Entries by 'Sarah Sheard'

Aircraft Systems: Three Principles for Mitigating Complexity

Systems Engineering No Comments »

By Sarah Sheard
Member of the Technical Staff
Software Solutions Division

This post is the first in a series introducing our research into software and system complexity and its impact in avionics.

Sarah Sheard On July 6, 2013, an Asiana Airlines Boeing 777 airplane flying from Seoul, South Korea, crashed on final approach into San Francisco International airport. While 304 of the 307 passengers and crew members on board survived, almost 200 were injured (10 critically) and three young women died. The National Transportation Safety Board (NTSB) blamed the crash on the pilots, but also said “the complexity of the Boeing 777’s auto throttle and auto flight director—two of the plane’s key systems for controlling flight—contributed to the accident.” In a news report, acting NTSB chairman Christopher Hart stated that “The flight crew over-relied on automated systems that they did not fully understand." The NTSB report on the crash called for “reduced design complexity” and enhanced training on the airplane’s autoflight system, among other remediations. Since complexity is a vague concept, it is important to determine exactly what it means in a particular setting. This blog post describes a research area that the Carnegie Mellon University Software Engineering Institute (SEI) is undertaking to address the complexity of aircraft systems and software.

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The Changing Relationship of Systems and Software in Satellites: A Case Study

Systems Engineering 2 Comments »

By Sarah Sheard
Member of the Technical Staff 
Software Solutions Division

Sarah Sheard The role of software within systems has fundamentally changed over the past 50 years. Software’s role has changed both on mission-critical DoD systems, such as fighter aircraft and surveillance equipment, and on commercial products, such astelephones and cars. Software has become not only the brain of most systems, but the backbone of their functionality. Acquisition processes must acknowledge this new reality and adapt. This blog posting, the second in a series about the relationship of software engineering (SwE) and systems engineering (SysE), shows how software technologies have come to dominate what formerly were hardware-based systems. This posting describes a case study: the story of software on satellites, whose lessons can be applied to many other kinds of software-reliant systems.  

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Needed: Improved Collaboration Between Software and Systems Engineering

Systems Engineering 11 Comments »

By Sarah A. Sheard
Senior Engineer
Software Solutions Division
This post is the first in a series on this topic

Sarah SheardThe Government Accountability Office (GAO) recently reported that acquisition program costs typically run 26 percent over budget, with development costs exceeding initial estimates by 40 percent. Moreover, many programs fail to deliver capabilities when promised, experiencing a 21-month delay on average.  The report attributes the “optimistic assumptions about system requirements, technology, and design maturity [that] play a large part in these failures” to a lack of disciplined systems engineering analysis early in the program. What acquisition managers do not always realize is the importance of focusing on software engineering during the early systems engineering effort. Improving on this collaboration is difficult partly because both disciplines appear in a variety of roles and practices. This post, the first in a series, addresses the interaction between systems and software engineering by identifying the similarities and differences between the two disciplines and describing the benefits both could realize through a more collaborative approach. 

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