As an engineer, how do you measure success? It depends on the beholder. If the design fulfills its basic function and, by doing so, simply continues to stand, people who mourned the failure of its predecessor and witnessed the suffering of some connected tragedy will be content.

Try to imagine a machine built today that does not involve software in some form. Can you do it? Even a two-piece, hinged metal can opener was likely conceived on a computer screen using a computer-aided design/computer-aided manufacturing program. Since software is pure design by nature, it cannot ‘fail’ in the classical sense. However, flawed design assumptions and a failure of imagination can lead to unintended or even fatal consequences. When short-sighted specifications or requirements reveal undocumented features, software performs exactly as designed — but not as intended. Accidents where nothing fails are called “systems accidents,” a term that was coined by Yale sociologist Charles Perrow in his book “Normal Accidents.” This study examines the circumstances surrounding a systems accident and the unexpected outcomes.

Many educational and research organizations, including NASA, make use of pressure systems to further their work. However, there are serious risks associated with pressure systems when they are not adequately designed, reviewed or constructed. For example, in March 2016, the University of Hawaii experienced a catastrophic pressure vessel failure that severely injured a postdoctoral researcher. This case study’s purpose is to illustrate the importance of thorough hazard assessment and the expert advice of a center Pressure Systems Manager to help researchers work safely in each NASA lab.

On April 21, 2015, an AC-130J, assigned to the 413th Flight Test Squadron at Eglin Air Force Base in Florida, departed controlled flight over water about 41 nautical miles south of the Air Force base. Even before the crew boarded the aircraft, missed red flags, procedural gaps, incomplete predictive data and documentation anomalies raised the stakes of an already rigorous test plan. Once on board and in the midst of executing an aggressive test maneuver, the collective oversights set the stage for an extraordinary in-flight emergency. Further complicated by insufficient instrumentation and human factors, the crew worked as a team to save their own lives, but the aircraft was not so fortunate. The cost of damages totaled $115,600,000, including the total loss of the aircraft.

Just as you begin typing on your keyboard, your phone rings. You lean over to your left to answer the call. As you continue to work on your computer with your phone pressed between your shoulder and ear, the person on the other end of the phone asks you to reference a paper. You reach to your right to access your file folder. If you work in an office environment, this may sound like a typical workday. The constant reaching and leaning may seem harmless, but having a desk set-up that requires this much movement actually equates to poor ergonomics.

In March 2010, a 29-year-old shift nurse left her job in Atlanta, Georgia and headed to her boyfriend’s house. She was driving her 2005 Chevy Cobalt on a two-lane road as she approached a half-mile downhill straightaway. As the road leveled after the straightaway, she approached an area where some rainwater had accumulated. Shortly after encountering this section of roadway, she apparently lost control of her Cobalt as it hydroplaned across the center line.

On Jan. 12, 2015, Washington Metropolitan Area Transit Authority (WMATA) experienced one of its "more serious" train accidents to date, according to the Federal Transit Administration (FTA). At 3:15 p.m. EST, train 302, which was headed southbound on the Yellow Line with about 380 passengers on board, stopped on the tracks after encountering smoke in the tunnel between the L'Enfant Plaza station and the Potomac River Bridge in Washington, D.C. Some passengers started to self-evacuate to escape the smoke, causing the train control center to shut off third rail power until emergency services could evacuate the victims. In total, the accident resulted in one death, 91 injured people and $120,000 in estimated damages.

The Apollo and Skylab Programs each suffered major setbacks and losses. These events, such as the Apollo 1 fire, the Apollo 13 oxygen tank explosion, and the Skylab 1 micrometeoroid shield loss, continue to serve as lessons and reminders to engineers and managers at NASA and in the expanding private spaceflight industry. As the major incidents of these heritage Programs linger in memory, multiple lesser known crises were averted during the 21 missions that utilized the Apollo spacecraft. During Apollo 10 and Skylab 4, crews suffered from human factors related incidents that were remedied by engineered redundancies and excellent operational knowledge of the spacecraft.

In an extraordinary display of international cooperation during the height of the Cold War between the United States and former Soviet Union, television viewers around the globe tuned in July 17, 1975 to witness Apollo-Soyuz Test Project (ASTP) astronauts and cosmonauts shaking hands between their docked, orbiting spacecraft. Following two days of joint experiments, shared meals and press conferences, the Soyuz crew undocked their spacecraft and landed in Russia on July 21. The Apollo crew continued on-board experiments until their July 24 re-entry. During descent, the crew did not activate the Apollo’s Earth Landing System (ELS) at the correct altitude. As a result, toxic propellant fumes entered the Command Module (CM) through open cabin pressurization valves before splashdown, threatening the lives of America’s first orbital ambassadors.

April 2, 2011, 9:34 a.m. mountain daylight time (MDT), Roswell International Air Center, Roswell, New Mexico: An experimental Gulfstream Aerospace Corporation GVI (G650), N652GD, took off on a planned one-engine-inoperative (idle) (OEI), heavy take-off weight test flight. Test scheduling had been aggressive in order for Gulfstream to obtain Federal Aviation Administration (FAA) type certification for the G650 by the third fiscal quarter of 2011. During the takeoff, the G650 crashed and the four crewmembers aboard died.