Photographers gather to take pictures of pilot Andre Borschberg (C) ahead of the take off of Solar Impulse 2-a solar powered plane- in Nanjing, China, May 31, 2015. The world's largest solar-powered airplane, Solar Impulse 2, took off from eastern China's Nanjing on Sunday to continue its round-the-world voyage. The Swiss-made plane left Nanjing's Lukou International Airport at 2:39 in the early morning, with former fighter pilot Borschberg at the controls alone for the entire 8,200-kilometer flight from Nanjing to Hawaii, the toughest leg of its marathon adventure. (Photo by Reuters/Solar Impulse)

Aerial acrobat Schindler, notorious for his foolhardy stunts, practising one of his tricks listing out of the vertical, from a Klemp plane piloted by Richard Perlia. (Photo by General Photographic Agency/Getty Images). Circa 1927

The Breitling DC-3, HB-IRJ, plane fly escorted by Italian Air Force's aerobatic demonstration team, the Frecce Tricolori, during the last stage of its world tour two days ahead of the International Sion Air Show, in Sion, Switzerland, 13 September 2017. From March to September 2017, the Breitling DC-3 from 1940 has done a grand world tour in several stages, over 28 countries and flies 50000km, an amazing accomplishment for this legendary plane that will be celebrating its 77th birthday. (Photo by Christian Merz/EPA/EFE)

The Jumbo Stay blends into the background at Stockholm Arlanda Airport. If you spot it as your plane rolls along a taxiway, you might notice an aging widebody jet parked by its lonesome self in a secluded part of the airport.

Syrian President Bashar Al Assad watches as Pope John Paul II boards his plane at Damascus airport May 8, 2001 at the end of the Pontiff's four-day visit to Syria.

Family of passengers onboard AirAsia flight QZ8501 react at a waiting area in Juanda International Airport, Surabaya December 28, 2014. Indonesia's air force was searching for the AirAsia plane carrying 162 people that went missing on Sunday after the pilots asked to change course to avoid bad weather during a flight from the Indonesian city of Surabaya to Singapore. The Airbus 320-200 lost contact with Jakarta air traffic control at 6:17 a.m. (23:17 GMT), officials said. (Photo by Reuters/Beawiharta)

Indonesian air force personnel carry the flight data recorder of the ill-fated AirAsia Flight 8501 that crashed in the Java Sea, at airport in Pangkalan Bun, Indonesia, Monday, January 12, 2015. Divers retrieved one black box Monday and located the other from the AirAsia plane that crashed more than two weeks ago, a key development that should help investigators unravel what caused the aircraft to plummet into the Java Sea. (Photo by Achmad Ibrahim/AP Photo)

In this Tuesday, March 17, 2015 photo, a French military plane takes off from the flight deck of the French Navy aircraft carrier Charles de Gaulle in the Persian Gulf. Aircraft aboard the French carrier are flying bombing and reconnaissance missions as part of a U.S.-led coalition targeting Islamic State militants in Iraq. (Photo by Hasan Jamali/AP Photo)