Pakistani police stand guard as a Pakistan International Airline plane taxis on a runway in Islamabad on Feb. 8. The national carrier has struggled in recent years with a $3 billion debt. Farooq Naeem/AFP/Getty Images hide caption

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United Airlines planes sit on the tarmac at San Francisco International Airport on July 8, grounded by a computer glitch. Some 3,500 United passengers around the world were delayed. Justin Sullivan/Getty Images hide caption

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The Solar Impulse 2 landed in Hawaii in early July. The team behind the sun-powered airplane says it will be grounded until next spring. Solar Impulse | Revillard | Rezo/Solar Impulse | Revillard | Rezo hide caption

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The tiny town of Sundsvall, Sweden, is home to the world's first airport to land passenger planes by remote control. The cameras used to help the air traffic controllers guide airplanes render details as small as cars pulling into the parking lot from miles away. Rich Preston/NPR hide caption

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NORAD identified the plane that crashed off the coast of Jamaica, after flying for several hours with an unresponsive pilot at the helm, as a Socata TBM-700, similar to this one. Wikimedia Commons hide caption

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Malaysia Airlines had been struggling even before two of its flights were lost this year. Analysts say the national carrier faces either bankruptcy or privatization. Mohd Rasfan/AFP/Getty Images hide caption

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The Solar Impulse, a solar-powered plane, flies over Switzerland. The makers will be journeying across the U.S. this spring, hoping the flight helps challenge assumptions about what solar technology can do. Courtesy of Solar Impulse hide caption

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