A rail worker fixing a fog warning notice at South Woodford Railway Station in Essex. (Photo by H. F. Davis/Topical Press Agency/Getty Images). 20th October 1938

An F/A-18 Hornet assigned to Strike Fighter Squadron One Five One (VFA-151) emerges from a cloud created when it broke the sound barrier in the skies over the Pacific Ocean, July 7, 1999. (Photo by John Gay/US Navy)

U.S. Air Force pilots with the Thunderbirds perform the calypso pass maneuver in F-16 Fighting Falcon aircraft during a practice session prior to the Gunfighter Skies air show at Mountain Home Air Force Base, Idaho, September 19 and released September 24, 2014. (Photo by Tech. Sgt. Manuel J. Martinez/Reuters/US Air Force)

A United States Air Force (USAF) F-15 fighter jet travels at low altitude through the “Mach Loop” series of valleys near Dolgellau, north Wales on June 26, 2018. The Mach Loop valleys, situated between Dolgellau and Machynlleth, are regularly used by the military for operational low flying training which can take place as low as 76 metres from the nearest terrain. The USAF regularly use the loop to practice low-altitude flight, which confuses radar systems. (Photo by Oli Scarff/AFP Photo)

Film technicians at Pinewood Studios set up a miniature air crash sequence for the Jack Gold film “The Medusa Touch”, using scale models of a Boeing 747 and a skyscraper. (Photo by Alan F. Davis/Keystone/Getty Images). 9th August 1977

A unidentified woman protests at Broad Street for the pending arrival of Vice President Mike Pence at the Union League, in Philadelphia, Monday, July 23, 2018. Dozens of demonstrators dressed as characters from the novel-turned-TV series “The Handmaid's Tale” descended on downtown Philadelphia to protest Pence’s visit. (Photo by Jose F. Moreno/The Philadelphia Inquirer via AP Photo)

A F-16 fighter jet from The Thai Royal Air Force performs during a media demonstration at the Korat Royal Thai Air Force Base, Nakhon Ratchasima province, Thailand, November 24, 2015. Thailand's military held an air show with China on Tuesday ahead of joint manoeuvres in a sign of warming ties, but Thailand said it was not distancing itself from the United States which downgraded the military relationship following a 2014 coup. (Photo by Athit Perawongmetha/Reuters)