Members of Germany's elite police unit, the Spezialeinsatzkommando, or SEK, demonstrate an abseil deployment from a helicopter during a media event on March 20, 2012 in Minden, Germany. The SEK is the special response team of Germany's state police force and typically deploys in high-risk situations, such as bank robberies, hostage takings and the arrest of armed and dangerous fugitives. (Photo by Thomas Starke/Getty Images)

In this October 15, 2014 file photo, Katsu Nakamura, sky division manager for Yamaha USA, moves the RMax unmanned helicopter into position before a demonstration of its aerial application capabilities at the University of California, Davis' Oakville Station test vineyard in Oakville, Calif. Researchers at UC Davis have been studying the effectiveness of the drone's ability for spraying pest control and nutritional materials on the test vineyard in California's Napa Valley. (Photo by Rich Pedroncelli/AP 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)

A member of the Philippine National Police stands guard as he detains people as part of the “Rid the Streets Of Drinkers and Youth” operation on a main road in Las Pinas city, metro Manila, Philippines June 1, 2016. (Photo by Romeo Ranoco/Reuters)

Mounted cop in action on Tremont Street in Boston, Massachusetts, 1920 – 1929 (approximate). (Photo by Leslie Jones)

A member of the Fuerza Civil (Civil Force) police unit takes part in a simulated crime situation during a media presentation to show the police model that the federal government wants for the rest of the country, at the police academy in Monterrey December 17, 2014. Fuerza Civil, a tactical team of the police unit trained by the army, was created by the Nuevo Leon government in 2011 to curb down corruption and infiltration by drug gangs in the police corps, local media reported. Promising a new law to stop the infiltration of local governments by organized crime, President Enrique Pena Nieto pledged to reform the penal system and send an proposal to Congress to unify multi-layered police forces in Mexico's 31 states. (Photo by Daniel Becerril/Reuters)

A British policewoman chasing after a group of naked street boys by the Serpentine in Hyde Park, London. (Photo by Reg Speller/Getty Images). 1926

Police academy graduates march during their graduation ceremony in Islamabad, Pakistan May 18, 2015. Out of the 408 graduating officers, 76 female officers were inducted into the Pakistan police force, according to the police force. (Photo by Caren Firouz/Reuters)