"On the Run" is the second (or third, if you count speak to me/breathe as 2 tracks) track from British progressive rock band Pink Floyd's 1973 album, The Dark Side of the Moon. It is an instrumental that deals with the pressures of travel (which Rick Wright said would often bring fear of death), and is a VCS3 synthesizer-led piece. When the band performed this song in concert, at the end of it, a model aeroplane would fly from one end of the arena to the other, appearing to crash in a brilliant explosion. The same effect was used in the A Momentary Lapse of Reason tours with a flying bed, and was an inspiration for the fictional band Disaster Area from The Hitchhiker's Guide to the Galaxy, whose stage act involves a spaceship crashing into the sun. During recording sessions, as well as in live appearances, this song was sometimes referred to as "the travel sequence."
This piece was created by feeding an 8 note sequence of semiquavers into the EMS VCS3 and speeding it up, with an added white noise generator creating the hi-hat sound. The band then added backwards guitar parts, created by dragging a microphone stand down the fretboard, reverse the tape, and panned left to right. There are also some other synthesizer parts, made to sound like some type of vehicle passing, giving a Doppler effect. The 8 note sequence (E, G, A, G on octave below Middle C, and D, middle C, D, E on Middle C octave) is played at a tempo of 166, and modulates upwards occasionally. Near the end, the explosion of the presumed aircraft is heard which gradually fades, segueing into the chiming clocks introduction of the following track "Time".
When the Dark Side of the Moon was performed in 1972 (before the album was released), it went under the title "The Travel Sequence" and was, instead of a complex electronic instrumental, a more simple guitar jam, without the use of synthesizers and other electronic instruments. A short clip of this is played on the DVD "Classic Albums: The Making of Dark Side of the Moon" and can also be heard on all performances of Pink Floyd playing the album live in that year.