Just to add a bit of historical trivia to Nev's post if I may: The first commercial jet, a 36 seat Comet 1 built by De Havilland, flew for the first time in July 1949. Boac were the first to begin commercial jet operations when they began flying the Comets between London and Johannesburg in South Africa in May 1952. Unfortunately, The original Comet's square windows in the cabin were a serious design fault that caused the airframe to fail catastrophically in flight, and allowed Boeing to catch up, and in fact take over the lead in the race that began in the late 50s, and was in full swing by the early 60s, to supply the world with jet transport. As Nev said above, the commercial jets being built today are a hell of a lot more efficient than the four engined commercial jets (EG: B707, DC8, Convair 880 & 990) that were built in the late 50s and 60s, but none of todays jets are as fast. The Convair 880 and 990s as an example, which were built in the early 60s and have the same engines as the B58 Hustler and the F4 Phantom, are recognised as the fastest subsonic commercial aircraft ever built. They cruised at over Mk 0.9. But man alive, they were smokey sons of guns... One of Elvis Presley's personal jets, "Lisa Marie", which is parked across the street from "Gracelands" in Memphis, is a Convair 880. And John Travolta has a B707 (in old QANTAS colours even) which he parks in the back yard of his house just North of Ocala Florida.