Empty runways and parked passenger aircraft are seen grounded at Copenhagen Airport, Denmark, Wednesday, March 25, 2020. About 4, 000 employees from the nordic airline company SAS have agreed to have their pay cut down during the COVID-19 coronavirus outbreak. (Photo by Martin Sylvest/Ritzau Scanpix via AP Photo)





Grounded Virgin Australia aircraft are seen parked at Brisbane Airport in Brisbane, Tuesday, April 7, 2020. Brisbane Airport Corporation (BAC) is working with airlines by accommodating up to 100 grounded aircraft free of charge in response to government-mandated travel restrictions that have grounded a significant proportion of Australia's airline fleet because of the Coronavirus (COVID-19). (Photo by Darren England/AAP Image)





Aircrafts are parked on a runway at the airport in Frankfurt, Germany, Sunday, March 15, 2020. Due to the Coronavirus, Lufthansa had to cancel half of its flights. For most people, the new coronavirus causes only mild or moderate symptoms. For some, it can cause more severe illness, especially in older adults and people with existing health problems. (Photo by Michael Probst/AP Photo)





Grounded planes at Birmingham International Airport in England on March 23, 2020. The government are advising that all but essential travel should be avoided as to limit the spread of coronavirus. (Photo by Jacob King/PA Images via Getty Images)





People gather near an Ilyushin IL-76 military cargo plane of the Uzbek Air Force, which transports protective equipment to China hit by the new coronavirus, before the departure from an airport of Tashkent, Uzbekistan on February 12, 2020. (Photo by Mukhammadsharif Mamatkulov/Reuters)





In this June 18 2015 file photo, vapor forms across the wings of an Airbus A380 as it performs a demonstration flight at the Paris Air Show, Le Bourget airport, north of Paris. Airbus sAys it will stop making its costly A380 superjumbo if it can't strike a long-term deal with Emirates airline for a steady supply of the planes. (Photo by Francois Mori/AP Photo)





American Airlines 737 max passenger planes are parked on the tarmac at Tulsa International Airport in Tulsa, Oklahoma, U.S. March 23, 2020. (Photo by Nick Oxford/Reuters)





A Boeing 747 of Asiana Airlines lands at the airport in Frankfurt, Germany, Sunday, March 1, 2020. The aviation industry expects heavy financial losses due to the Covid-19 virus. (Photo by Michael Probst/AP Photo)





An aerobatic team “First Flight” piloting Yak-52 and Yak-54 aircrafts performs during the MAKS-2019 International Aviation and Space Salon in Zhukovsky outside Moscow, Russia, 01 September 2019. The Salon runs from 27 August to 01 September. (Photo by Sergei Ilnitsky/EPA/EFE/Rex Features/Shutterstock)





In this April 9, 2019, file photo a Boeing 737 fuselage, eventually bound for Boeing's production facility in nearby Renton, Wash., sits on a flatcar rail car at a rail yard as a jet flies past overhead in Seattle. (Photo by Elaine Thompson/AP Photo/File)





This undated photo provided by NASA shows SOFIA over the snow-covered Sierra Nevada mountains with its telescope door open during a test flight. The world's largest airborne observatory was supposed to be parked in Seattle this week, so thousands of scientists attending the “Super Bowl of Astronomy” could behold this marvel: a Boeing 747, like this one shown, for example, outfitted with a massive telescope used to study the fundamental mysteries of the universe. (Photo by Jim Ross/NASA via AP Photo)





A plane flies through the “Tribute in Lights” marking the 10th anniversary of the 9/11 attacks in lower Manhattan, New York, U.S., September 10, 2011. (Photo by Eric Thayer/Reuters)





In this March 25, 2020, file photo, an Italian Air Force plane carrying two patients from Italy believed to have COVID-19, lands at Leipzig Airport, Germany. In the rare position of having beds to spare, German hospitals have taken in dozens of patients from Italy and France. (Photo by Hendrik Schmidt/dpa via AP Photo/File)





An aerial photo shows Boeing 737 MAX airplanes parked on the tarmac at the Boeing Factory in Renton, Washington, U.S. March 21, 2019. (Photo by Lindsey Wasson/Reuters)





A British Airways Airbus A380 aircraft arrives over the top of residential houses to land at Heathrow Airport in west London, Britain, February 27, 2020. (Photo by Hannah McKay/Reuters)