Piloted simulation of a ground-based time-control concept for air traffic control

A concept for aiding air traffic controllers in efficiently spacing traffic and meeting scheduled arrival times at a metering fix was developed and tested in a real time simulation. The automation aid, referred to as the ground based 4-D descent advisor (DA), is based on accurate models of aircraft performance and weather conditions. The DA generates suggested clearances, including both top-of-descent-point and speed-profile data, for one or more aircraft in order to achieve specific time or distance separation objectives. The DA algorithm is used by the air traffic controller to resolve conflicts and issue advisories to arrival aircraft. A joint simulation was conducted using a piloted simulator and an advanced concept air traffic control simulation to study the acceptability and accuracy of the DA automation aid from both the pilot's and the air traffic controller's perspectives. The results of the piloted simulation are examined. In the piloted simulation, airline crews executed controller issued descent advisories along standard curved path arrival routes, and were able to achieve an arrival time precision of + or - 20 sec at the metering fix. An analysis of errors generated in turns resulted in further enhancements of the algorithm to improve the predictive accuracy. Evaluations by pilots indicate general support for the concept and provide specific recommendations for improvement

Recessions and the Cost of Job Loss

We develop new evidence on the cumulative earnings losses associated with job displacement, drawing on longitudinal Social Security records for U.S. workers from 1974 to 2008. In present value terms, men lose an average of 1.4 years of pre-displacement earnings if displaced in mass-layoff events that occur when the national unemployment rate is below 6 percent. They lose a staggering 2.8 years of pre-displacement earnings if displaced when the unemployment rate exceeds 8 percent. These results reflect discounting at a 5% annual rate over 20 years after displacement. We also document large cyclical movements in the incidence of job loss and job displacement and present evidence on how worker anxieties about job loss, wage cuts and job opportunities respond to contemporaneous economic conditions. Finally, we confront leading models of unemployment fluctuations with evidence on the present value earnings losses associated with job displacement. The model of Mortensen and Pissarides (1994) extended to include search on the job generates present value losses only one-fourth as large as observed losses. Moreover, present value losses in the model vary little with aggregate conditions at the time of displacement, unlike the pattern in the data.

Simulator evaluation of the final approach spacing tool

The design and simulator evaluation of an automation tool for assisting terminal radar approach controllers in sequencing and spacing traffic onto the final approach course is described. The automation tool, referred to as the Final Approach Spacing Tool (FAST), displays speed and heading advisories for arrivals as well as sequencing information on the controller's radar display. The main functional elements of FAST are a scheduler that schedules and sequences the traffic, a 4-D trajectory synthesizer that generates the advisories, and a graphical interface that displays the information to the controller. FAST was implemented on a high performance workstation. It can be operated as a stand-alone in the Terminal Radar Approach Control (TRACON) Facility or as an element of a system integrated with automation tools in the Air Route Traffic Control Center (ARTCC). FAST was evaluated by experienced TRACON controllers in a real-time air traffic control simulation. Simulation results show that FAST significantly reduced controller workload and demonstrated a potential for an increase in landing rate

Entry, Pricing and Product Design in an Initially Monopolized Market

We analyze entry, pricing and product design in a model with differentiated products. Under plausible conditions, entry into an initially monopolized market leads to higher prices for some, possibly all, consumers. Entry can induce a misallocation of goods to consumers, segment the market in a way that transfers surplus to producers and undermine aggressive pricing by the incumbent. Post entry, firms have strong incentives to modify product designs so as to raise price by strengthening market segmentation. Firms may also forego socially beneficial product improvements in the post-entry equilibrium, because they intensify price competition too much. Multi-product monopoly can lead to better design incentives than the non-cooperative pricing that prevails under competition.

Quantum metrology with Bose-Einstein condensates

We show how a generalized quantum metrology protocol can be implemented in a two-mode Bose-Einstein condensate of n atoms, achieving a sensitivity that scales better than 1/n and approaches 1/n^(3/2) for appropriate design of the condensate

Economic Perspectives on Software Design: PC Operating Systems and Platforms

Improvements in the software that provides hardware management, user interface and platform functions have played a central role in the growth and transformation of the personal computer (PC) industry. Several forces shape the design of these 'operating system' products and propel their evolution over time, including: A. The need to efficiently manage the interacting components of PC systems so as to keep pace with rapid advances in computer technologies the development of applications software. B. The need to maintain compatibility with existing applications while preserving the flexibility to incorporate additional functions that support new applications. C. The desire to economize on customer support costs and assign clear responsibility for making the interacting components of the PC work together. D. The desire to bundle multiple software features into a single package so as to more effectively meet the demand for complementary applications or reduce the diversity in product valuations among consumers. We analyze these forces and the factors that determine whether and when new features and functions are included in commercial operating system products. We also explain how this integration and bundling spurs growth in the PC industry and fosters innovation.