether or not vehicle batteries contain sufficient charge to support operations over the remainder of a given flight plan is critical for electric aircraft. This paper describes an approach for identifying upper and lower uncertainty bounds on predictions that aircraft batteries will continue to meet output power and voltage requirements over the remainder of a flight plan. Battery discharge prediction is considered here in terms of the following components; (i) online battery state of charge estimation; (ii) prediction of future battery power demand as a function of an aircraft flight plan; (iii) online estimation of additional parasitic battery loads; and finally, (iv) estimation of flight plan safety. Substantial uncertainty is considered to be an irremovable part of the battery discharge prediction problem. However, highconfidence estimates of flight plan safety or lack of safety are shown to be generated from even highly uncertain prognostic predictions.

Terminal-Area Aircraft Tracking Using Hybrid Estimation

A bottleneck to the flow of air traffic is in the traffic around airports. Accurate tracking of aircraft movements around airports is important to improve traffic capacity and safety. We propose a hybrid estimation algorithm that uses the knowledge of departure or arrival aircraft flight plans and nominal flight profiles to improve tracking of aircraft movements around airports. The algorithm also provides an accurate estimation of aircraft flight modes that is often used in conflict detection, intent inference, and trajectory prediction algorithms. In the algorithm, we first develop a methodology to model flight mode transitions based on typical aircraft landing profiles, takeoff profiles, and standard flight routes around airports. Based on the model, we derive a conditional mode transition matrix that is dependent (or conditioned) on the continuous state of the aircraft. The aircraft-tracking problem is then solved using a hybrid estimation algorithm. We also present an analytical result that reduces the dimension, and hence the computational cost, of a multivariate integral that arises due to the continuous-state-dependent mode transition matrix. We present two simulation examples to illustrate the performance of our aircraft-tracking algorithm.

New Algorithms for Aircraft Intent Inference and Trajectory Prediction

Aircraft tracking, intent inference, and trajectory predictions are important tools for enhanced capacity in air traffic control operations. In this paper, we propose an algorithm that performs these three tasks accurately. The algorithm uses a hybrid estimation algorithm to estimate the aircraft's state and flight mode. These estimates are combined with knowledge about air traffic control regulations, the aircraft's flight plan, and the environment to infer the pilot's intent. Trajectory predictions are computed as a function of the aircraft's motion (state and mode estimates) and the inferred intent The result is an algorithm that provides, in real-time, accurate intent and trajectory predictions for aircraft. We analyze and test the performance of the proposed algorithm with various scenarios representative of current and future aircraft operations within the National Airspace System.

航空機の経路最適化に関する研究-IV : 最適ルートに平行なルートの経済性評価およびリルーティングの効果について

In this study, economic evaluation of the aircraft routes parallel to the optimum route was performed by the simulations. It was found that compared with the optimum route between San Francisco and Tokyo, the average fuel increases on the parallel routes passing 30, 50 and 100n.m. away from the optimum route were 0.1, 0.2 and 0.7%, respectively. Thus it can be said the parallel routes with 30 and 50n.m. separation distances have almost the same economic advantage as the optimum route. The effectiveness of rerouting (i.e. change of an aircraft's flight plan based on the updated wind forecast while the aircraft is en route) was also investigated by the simulations for New York-Tokyo route and San Francisco-Tokyo route. By executing the rerouting at the beginning of cruising, the fuel was saved by 0.5% on the average (1.3-2.2% at the maximum) and the flight time was shortened by 0.5-0.8% on the average (2.0-3.4% at the maximum), which verified the effectiveness of rerouting.

Time-based air-traffic management using expert systems

A prototype expert system has been developed for the time scheduling of aircraft into the terminal area. The three functions of the air-traffic-control schedule advisor are as follows: First, for each new arrival, it develops an admissible flight plan for that aircraft. Second, as the aircraft progresses through the terminal area, it monitors deviations from the aircraft's flight plan and provides advisories to return the aircraft to its assigned schedule. Third, if major disruptions such as missed approaches occur, it develops a revised plan. The advisor is operational on a Symbolics 3600 and is programmed in MRS (a logic programming language), Lisp, and Fortran.

A Method for Radar Turbulence Detection

A method is described whereby a conventional non-Doppler radar may be used in the measurement and detection of atmospheric turbulence. The technique involves the measurement of the average echo power and the variance of the fluctuation spectrum in each of two separated pulse volumes, and corresponding measure ments of echo power and variance of the detected signals in a channel representing the predetection sum of the signals from those two volumes. It is shown that the variance of the sum channel is the power-weighted sum of the variances in the independent channels plus a term dependent upon the difference in mean radial velocity of the associated pulse volumes. Accordingly, the difference in mean radial velocity can be measured. When the spacing of the sampled volumes is adjusted to represent distance along an aircraft flight plan, the measurement is a measure of the turbulence to be experienced in traversing the space between those volumes. Specific systems for accomplishing the measure ment are discussed.