Mount Etna erupts in Sicily, Italy on February 21, 2021 sending plumes of ash and spewing lava into air. There was a major increase in volcanic activity that led to a paroxysmal event at the Southeast crater for the fourth time in the past six days. (Photo by Wead/Alamy Live News)

Men wear masks as they sit in the metro in Prague, Czech Republic, 17 March 2020. According to media reports, the Czech government decided to impose a two-week quarantine in the country on the evening of 15 March, and ban all international travel from 16 March 2020. Currently 383 cases of the coronavirus SARS-CoV-2, which causes the Covid-19 disease, have been officially confirmed in Czech Republic. (Photo by Martin Divisek/EPA/EFE)

A resident of the Goodwin House senior living community, looks on as the DC area motown band “The Tribe” plays a social distance concert in their parking lot in Arlington, Virginia, during the coronavirus pandemic on April 14, 2020. (Photo by Andrew Caballero-Reynolds/AFP Photo)

Number 10. BELL H-13 SIOUX was a two-bladed, single engine, light helicopter built by Bell Helicopter. Westland Aircraft manufactured the Sioux under license for the British military as the Sioux AH.1 and HT. In 1947, the United States Air Force ordered the improved Bell Model 47A. Most were designated YR-13 and three winterized versions were designated YR-13A. The United States Army first ordered Bell 47s in 1948 under the designation H-13. These would later receive the name Sioux. The Bell-built H-13 B is seen airborne in this April 29, 1951 photo. The helicopter is equipped with a 173 horsepower engine, cruises at 85 miles per hour, climbs 900 feet in a minute and has a service ceiling of 11,500 feet. (Photo by AP Photo)

Winton Elementary fifth graders Juliana Ragan, from left, Chloe Windsor and Paisley Ganske wait backstage for their turn to perform as the Andrew Sisters during the Pearl Harbor/Veterans assembly at the school on Monday, December 7, 2015, in Coeur d'Alene, Idaho. Dec. 7 is the 74th anniversary of the Japanese bombing of Pearl Harbor. (Photo by Kathy Plonka/The Spokesman-Review via AP Photo)

Police, bystanders and soldiers aid a fallen soldier at the War Memorial as police respond to an apparent terrorist attack on October 22, 2014 in Ottawa, Canada. A gunman is believed to have shot a soldier as he was standing guard at the National War Memorial in Ottawa. It is believed police then chased the man into the main parliament building at Parliament Hill, where more shots were fired. (Photo by Wayne Cuddington/Postmedia/Barcroft Media/ABACAPress)

A wounded protester is attended before being rushed to a vehicle following violence in Independence Square in Kiev February 20, 2014. Ukrainian protesters seized back Kiev's Independence Square in fresh clashes with riot police on Thursday that left several injured and possibly two demonstrators dead. (Photo by Konstantin Chernichkin/Reuters)