WordNet
n. the path along which a freely moving object travels through the air
Wikipedia
A line of flight is a concept developed by Gilles Deleuze and used extensively in his work with Félix Guattari. Translator Brian Massumi notes that in French, "Fuite covers not only the act of fleeing or eluding but also flowing, leaking, and disappearing into the distance (the vanishing point in a painting is a point de fuite). It has no relation to flying."
In the first chapter of the second volume of their Capitalism and Schizophrenia project, A Thousand Plateaus (1980), the concept is used to define a " rhizome":
Multiplicities are defined by the outside: by the abstract line, the line of flight or deterritorialization according to which they change in nature and connect with other multiplicities. The plane of consistency (grid) is the outside of all multiplicities. The line of flight marks: the reality of a finite number of dimensions that the multiplicity effectively fills; the impossibility of a supplementary dimension, unless the multiplicity is transformed by the line of flight; the possibility and necessity of flattening all of the multiplicities on a single plane of consistency or exteriority, regardless of their number of dimensions.
In Manuel De Landa's book Intensive Science and Virtual Philosophy, the Line of Flight is described as an operator which transcends the real and ascends to the virtual. It is used as a synonym with Deleuze's terms "Dark Precursor" (from his Difference and Repetition (1968), " desiring machine" and "Quasi-Cause" (both from the first volume of Capitalism and Schizophrenia, Anti-Œdipus (1972)).
Usage examples of "line of flight".
The ship counterrotated with it, making sure that the protective canopy was always pointed precisely in the direction of the line of flight.
While Harty, Grady, and Roche, who was acting as loader, concentrated on setting up the Milan missile position, the balance of the tiny force, Sergeants Quinlan and Hannigan, infiltrated through the terrorists' perimeter defenses and set up a strike position less than a hundred meters from the two heavy-machine-gun positions and well to one side of the Milan's projected line of flight.
But the third and fourth entered through the starboard bulkhead and instead of exiting along their line of flight began to dart around the perimeter of the cabin, as if to fence the couple in.
If you start working out sums on my patrol I'll show you a new line of flight with the cube root of my foot when we get back on the ground!
The passage opening to the daylight and the valley beyond was too far and the black thing stood directly in her line of flight.
Milamber's actions held most other spectators riveted, and those in the rows above Mara's line of flight called down irritable comments as the passage of the Lady and her escort momentarily interrupted their view.
It didn't seem to be chasing anything, but her line of flight would lead her near to it.
The flyer whirled up into the sun of mid-morning and cut a straight course towards the rock teeth of the range, following the line of flight Dane and Tau had seen that shadow travel.
Suddenly it pointed to the right, more to the westward than their present line of flight.
And this was a crisis indeed, for twenty miles ahead, directly in his line of flight, something was rising out of the Star Gate.