Airline crew scheduling

An airline must cover each flight leg with a full complement of cabin crew in a manner consistent with safety regulations and award requirements. Methods are investigated for solving the set partitioning and covering problem. A test example illustrates the problem and the use of heuristics. The Study Group achieved an understanding of the problem and a plan for further work

Hybrid Tri-Objective Optimization of F-15 Fleet Modernization Scheduling

The F-15 weapons system is vital to the Air Forces efforts to obtain air supremacy during conflict. Originally produced almost 50 years ago, technological advancement through systems modifications is necessary to ensure the Eagles lethality and survivability against next-generation adversarial threats. The F-15 Systems Program Office faces challenges to plan aircraft inductions for five fleet modernization programs. Optimal induction schedules are developed using binary-integer linear programming models. Diverse constraints such as manpower, equipment, modification kit availability, minimum operational flight levels, and integration of scheduled depot maintenance reveal that no feasible schedule exists. Two competing objectives representing the value of fully modernized airframes and the additional workload associated with modifications are explored using the weighted sums method. To enable model solvability, penalties are associated with constraint relaxations with an aggregate penalty term is incorporated into the objective function. Implementing value focused decision analysis techniques, a fleet hierarchy is establishes aircraft precedence for instances having scarce resources shared amongst multiple fighter jets. Sensitivity analysis is employed to examine impacts of various operationally realistic future scenarios

A decision support system for crew planning in passenger transportation using a flexible branch-and-price algorithm

This paper discusses a decision support system for airline and railway crew planning. The system is a state-of-the-art branch-and-price solver that is used for crew scheduling and crew rostering. We briefly discuss the mathematical background of the solver, of which most part is covered in the Operations Research literature. Crew scheduling is crew planning for one or a few days that results in crew duties or pairings, and crew rostering is crew planning for at least one week for individual crew members. Technical issues about the system and its implementation are covered in more detail, as well as several applications. In particular, we focus on

Determining Pilot Manning for Bomber Longevity

In support of US Air Force efforts to conserve resources without sacrificing capability, this research examines the question of whether the 509th Bomb Wing could continue to provide maximum combat capability with fewer assigned pilots. During peacetime, pilot proficiency training comprises the majority of annual flying hours for the small B-2 bomber fleet. Optimal pilot manning will decrease the accumulation of excess wear on the airframes; helping to extend the viable life of the B-2 fleet and preserve the deterrent and combat capabilities that it provides to the United States. The operations and maintenance activity flows for B-2 aircraft and pilots in a notional sustained combat scenario are constructed in an Arena discrete-event simulation model. The model provides the capability to determine optimum manning levels for combat-qualified B-2 pilots across a range of fleet mission capable rates. Determination of actual optimum manning levels is sensitive to duration and probability parameters which are unavailable for use in this work. Notional parameter estimates are used to assess combat mission capability and pilot manning

An Analysis of Robust Workforce Scheduling Models for a Nurse Rostering Problem

Disruptions impacting workforce schedules can be costly. A 1999 study of the United Kingdom\u27s National Health Service estimated that as much as 4% of the total resources spent on staffing were lost to schedule disruptions like absenteeism. Although disruptions can not be eliminated, workforce schedules can be improved to be more responsive to disruptions. One key area of study that has expanded over the past few years is the application of traditional scheduling techniques to re-rostering problems. These efforts have provided methods for responding to schedule disruptions, but typically require deviations to the disrupted schedule. This thesis examines five workforce scheduling models designed for a nurse rostering problem. Each model is designed to produce a robust workforce schedule that remains valid in the midst of disruptions and requires no schedule deviations. Each model is evaluated based on the number of disruptions it can receive before becoming invalid. Nonparametric statistical analysis is used to analyze the disruption data for each model and determine which workforce scheduling model produces the most robust schedule. The results of this research indicate that additional manpower must be applied to the correct skill sets in order to produce robust workforce schedules. Furthermore, workforce managers can consider leaving a portion of the workforce unscheduled (or in reserve) to accommodate schedule disruptions

Algebra of Tankers

The Air Force\u27s aerial refueling tanker aircraft provide essential support for deployment and employment of combat and combat support aircraft, by extending their endurance and enhancing fighting efficiency. As the lead command for air refuelers, Air Mobility Command (AMC) must frequently examine the capability of current and proposed tanker fleets to meet mission requirements due to limited tanker resources. Analysts in AMC primarily use the Combined Mating and Ranging Plans System to provide actual tanker/receiver aircraft schedules and flight plans that take into account numerous system constraints. However, this tool can take weeks to run. Even recently developed quick look tools, aimed at optimization of the fleet, can take 1/2 hour or more. Additionally, most of these more recent studies and tools assess the feasibility of deployments. Less attention has been given to the employment phase of missions. AMC lacks a quick look tool to quickly perform rough cut capacity analysis for tanker use and assess the feasibility of proposed employment of tankers. To develop a feasibility quick look tool, the basic formulae for computing tankers missions must be understood. While the airlift community has defined million ton miles per day as their keystone metric, the tanker community -- concerned with being on time, on target, with fuel -- lacks such a definitive metric. This thesis describes fundamental algebraic relations that characterize employment of air refueling aircraft, employing rough cut capacity planning to determine feasibility of tanker employment with a given amount of resources. The Tanker Employment Model provides AMC with an efficient tool for quickly assessing tanker employment capabilities

Mathematical Programming Model for Fighter Training Squadron Pilot Scheduling

The United States Air Force fighter training squadrons build weekly schedules using a long and tedious process. Very little of this process is automated and optimality of any kind is nearly impossible. Schedules are built to a feasible condition only to be changed with consideration of Wing level requirements. Weekly flying schedules are restricted by requirements for crew rest, days since a pilot\u27s last sortie, sorties in the last 30 days, and sorties in the last 90 days. By providing a scheduling model to the pilot charged with creating the schedule, valuable pilot hours could be spent in the cockpit, simulator, or other required duty. This research effort presents a mathematical programming (MP) approach to the fighter squadron pilot training scheduling problem. The methodology presented is based on binary variables that will provide integer solutions to every feasible set of inputs. A simulator heuristic developed specifically for this problem assigns pilots to simulator sorties based on the feasible solutions obtained from two different formulation and solving approaches. One approach assigns training mission sorties and duties for the entire week, while the other approach breaks the week into ten successive sub-problems. The model constructs two feasible schedules in approximately 2.5 minutes

Optimization Model for an Airline Crew Rostering Problem: Case of Garuda Indonesia

This paper discusses the cockpit crew rostering problem at Garuda Indonesia, taking into account a number of internal cockpit crew labor regulations. These internal labor regulations are in general more restrictive at Garuda Indonesia than at other airlines, so that modeling the cockpit crew rostering problem for Garuda Indonesia is challenging. We have derived mathematical expressions for the cockpit crew labor regulations and some technical matters. We model a non-linear integer programming for the rostering problem, using the average relative deviation of total flight time to the ideal flight time as the objective function. The optimization model have been tested for all classes of cockpit crews of Garuda Indonesia, using a simulated annealing method for solving the problem. We obtained satisfactory rosters for all crew members in a short amount of computing time. This shows that the optimization problem is well-defined

Army-NASA aircrew/aircraft integration program (A3I) software detailed design document, phase 3

The capabilities and design approach of the MIDAS (Man-machine Integration Design and Analysis System) computer-aided engineering (CAE) workstation under development by the Army-NASA Aircrew/Aircraft Integration Program is detailed. This workstation uses graphic, symbolic, and numeric prototyping tools and human performance models as part of an integrated design/analysis environment for crewstation human engineering. Developed incrementally, the requirements and design for Phase 3 (Dec. 1987 to Jun. 1989) are described. Software tools/models developed or significantly modified during this phase included: an interactive 3-D graphic cockpit design editor; multiple-perspective graphic views to observe simulation scenarios; symbolic methods to model the mission decomposition, equipment functions, pilot tasking and loading, as well as control the simulation; a 3-D dynamic anthropometric model; an intermachine communications package; and a training assessment component. These components were successfully used during Phase 3 to demonstrate the complex interactions and human engineering findings involved with a proposed cockpit communications design change in a simulated AH-64A Apache helicopter/mission that maps to empirical data from a similar study and AH-1 Cobra flight test