On the Factors that Affect Airline Flight Frequency and Aircraft Size

This paper assesses the determinants of aircraft size and frequency of flights on airline routes by considering market demographics, airport characteristics, airline characteristics and route characteristics. The paper shows that frequency and aircraft size increase with population, income, and runway length. An increase in the proportion of managerial workers in the labor force or the proportion of population below the age of 25 results in greater frequency with the use of small planes. Slot constrained airports and an increase in the number of nearby airports lead to lower flight frequency with the use of smaller planes. Hubs and low cost carriers are associated with larger plane sizes and higher frequency, while regional airline ownership leads to higher frequency and the use of smaller planes. An increase in distance between the endpoints leads to lower frequency with the use of larger planes. As airport delay rises, airlines reduce frequency and use smaller planes, though when airport cancellations rise, flight frequency increases with the use of larger planes. This finding suggests airlines utilize frequency and aircraft size to hedge against flight cancellations.Airline; Frequency; Aircraft size; Markets

Technological Innovation in the Airline Industry: The Impact of Regional Jets

This paper explores the impact of the regional jet (RJ), an important new technological innovation in the airline industry, on service patterns and service quality. The evidence shows that RJs were used to provide service on a large number of new hub-and-spoke (HS) and point-to-point (PP) routes. In addition, they replaced discontinued jet and turboprop service on many HS routes, as well as supplementing continuing jet service on such routes. When replacement or supplementation by RJs occurred, passengers benefited from better service quality via higher flight frequencies. The paper's theoretical analysis predicts that the frequency advantage of RJs over jets, a consequence of their small size, should have led to the emergence of PP service in thin markets where such service was previously uneconomical. However, the evidence contradicts this prediction, showing that markets attracting new PP service by RJs had demographic characteristics similar to those of markets that already had jet PP service or attracted it after 1996.Regional jet; Airlines; Network

Losing access to online distribution platforms cost American Airlines more than $50 million in revenues

Despite airlines’ push to divert travellers towards buying tickets via their own websites, online travel agents still play a very important role. In 2011, American Airlines introduced its own booking system for travel agents, prompting a backlash from traditional distributors who blocked access to their platforms. Volodymyr Bilotkach, Nicholas Rupp and Vivek Pai take a close look at the case, finding that the loss of access cost American Airlines more than $50 million in revenue through reduced ticket sales. They write that such conflicts between airlines and traditional channels may become more common in the future, as airlines continue to try to unbundle their services

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Using PlanetLab for network research: Myths, realities, and best practices

PlanetLab is a research testbed that supports 428 experiments on 276 sites, with 583 nodes in 30 countries. It has lowered the barrier to distributed experimentation in network measurement, peer-to-peer networks, content distribution

A rare delayed presentation of giant vesical calculus: the largest vesical calculus to be reported in a female

Vesical calculi are infrequent in females, and the occurrence of giant vesical calculus is even rarer. We report a case of giant vesical calculus in an elderly female which was undiagnosed and empirically treated for six years for recurrent urinary tract infection. On presentation, it was managed by open cystolithotomy. Upon surgical retrieval, the stone measured 11x7.5x7.4 cm in largest dimensions and weighed 672 gm, which to the best of our knowledge, is the largest vesical calculus to be reported in a female patient. This case highlights the need for adequate evaluation of every case of recurrent urinary tract infection with good imaging. Early diagnosis allows for the management of vesical calculi by minimally invasive endoscopic techniques. If missed, it leads to the formation of giant vesical calculi, which require treatment by a much more invasive open surgical approach

IO-Lite: a unified I/O buffering and caching system

This article presents the design, implementation, and evaluation of IO -Lite, a unified I/O buffering and caching system for general-purpose operating systems. IO-Lite unifies all buffering and caching in the system, to the extent permitted by the hardware. In particular, it allows applications, the interprocess communication system, the file system, the file cache, and the network subsystem to safely and concurrently share a single physical copy of the data. Protection and security are maintained through a combination of access control and read-only sharing. IO-Lite eliminates all copying and multiple buffering of I/O data, and enables various cross-subsystem optimizations. Experiments with a Web server show performance improvements between 40 and 80% on real workloads as a result of IO-Lite

Extensible kernels are leading OS researchers astray

We argue that ongoing research in extensible kernels largely fails to address the real challenges facing the OS community. Instead, these efforts have become entangled in trying to solve the safety problems that extensibility itself introduces into OS design. We propose a pragmatic approach to extensibility, where kernel extensions are used in experimental settings to evaluate and develop OS enhancements for demanding applications. Once developed and well understood, these enhancements are then migrated into the base operating system for production use. This approach obviates the need for guaranteeing safety of kernel extensions, allowing the OS research community to re-focus on the real challenges in OS design and implementation. To provide a concrete example of this approach, we analyze the techniques used in experimental HTTP servers to show how proper application design combined with generic enhancements to operating systems can provide the same benefits without requiring application-specific kernel extensions