Russian Mi-28N from the Berkuty (Golden Eagles) helicopter display team fly in formation during the “Aviadarts” military aviation competition at the Dubrovichi range near Ryazan, Russia, August 2, 2015. The aircraft started dipping down due to back propeller failure and crashed, killing one of two pilots, according to a Reuters photographer and official representatives of the competition. The aviation contest is part of the International Army Games, which are held in Russia from the 1st till the 15th of August with participants from 17 countries, according to organizers. (Photo by Maxim Shemetov/Reuters)

Afghan air force 2nd Lt. Niloofar Rhmani walks the flight line at Shindand Air Base, Afghanistan, prior to her graduation from undergraduate pilot training, on May 13, 2013. Rhmani made history on May 14, when she became the first female to successfully complete undergraduate pilot training and earn the status of pilot in more than 30 years. She will continue her service as she joins the Kabul Air Wing as a Cessna 208 pilot. (Photo by Senior Airman Scott Saldukas/USAF)

A woman shouts asking for help during an eviction in Rio de Janeiro, Brazil, Friday, April 11, 2014. Squatters in Rio de Janeiro are clashing with police after a Brazilian court ordered that 5,000 people be evicted from abandoned buildings of a telecommunications company. Officers have used tear gas and stun grenades to try to disperse the families. (Photo by Silvia Izquierdo/AP Photo)

Devotees offer prayer by rolling on the street during the final day of the month-long Swasthani festival of Bhaktapur, near Kathmandu, February 3, 2015. During the festival, devotees recite one chapter of a Hindu tale daily from the 31-chapter sacred Swasthani Brata Katha book, that is dedicated to God Madhavnarayan and Goddess Swasthani, alongside various other gods and goddesses and the miraculous feats performed by them. The devotees also go on pilgrimages to various temples, perform religious rituals, take a holy bath in the rivers and fast for a month, especially among women who believe fasting helps in their family's well-being or in getting them a good husband. (Photo by Navesh Chitrakar/Reuters)

A reveler takes part of the Light Festival parade in San Jose, Costa Rica on December 14, 2019. (Photo by Ezequiel Becerra/AFP Photo)

A couple shares a light moment in a Mass Transit Railway (MTR) subway train in Hong Kong, China on August 28, 2019. (Photo by Anushree Fadnavis/Reuters)

A Humboldt penguin swims in a pool during the annual stock take at ZSL London Zoo in London, Thursday, January 2, 2020. Caring for more than 500 different species, ZSL London Zoo's keepers face the challenging task of tallying up every animal large and small, every mammal, bird, reptile, fish and invertebrate at the Zoo. (Photo by Frank Augstein/AP Photo)

Former Vice President Joe Biden, 2020 Democratic presidential candidate, right, watches as his wife Jill Biden, center, blocks a protester from arriving on stage during an primary night rally in the Baldwin Hills neighborhood of Los Angeles, California, U.S., on Tuesday, March 3, 2020. The biggest day of the presidential primary calendar will define the nomination fight for Bernie Sanders and Biden and determine whether Michael Bloomberg and Elizabeth Warren have a rationale for carrying on their campaigns. (Photo by Patrick T. Fallon/Bloomberg via Getty Images)